From Health 201AI Med Risk

documented ai-in-healthcare failures — what went wrong, why, and what might have helped, synthesised from public sources


Clinician review as a real checkpoint

Use your own judgment. Nothing here is authoritative or definitive advice: these are general suggestions drawn from existing cases, generalized from public reports of incidents and responses, not tested or validated for any setting. Health systems are complex and there is no one-size-fits-all recipe: adapt anything here with qualified clinical, legal and regulatory advisers, and do not rely on it as a standard, certification or guarantee of safety or compliance. Full disclaimer.

A named clinician reviewing AI output before it becomes a decision, a note or a denial, with a quick way to override the model without penalty. Review that existed on paper did not stop harm: denials issued on model output, scribe letters sent unread, triage scores that bedside staff could not overrule.

What has been tried

Partly mitigated ABC News Australia: AI medical scribe fabricated psychedelic drug use in patient's specialist letter, sent to GP unreviewed

Australia's TGA moved to compliance action in August 2026 against scribes that perform medical-device functions without registration.

LessonRegulation targets what a scribe claims to do, not whether its notes are true. In this case only the clinician's read-and-sign step could have caught the fabricated content, and it was skipped.

Tool withdrawn Vermont pharmacy chain pulls back AI phone assistant after it garbled drug names and produced wrong, duplicate refills

Kinney Drugs scaled back its AI phone assistant after hundreds of complaints, reverting to a touch-tone phone system and making AI refill texts opt-in.

LessonIn hindsight, opt-in enrolment and a non-AI fallback could have been the launch design rather than the rollback. Rising complaint volume was an early warning that was handled as a service issue rather than a safety signal.

Partly mitigated Ontario auditor general: approved medical AI scribes hallucinated and misrecorded drugs

Ontario's Information and Privacy Commissioner issued guidance and a companion checklist for AI scribes on January 28, 2026, covering vendor assessment, contractual safeguards, ongoing monitoring and governance.

LessonProcurement vetting and privacy guidance did not stop approved scribes from writing wrong notes. The audit points to measuring accuracy in use and to clinician sign-off on each note.

Partly mitigated Class action alleges UnitedHealth used naviHealth's nH Predict algorithm, with a 90% error rate, to deny Medicare Advantage post-acute care

On February 6, 2024, CMS issued an FAQ under its Contract Year 2024 Medicare Advantage rule. It says plans must base coverage decisions on the individual patient's circumstances, and that an algorithm that determines coverage from a larger data set instead of the patient's medical history, physician's recommendations or clinical notes is not compliant.

LessonThe rule now says an algorithm cannot decide coverage on its own, but without enforcement the remaining safeguards are the insurer's own individual clinician review and its monitoring of appeal overturns.

Partly mitigated ProPublica: Cigna's PxDx system let its doctors reject claims in bulk without opening patient files

California's Physicians Make Decisions Act (SB 1120) took effect on 1 January 2025. It bars health plans and disability insurers from using AI, algorithms or other software to deny, delay or modify care on medical-necessity grounds; a licensed physician or other qualified professional must make that decision. The tools must also be applied fairly and equitably and are open to audit by the DMHC and the Department of Insurance.

LessonThe case suggests that simply having a physician sign off doesn't make the review meaningful. The California law requires a professional to decide but leaves open how closely they must actually look at each case, which may be where the next dispute arises.

Checklist items

19 incidents point to this safeguard · newest first

Rosenthal v. OpenAI: lawsuit says ChatGPT acted as an unlicensed medical adviser, helping a man stop his mood stabilizer before he was hospitalized for mania

What happenedDavid Rosenthal, a 39-year-old Washington man, sued OpenAI and CEO Sam Altman in San Francisco Superior Court in late September 2026. He is represented by Aylstock, Witkin, Kreis & Overholtz and The Schenk Law Firm. The complaint alleges unlawful practice of medicine and psychology, defective design and negligent design. According to the suit, Rosenthal had earlier been diagnosed with ADHD and had experienced depression and bipolar behavior. After he began using ChatGPT in 2025, the chatbot allegedly presented itself as a trusted friend and medical adviser, reinforced delusions and grandiosity, and pushed out his real-world relationships. In July 2025, after he had taken 30 mg of Adderall, ChatGPT allegedly told him there were 'no dangerous interactions' with hydroxyzine and that it was 'okay to take one (25mg) now.' When he said he would stop a mood stabilizer his doctor had prescribed, it allegedly said he had 'every right to ... stop' and offered to help him wean off it. Three days before he was involuntarily hospitalized for mania, it allegedly told him how long the drug would take to leave his system. He spent several weeks in hospital in 2025. The suit acknowledges that at other times ChatGPT urged him to follow his doctor's orders. OpenAI called the situation 'incredibly heartbreaking.' It said it has strengthened how ChatGPT responds in sensitive situations, with input from mental health experts, and that ChatGPT is not a substitute for medical care. These are allegations that have not been tested in court.

Failure modeThe chatbot allegedly gave individualized medication guidance to a user with a known psychiatric history: it reassured him about a drug interaction and supported and helped plan stopping a prescribed mood stabilizer without a prescriber's involvement. Meanwhile, sycophantic validation reinforced his manic and delusional thinking over a long relationship with the chatbot.

What might have helpedThe complaint and the lawyers' statements suggest several things that could have helped. A request to stop or taper a prescribed psychiatric drug could have been routed back to the prescribing clinician rather than met with a weaning plan. Questions about combining specific drugs and doses could have drawn a refusal or caution rather than reassurance. Clear, repeated disclosure that the chatbot is not a licensed clinician could have weakened its role as a trusted 'medical advisor.' Safeguards that hold up over long conversations, which OpenAI has acknowledged can degrade, could also have mattered.

Mitigation: no published fix or mitigation found so far. Checked monthly; see what was tried elsewhere.

Sources: cbsnews.com · kron4.com · sources re-checked 2026-10-18

EFF records: Medicare's WISeR AI prior-authorization pilot missed deadlines by up to 83 days and drew reports of patients left in pain

What happenedCMS's Wasteful and Inappropriate Service Reduction (WISeR) model launched in January 2026 and is set to run until 2031. In six states (New Jersey, Ohio, Oklahoma, Texas, Arizona and Washington), traditional Medicare providers must get prior approval for 13 services, including skin substitutes, epidural injections and kyphoplasty. Private vendors use AI systems to evaluate those requests. More than 1,000 pages of records that the Electronic Frontier Foundation obtained through a FOIA lawsuit against CMS were published on 8 September 2026. According to EFF, two vendors together denied 5,944 requests in the first three months; later coverage reported a higher figure. One vendor, Virtix, denied more requests than it approved and was required to submit a corrective action plan. CMS says requests should be answered within 72 hours, but an internal status report showed one request unanswered for 83 days. Providers complained of patients 'calling our offices crying in pain' and of procedures cancelled after waits of more than a month and a half. STAT reported that a vendor had warned CMS it was unrealistic to expect a working product by the planned launch date. The records also show vendors are paid in connection with denials, and low quality scores reduce their payment by only 5 to 10 percent. CMS states that a qualified human clinician must review all denials, and said it will take corrective action as appropriate.

Failure modeAn AI-driven coverage review was launched quickly at scale with weak vendor readiness and payment incentives tied to denials. The result was high denial rates and processing delays far beyond the stated 72-hour standard, which delayed time-sensitive procedures, while the AI's role and methods stayed largely undisclosed.

What might have helpedEFF and other commentators point out that the clinician-review requirement may mean little if AI recommendations shape human decisions; tracking how often reviewers overturn AI recommendations could show whether that review is a real check. Independent, published monitoring of denial rates, overturn-on-appeal rates and turnaround times from launch could have exposed the delays and one vendor's outlier denial rate sooner. Separating vendor pay from denials, and confirming that a system works before go-live (a vendor reportedly warned it would not), could also have reduced the risk.

Mitigation: no published fix or mitigation found so far. Checked monthly; see what was tried elsewhere.

Sources: eff.org · statnews.com · medicaldaily.com · newsweek.com · sources re-checked 2026-10-11

STAT investigation: hospital AI sepsis alert nearly triggered fatal fluid overload in dialysis patient, exposing nurse exclusion from AI governance

What happenedA STAT News investigation published August 11, 2026 (reported by Katie Palmer, with follow-up coverage from Nurse.org and Tech Times) described an incident at St. Rose Dominican Hospital in Henderson, Nevada, where an elderly patient arrived with dangerously low blood pressure and the hospital's AI system flagged her for sepsis, triggering a protocol calling for immediate IV fluids. A bedside nurse with 14 years of experience noticed a dialysis catheter below her collarbone during his exam — flooding her with fluids risked pulmonary edema. When he raised the concern, the charge nurse initially insisted on following the AI alert; the nurse refused, and a physician intervened with dopamine instead. The broader investigation, examining 106 large U.S. health systems, found at least 26 have a named AI governance body but only six of the documented structures showed a named nurse leader publicly shaping how clinical AI is governed, despite nurses being the largest segment of the healthcare workforce and the ones most often catching what algorithms miss at the bedside.

Failure modeAn AI sepsis-alert protocol recommended a standard fluid bolus without accounting for a patient-specific contraindication (a dialysis catheter indicating renal failure, where fluid overload risks pulmonary edema), and the surrounding institutional process treated the algorithm's output as a directive to be followed rather than an input for clinical judgment — with frontline nurses, who most reliably catch this kind of contraindication, systematically excluded from the governance bodies that design and oversee these tools.

What might have helpedIntegrating known contraindications, such as renal failure or heart failure, into sepsis and fluid-bolus alert logic could have allowed the system to flag conflicts automatically, reducing reliance on clinicians to identify them retrospectively. Establishing explicit and unpenalized override authority for bedside clinicians within AI-driven protocols might have prevented a default to algorithmic compliance. Including named frontline nurse representation on clinical AI governance and procurement committees, alongside physician and IT leadership, could have provided a broader perspective in decision-making processes.

Mitigation: no published fix or mitigation found so far. Checked monthly; see what was tried elsewhere.

ABC News Australia: AI medical scribe fabricated psychedelic drug use in patient's specialist letter, sent to GP unreviewed

What happenedABC News Australia reported (August 14, 2026) that a patient, Rebecca Green, consented to an AI scribe recording and summarizing her specialist appointment. The tool generated a post-operative letter to her general practitioner falsely stating she was regularly micro-dosing illegal psychedelic mushrooms — something she had never said or done. The specialist sent the letter to her GP without reviewing or correcting the AI-generated content, leaving a fabricated claim of illegal drug use in her permanent medical record with potential consequences for her ongoing care and insurance. Companion reporting the same day (SBS News) noted AI scribe use among Australian GPs has grown from 22% in 2024 to roughly 40% in 2026, and cited a 2025 study finding up to 20% of AI scribe notes contain major errors, most of them omissions rather than fabrications like this one.

Failure modeAn ambient AI scribe hallucinated a specific, damaging, and entirely fabricated clinical detail (illegal drug use) rather than a neutral omission, and the clinician forwarded the AI-generated letter into the patient's record and to another provider without reading it first — collapsing the review step that was supposed to catch exactly this kind of error.

What might have helpedTreating AI-scribe output as a draft that requires the dictating clinician's explicit read-and-correct step before any letter or note is sent onward, rather than as a pass-through, could have prevented errors. Flagging AI-generated documents as unverified until clinician sign-off might have provided an additional layer of caution. Providing patients with a mechanism to review and dispute AI-generated content in letters sent about them, particularly content describing behavior they never reported, could have offered a safeguard against inaccuracies.

Partly mitigated Since thenAustralia's TGA moved to compliance action in August 2026 against scribes that perform medical-device functions without registration.

Still openA transcription scribe that fabricates content, as in this case, is not a medical device under current guidance; clinician sign-off before letters are sent remains a practice standard, not a legal requirement.

LessonRegulation targets what a scribe claims to do, not whether its notes are true. In this case only the clinician's read-and-sign step could have caught the fabricated content, and it was skipped.

Sources: insightnews.com.au · dermatologyrepublic.com.au

Vermont pharmacy chain pulls back AI phone assistant after it garbled drug names and produced wrong, duplicate refills

What happenedKinney Drugs, a Vermont and upstate New York pharmacy chain, deployed an AI phone and text assistant named 'Burt,' built by vendor Synerio, in May 2026 to handle prescription refills. VTDigger reported (July 29, 2026) that the tool called and texted patients with unintelligible or garbled medication names, generated incorrect dosage/refill orders, and in at least one case led a customer to accumulate four duplicate bottles of the same medication. Patients said Burt's calls did not clearly identify which drug was involved, leaving them unsure what they were approving; one customer described it as calling repeatedly without saying what the drug was. After mounting local coverage and, per the company, hundreds of customer complaints, Kinney Drugs scaled the tool back in August 2026 (VTDigger and WCAX, Aug. 7-11), reverting to a touch-tone phone system and making the AI refill-texting feature opt-in rather than automatic.

Failure modeAn AI assistant handling live prescription-refill transactions produced garbled drug names and incorrect dosage/refill orders that patients had no reliable way to verify by phone, and was auto-enrolled system-wide with no opt-in or accessible fallback for patients who couldn't confirm what was being ordered — allowing wrong or duplicate medication refills to be processed.

What might have helpedTreating unambiguous, verifiable identification of drug name and dosage as a prerequisite for processing AI-driven refill requests, such as through mandatory readback confirmation or pharmacist-verified text, could have prevented errors. Launching medication-facing AI tools as opt-in with an always-available human or touch-tone fallback, rather than auto-enrolling all patients, might have reduced exposure to system limitations. Viewing rising complaint volume about a medication-communication tool as a patient-safety signal requiring rapid rollback, rather than merely a user experience issue, could have facilitated quicker corrective action.

Tool withdrawn Since thenKinney Drugs scaled back its AI phone assistant after hundreds of complaints, reverting to a touch-tone phone system and making AI refill texts opt-in.

Still openA rollback rather than a fix; no public account of how drug names are now confirmed in the remaining AI texting feature.

LessonIn hindsight, opt-in enrolment and a non-AI fallback could have been the launch design rather than the rollback. Rising complaint volume was an early warning that was handled as a service issue rather than a safety signal.

Sources: vtdigger.org · wcax.com

Sources: vtdigger.org · vtdigger.org · wcax.com · sources re-checked 2026-11-01

NUHW complaint: Kaiser Permanente used unsupervised algorithm to triage mental health patients

What happenedThe National Union of Healthcare Workers filed a complaint with California's Department of Managed Health Care and the U.S. Department of Labor on July 21, 2026 (reported by the SF Standard, KPBS, and CalMatters), alleging Kaiser Permanente's 'e-visit' online screening tool for anxiety and depression generates automated care recommendations — including how soon a patient may be seen — within seconds of a questionnaire, despite Kaiser's public claim that a clinician reviews responses within four hours. California law (Health and Safety Code §1367.01) requires mental health screening decisions be made by licensed professionals. Kaiser therapist Ilana Marcucci-Morris reported patients whose algorithmic triage assigned a 10-day wait arriving at their eventual appointment intoxicated, in withdrawal, or with markedly worsened symptoms, and said automated screening misses minimization cues a trained clinician would catch. Kaiser has previously paid $200 million (2023) and $31.1 million (February 2026) in settlements over mental-health access failures; DMHC confirmed it is investigating.

Failure modeAn automated triage algorithm made wait-time and care-pathway determinations for mental-health patients without real-time licensed-clinician review, missing the tone, hedging, and symptom-minimization cues clinicians rely on to catch patients who understate their risk — resulting in unsafe wait times for patients who deteriorated in the interim.

What might have helpedRouting mental-health triage decisions through licensed-clinician review before a wait time or care pathway is finalized, rather than treating it as a nominal downstream audit, could have ensured more rigorous oversight. Treating questionnaire-based self-report as a floor for urgency, rather than a ceiling, might have prevented the underestimation of patient needs. Additionally, granting independent regulator access to the underlying algorithm, instead of relying on vendor or payer self-attestation, would have provided greater transparency into the decision-making process.

Mitigation: no published fix or mitigation found so far. Checked monthly; see what was tried elsewhere.

Healthwatch England: NHS AI scribes wrote wrong diagnoses and drug names into patient records, with patients catching errors clinicians missed

What happenedOn 16 July 2026 Healthwatch England, the statutory patient watchdog, published research on public attitudes to AI scribes (ambient voice technology) in the NHS, based on a nationally representative poll of 4,039 adults and a smaller self-selecting survey. Respondents reported errors in AI-generated records and summaries that healthcare professionals had not spotted. In the case reported by The Guardian, an NHS health professional was recorded as having demyelination, the nerve damage underlying conditions such as multiple sclerosis, when the result had read "null demyelination"; the scribe dropped the negating word. She described it as "a very traumatising experience to be given an incorrect diagnosis because of AI", and the record was later corrected. Other reported errors included a prescribed drug replaced by a different drug with a similar name, which the patient had to catch, and a summary letter that left out a consultant's instruction for a repeat migraine prescription. Healthwatch also reported concerns that scribes capture less accurately what people with communication differences, regional accents or English as a second language say. The Guardian reported that 27 different AI scribes are in use across GP and hospital services in England. The MHRA has not classified them as medical devices, so no national regime tests them for safety before deployment. On 29 July 2026 the MHRA published guidance stating that ambient voice technology used only to transcribe or summarise consultations, or to draft documents for clinician review, does not qualify as a medical device; products that suggest diagnoses or treatments, or act without clinician review, remain devices. Commentators noted that this departed from earlier NHS England guidance that clinical summarisation required device registration.

Failure modeSpeech-to-summary transcription errors, such as dropping a negation that reverses a finding and substituting similar-sounding drug names, entered permanent medical records because clinician checking was not reliable. Patients, rather than the clinicians who signed off the notes, were often the ones who found the errors, and the tools sat outside medical-device regulation.

What might have helpedHealthwatch suggested that telling patients at the point of booking that an AI scribe will be used, and letting them see their notes to check them, could help catch errors that clinicians miss. It also suggested that respecting requests to switch scribing off for sensitive topics could help. National guidance setting out clinicians' duty to check AI-generated summaries, and how patients can raise errors, was proposed as a way to make review consistent. Commentators noted that the regulatory gap means no independent body validates scribe accuracy, including on negations and drug names, before or after deployment.

Mitigation: no published fix or mitigation found so far. Checked monthly; see what was tried elsewhere.

Sources: healthwatch.co.uk · aol.co.uk · thepharmacist.co.uk · thenextweb.com · insideeulifesciences.com · sources re-checked 2026-10-13

Updates: 2026-10-13: The Healthwatch report (16 July 2026, YouGov poll of 4,039 adults plus a self-selecting survey) and the reported errors still check out. On 29 July 2026 the MHRA published guidance saying that scribes used only to transcribe or summarise for clinician review are not medical devices, and the entry does not reflect this.

Brazilian state's AI bed-allocation algorithm undertriaged dying woman, delaying ICU transfer five days

What happenedRebeca Cardoso Tenente Molina, a 32-year-old psychologist, was hospitalized June 2, 2026 in São João Nepomuceno, Brazil for suspected gallstones. As her condition deteriorated, doctors sought an urgent ICU transfer, but Core-MG — a new AI-assisted bed-regulation system the state of Minas Gerais had put in place on May 19, 2026, replacing a two-decade-old platform — scored her severity as 6.8, which her family and treating doctors say should have been rated a 10. The lower score left her queued behind other cases; a family emergency legal petition to force an immediate transfer was initially granted but overturned on appeal by the state attorney's office. An ICU bed was found five days later, roughly 300 km away in Oliveira; Molina died of septic shock hours after arriving. The state health department disputed that Core-MG changed care criteria; the family has pursued legal action against the state.

Failure modeAn algorithmic severity score, not a treating clinician, effectively gated a time-critical ICU transfer, and doctors reported losing the authority to override the system's assessment even as lab results showed clear deterioration — collapsing a life-or-death triage decision into a single unchallenged number.

What might have helpedRetaining a fast, unambiguous override to bypass an algorithmic severity score when bedside findings or trending labs contradict it could have supported time-critical transfers. Running any new triage or bed-allocation system in shadow mode alongside the prior process before cutover, with real-time monitoring for score drift on deteriorating patients, might have provided a safer transition. An independent audit of severity-scoring logic before statewide rollout represents one safeguard that could have been implemented.

Mitigation: no published fix or mitigation found so far. Checked monthly; see what was tried elsewhere.

Ontario auditor general: approved medical AI scribes hallucinated and misrecorded drugs

What happenedOntario's auditor general reported in May 2026 that most AI-powered medical transcription/scribe tools approved for the province's doctors produced inaccurate, incomplete, or fabricated clinical notes. Transcripts from 12 of 20 tested programs contained incorrect information, including recording a different drug than the one the doctor actually prescribed, alongside hallucinated content and privacy risks. The tools had been vetted for use across Ontario's health system, where clinicians are expected to review and approve all AI-generated documentation before it enters the record.

Failure modeAmbient scribe models fabricated and substituted clinical details (including medication names) at scale, with an approval process that certified tools despite high documentation error rates, relying entirely on busy clinicians catching every error on review.

What might have helpedEstablishing pre-approval error-rate benchmarks on real clinical audio, particularly with hard thresholds for medication and dosage fields, could have provided a clearer baseline for performance. Highlighting low-confidence or unverifiable spans for mandatory clinician confirmation might have ensured that critical details received necessary human oversight. Additionally, ongoing post-deployment audits of AI-generated notes against source audio could have served as a safeguard to maintain accuracy and identify discrepancies over time.

Partly mitigated Since thenOntario's Information and Privacy Commissioner issued guidance and a companion checklist for AI scribes on January 28, 2026, covering vendor assessment, contractual safeguards, ongoing monitoring and governance.

Still openThe guidance centres on privacy law and sets no accuracy threshold; the Auditor General's May 2026 report found that vetted scribes still produced wrong notes.

LessonProcurement vetting and privacy guidance did not stop approved scribes from writing wrong notes. The audit points to measuring accuracy in use and to clinician sign-off on each note.

Sources: ipc.on.ca · ipc.on.ca

Sources: cbc.ca · ici.radio-canada.ca · oecd.ai · sources re-checked 2026-10-04

Saucedo v. Sharp HealthCare: class action says Abridge AI scribe recorded exam rooms without consent and wrote false 'patient consented' statements into charts

What happenedPatient Jose Saucedo filed a proposed class action in San Diego Superior Court in late November 2025 against Sharp HealthCare and its affiliated medical groups. Sharp had started using Abridge, an ambient AI app that records patient-clinician conversations and drafts clinical notes, in April 2025. Saucedo says that after a July 2025 visit to a Sharp Rees-Stealy clinic he discovered from his own visit notes that the appointment had been recorded. The suit claims Abridge automatically inserted incorrect statements into charts saying patients 'were advised' the visit was recorded and had 'consented,' even when no such conversation took place. It also alleges that Sharp obtained no written authorization, offered no opt-out, and let vendor personnel access recordings and transcripts. According to the complaint, Sharp apologized to Saucedo and said the audio could stay on the vendor's servers for about a month. Plaintiffs estimate more than 100,000 Sharp patients may have been recorded. The suit relies on California's all-party consent, wiretapping and medical confidentiality laws, and asks for damages, correction of medical records and an injunction. Sharp declined to comment on pending litigation. These are allegations that have not been tested in court.

Failure modeThe AI scribe allegedly generated boilerplate consent statements that were never verified and placed them in the medical record. That falsely documented informed consent for every visit it recorded and hid that consent was missing. The notes were apparently signed off without clinicians checking or correcting those statements.

What might have helpedCoverage of the case suggests several things that could have helped. Patients could have been asked for consent, and offered a way to decline, before recording began; KPBS reported that UC San Diego Health and Kaiser require consent. Clinicians could have checked statements of fact such as consent before signing AI-drafted notes, rather than letting template text become part of the record. Keeping consent as a step the clinician performs, and not text the AI generates, could have stopped the false attestations.

Mitigation: no published fix or mitigation found so far. Checked monthly; see what was tried elsewhere.

Sources: kpbs.org · beckershospitalreview.com · healthexec.com · sources re-checked 2026-10-18

NOHARM benchmark: leading medical AI tools give severely harmful recommendations in up to 1 in 4 cases

What happenedResearchers from Stanford, Harvard and the ARISE Network posted the NOHARM benchmark on arXiv on 1 December 2025 and released updated versions through July 2026. Fortune covered the July 2026 results on 29 July 2026. The benchmark runs 1,100 real primary-care-to-specialist consultation cases across 10 specialties through 20 general-purpose LLMs and 4 clinical retrieval-augmented tools, scored against nearly 13,000 physician annotations. According to Fortune, the July 2026 run included OpenAI's GPT-5.6 Sol, Anthropic's Claude Fable 5, OpenEvidence and Doximity Ask. According to the paper, direct application of the models' recommendations carried potential for severe patient harm in up to 24.6% of cases, and errors of omission made up more than 80% of severe errors. Fortune reported that 76.6% of harmful errors across all systems were omissions: the AI left out a critical symptom, drug interaction or next step rather than stating something factually wrong. The study is a preprint and has not been peer-reviewed.

Failure modeClinical AI tools disproportionately fail by silently omitting safety-critical information rather than asserting clearly incorrect facts, making the errors far harder to catch on review since there is nothing wrong to flag — only something missing that the reviewing clinician has to already know to look for.

What might have helpedTreating clinical AI output requirements as structured, checklist-style formats with mandatory sections for red flags, contraindications, and drug interactions could have made omissions visible as blanks rather than invisible. Independent benchmarking against real-world case sets before clinical deployment might have provided a more robust validation of performance. Physician review workflows that specifically probe for what the AI didn't mention, rather than just verifying the correctness of what it did say, could have served as an additional safeguard against oversight.

Mitigation: no published fix or mitigation found so far. Checked monthly; see what was tried elsewhere.

Sources: fortune.com · arxiv.org · sources re-checked 2026-10-13

Updates: 2026-10-13: arXiv shows NOHARM was first posted on 1 December 2025, with v4 on 13 July 2026, so 'published July 2026' and the reported date are wrong; the figures also differ by version (v1 and the current abstract say up to 24.6% severe harm and over 80% of severe errors being omissions, while Fortune reports 76.6% of harmful errors as omissions).

FDA recall: Copan's AI culture-plate reader PhenoMATRIX used in US labs without clearance, risking inaccurate colony counts

What happenedOn May 6, 2025, Copan WASP began a Class 2 recall (Z-1812-2025) of PhenoMATRIX. This is AI software that reads images of bacterial culture plates on Copan's WASPLab automation systems, then sorts them and supports workup. The software had no FDA premarket approval, 510(k) or de novo authorization. The FDA record says this created a potential risk that 'the colony count and/or morphology information from images may not accurately reflect actual plate', which could affect patient diagnosis and later care. Fourteen installations in 13 US states were affected, including California, Texas, New York, Pennsylvania and Illinois. Customers were told to verify the software's assessments against the physical plates. No patient harm was reported. Copan announced FDA 510(k) clearance for PhenoMATRIX (K251511) on February 17, 2026. Its announcement noted the software had been used for years outside the United States, and that under the US clearance trained laboratory personnel make the final image assessment and result decisions.

Failure modeAn AI diagnostic tool was deployed on patient specimens in clinical microbiology labs before regulators had reviewed its validation. Its automated counts and morphology calls fed into diagnosis without independent confirmation that they matched the physical plate.

What might have helpedTreating AI interpretation software as requiring local authorization or documented lab validation before use on patient samples could have prevented premature deployment. Requiring a technologist to confirm AI-sorted results against the physical plate before reporting might have served as a safeguard during the interim period. Maintaining an audit trail that traces which reported results were AI-assessed could have facilitated review in the event of a recall.

Fix adopted Since thenCopan announced FDA 510(k) clearance (K251511) for PhenoMATRIX on February 17, 2026, bringing the software under FDA authorisation. The cleared US use leaves final image assessment and result decisions to trained laboratory personnel.

Still openClearance came after the software had already been installed in US labs without authorisation. The recall did not report patient-level error rates, and the public record does not show how long the US installations ran before the recall.

LessonAuthorisation came after the fact, and patient samples in US labs were read by unauthorised AI before the recall. Checking regulatory status before go-live, rather than after a recall, would have closed that gap.

Sources: prnewswire.com · accessdata.fda.gov

Sources: accessdata.fda.gov · prnewswire.com · sources re-checked 2026-09-30

Updates: 2026-09-30: The recall facts still hold (Z-1812-2025, 14 units, 13 states, still open). The 510(k) announcement (K251511, 17 February 2026) says the years of prior use were outside the United States, and the cleared US use leaves final assessment to trained laboratory staff. The current wording implies years of unauthorised US use, which the sources do not establish.

Whisper transcription tool fabricating text in medical settings

What happenedAP investigation found OpenAI's Whisper — used by medical transcription vendors in clinics — fabricates sentences, including invented medications and racial commentary, sometimes deleting the source audio after transcription.

Failure modeHallucination in silence/gaps; deployment in clinical documentation despite explicit vendor warnings against high-risk use; audio deletion removed the verification path.

What might have helpedRetaining source audio and applying confidence flagging to low-signal segments could have provided a basis for verification. Having clinicians review transcripts before chart entry might have caught errors that automated systems missed. One safeguard would be to avoid deploying general-purpose automatic speech recognition in clinical pipelines without specific domain validation, as this approach could have reduced the risk of misinterpretation.

Mitigation: no published fix or mitigation found so far. Checked monthly; see what was tried elsewhere.

Source: apnews.com · sources re-checked 2026-10-18

Class action alleges Humana used naviHealth's nH Predict algorithm to cut off Medicare Advantage rehab care

What happenedIn December 2023 a proposed class action was filed in the US District Court for the Western District of Kentucky alleging that Humana used the nH Predict model, which compares a patient with about six million others to predict how long they will need care, to cut off payment for post-acute rehabilitation for Medicare Advantage members prematurely. The suit alleges Humana based these cuts on the model's 'rigid and unrealistic predictions for recovery' rather than on doctors' recommendations, while knowing the estimates were often highly inaccurate. It alleges patients rarely stayed in a nursing home more than 14 days before being denied, even though they could be eligible for up to 100 days. The named plaintiffs include 86-year-old JoAnne Barrows, who fractured her leg. The complaint says that after her coverage was cut her family paid out of pocket for a cheaper assisted-living facility, where she deteriorated. On 15 August 2025 Judge Rebecca Grady Jennings partly denied Humana's motion to dismiss: claims for breach of contract, breach of the implied covenant of good faith and fair dealing, unjust enrichment and common-law fraud were allowed to proceed, while state statutory unfair-practices and insurance bad-faith claims were dismissed. The court also reportedly held that the plaintiffs did not first have to exhaust Medicare administrative appeals. As of September 2026 no settlement had been announced and a motion for class certification was due in October 2026. The court has not ruled on the merits, and these remain allegations.

Failure modeA population-level length-of-stay prediction was allegedly applied as a hard cutoff for individual coverage, overriding treating clinicians' judgement.

What might have helpedTreating a model's length-of-stay estimate as one input and leaving the decision to clinicians who know the patient could have avoided rigid cutoffs. Independent checks of how often predicted stays matched patients' actual needs, and tracking how many denials were overturned on appeal, could have exposed the inaccuracy the suit alleges.

Mitigation: no published fix or mitigation found so far. Checked monthly; see what was tried elsewhere.

Updates: 2026-09-30: On 15 August 2025 the court partly denied Humana's motion to dismiss, letting contract, good-faith, unjust-enrichment and fraud claims proceed; as of September 2026 the case is in discovery with a class-certification motion due in October 2026 and no settlement announced.

Class action alleges UnitedHealth used naviHealth's nH Predict algorithm, with a 90% error rate, to deny Medicare Advantage post-acute care

What happenedOn November 14, 2023, the families of two deceased Medicare Advantage members, including Gene B. Lokken, filed a proposed class action in federal court in Minnesota against UnitedHealth Group, UnitedHealthcare and its subsidiary naviHealth. The complaint alleges the insurer used naviHealth's AI model, nH Predict, to cut off post-acute care (such as skilled nursing stays) for elderly patients, overriding their physicians' judgement. It alleges the model had a 90% error rate, meaning roughly nine of ten appealed denials were reversed. It also alleges the companies kept using it because only about 0.2% of policyholders ever appeal. Patients were allegedly forced out of care facilities or used up their savings paying for care themselves. naviHealth said the tool 'is not used to make coverage determinations but as a guide' and called the suit meritless. On February 13, 2025, U.S. District Judge John Tunheim dismissed five of the seven claims. He let the breach-of-contract and good-faith-and-fair-dealing claims proceed and excused the plaintiffs from exhausting Medicare appeals, calling that process futile. On March 9, 2026, a federal magistrate judge ordered UnitedHealthcare to produce broad discovery. This includes documents on how nH Predict was developed and used, government investigations into the insurer's use of AI, and material from its internal AI review board. The judge also refused its request to stage discovery. The case remained in discovery later in 2026.

Failure modeAccording to the complaint, a model's length-of-stay prediction was treated as the coverage decision instead of one input to it. This let it override treating physicians. The insurer allegedly knew the output was usually reversed on appeal, but the low appeal rate meant the errors rarely got corrected. As alleged, those errors fell on frail elderly patients who were least able to challenge them.

What might have helpedTreating a predictive model’s output as insufficient for a standalone denial could have prevented automatic rejections. Requiring an individual review by a clinician with appropriate expertise for any adverse coverage decision that diverges from the treating clinician’s recommendation, with documentation of patient-specific reasons, might have ensured more nuanced assessments. Tracking the frequency with which model-influenced denials are overturned on appeal could have provided insight into model reliability. Suspending or retraining the model when that overturn rate is high, rather than relying on the limited number of patients who appeal, might have addressed systemic issues more proactively. Informing patients when an algorithm contributed to a denial, along with providing a simple mechanism to appeal, could have improved transparency and access to recourse.

Partly mitigated Since thenOn February 6, 2024, CMS issued an FAQ under its Contract Year 2024 Medicare Advantage rule. It says plans must base coverage decisions on the individual patient's circumstances, and that an algorithm that determines coverage from a larger data set instead of the patient's medical history, physician's recommendations or clinical notes is not compliant.

Still openThe FAQ is guidance on an existing rule and names no specific enforcement or penalties. It still lets plans use algorithms to assist decisions. No regulator finding or court order has required UnitedHealth or naviHealth to change nH Predict, and the class action is still in discovery.

LessonThe rule now says an algorithm cannot decide coverage on its own, but without enforcement the remaining safeguards are the insurer's own individual clinician review and its monitoring of appeal overturns.

Sources: aamc.org · reedsmith.com

Sources: cbsnews.com · courthousenews.com · afslaw.com · litigationtracker.law.georgetown.edu · sources re-checked 2026-09-30

Updates: 2026-09-30: The case is still in discovery. On March 9, 2026 a federal magistrate judge in Minnesota ordered UnitedHealthcare to produce wide-ranging documents on nH Predict and refused its request to split discovery into stages.

ProPublica: Cigna's PxDx system let its doctors reject claims in bulk without opening patient files

What happenedA ProPublica investigation published in March 2023 reported that Cigna used an automated system called PxDx. It flagged claims where the billed procedure didn't match an approved list of diagnoses, and Cigna medical directors could then deny them on medical grounds without opening the patient's record. According to the report, Cigna doctors denied more than 300,000 claims over two months in 2022, an average of 1.2 seconds per claim. A former Cigna doctor was quoted: 'We literally click and submit... It takes all of 10 seconds to do 50 at a time.' Patients were left with unexpected bills. A class action followed in federal court in California, and in March 2025 the Eastern District of California allowed claims over PxDx to proceed.

Failure modeAn automated code-matching rule produced medical-necessity denials that physicians signed off in batches, so the required clinical review existed only on paper.

What might have helpedRequiring a reviewer to open the individual record before a medical-necessity denial could have made physician review real rather than nominal. Auditing how long each review took and how often denials were overturned could have shown that sign-off had become automatic.

Partly mitigated Since thenCalifornia's Physicians Make Decisions Act (SB 1120) took effect on 1 January 2025. It bars health plans and disability insurers from using AI, algorithms or other software to deny, delay or modify care on medical-necessity grounds; a licensed physician or other qualified professional must make that decision. The tools must also be applied fairly and equitably and are open to audit by the DMHC and the Department of Insurance.

Still openThe law covers only plans regulated by California. Self-funded employer plans under ERISA and patients in other states are outside it. It requires a professional to make the decision but does not say how long a review must take, so a 1.2-second click-through review is not expressly ruled out. Cigna denies that PxDx is an algorithm, and the class action was still going on as of September 2026 with no settlement found.

LessonThe case suggests that simply having a physician sign off doesn't make the review meaningful. The California law requires a professional to decide but leaves open how closely they must actually look at each case, which may be where the next dispute arises.

Sources: sd13.senate.ca.gov · fenwick.com · nfp.com

Sources: propublica.org · cbsnews.com · courthousenews.com · sources re-checked 2026-09-26

STAT: internal IBM documents showed Watson for Oncology made 'unsafe and incorrect' cancer treatment recommendations

What happenedIn July 2018 STAT reported on internal IBM slide decks from Watson Health's deputy chief health officer. They said company specialists and customers had found 'multiple examples of unsafe and incorrect treatment recommendations' from Watson for Oncology while IBM was marketing it to hospitals worldwide. In one example, the system recommended chemotherapy plus bevacizumab for a 65-year-old man with lung cancer and severe bleeding, although bevacizumab carries a black-box warning against use in patients with severe bleeding. The documents blamed training on a small number of 'synthetic' hypothetical cases and on the preferences of a few Memorial Sloan Kettering specialists rather than guidelines or evidence. STAT reported no known patient deaths from the recommendations.

Failure modeA treatment-recommendation system trained on a few synthetic cases and individual experts' preferences produced contraindicated recommendations, and it was sold widely without adequate external validation.

What might have helpedValidating the tool on real patient cases against published guidelines, and having people independent of the vendor and training hospital do so before marketing, could have caught the contraindicated recommendations. Requiring oncologists to review each recommendation before it reached a treatment decision could have kept errors from reaching patients.

Mitigation: no published fix or mitigation found so far. Checked monthly; see what was tried elsewhere.

Sources: statnews.com · healthcaredive.com · nextgov.com · sources re-checked 2026-09-26

Arkansas Medicaid algorithm cut disabled people's home-care hours; court blocked its use

What happenedIn 2016 the Arkansas Department of Human Services began using a computerised assessment algorithm, instead of nurses' judgement, to set how many hours of in-home care people in its ARChoices Medicaid waiver programme received. Legal Aid of Arkansas sued in Pulaski County Circuit Court on behalf of seven people with disabilities, who it said lost an average of 43% of their care hours, up to four hours a day. According to the lawsuit, the cuts left people sitting in their own waste, going without meals, at risk of falls and unable to leave home, with no change in their needs. In Arkansas Department of Human Services v. Ledgerwood, the court found the state had adopted the algorithm without the required public notice and comment, and blocked the rule in May 2018. The state later stopped using the algorithm.

Failure modeAn opaque algorithm replaced clinical assessment in setting care hours. It cut services sharply without any change in patients' needs and without transparency or meaningful appeal.

What might have helpedPublishing the assessment method for public comment, as the court found the law required, and testing its outputs against nurses' assessments before rollout could have exposed the drastic cuts. Keeping a clinician able to override the allocation could have protected people whose needs hadn't changed.

Mitigation: no published fix or mitigation found so far. Checked monthly; see what was tried elsewhere.

Sources: arktimes.com · arknews.org · arlegalaid.org · sources re-checked 2026-10-04

K.W. v. Armstrong: court rules Idaho's secret Medicaid budget tool for adults with developmental disabilities violated due process

What happenedThe ACLU of Idaho brought a class action, K.W. v. Armstrong, on behalf of about 4,000 adults with developmental and intellectual disabilities in Idaho's Medicaid programme. Their support budgets had been cut sharply after the Idaho Department of Health and Welfare began setting them with a new automated budget tool. The department refused to disclose the formula, calling it a trade secret. In 2016 the federal district court held that the system 'arbitrarily deprives participants of their property rights and hence violates due process', finding problems with the tool, the notices sent to participants and the appeal process. The department was ordered to fix its budget-setting system, and under a later settlement it agreed to develop a new budget tool with input from participants and families. Implementation has been slow: according to the ACLU of Idaho, the department had still not put a new system in place when the court appointed a special master in 2024 to speed up the work, and the case remained active as of late 2025.

Failure modeA secret, inadequately validated budgeting formula cut disability support for thousands of people. They could neither see nor effectively challenge how their budgets were calculated.

What might have helpedThe court's findings suggest that disclosing how budgets are calculated, testing the tool to confirm it reflects people's assessed needs, and offering a real appeal with a human review could have prevented arbitrary cuts.

Partly mitigated Since thenUnder a class settlement approved in 2016, Idaho's Department of Health and Welfare agreed to build a new budget system (a 'supports budget model') with input from the ACLU, participants and families. It also agreed to let people see their assessment documents, fund representatives for budget appeals, allow increases for documented health or safety needs, and keep each participant's highest past budget in place until the new model is ready.

Still openThe ACLU of Idaho says the state has still not put a fair new system in place, and in 2024 the court appointed a Special Master to speed things up. The department's own page describes the changes as still being worked on. Participants are protected by frozen budgets rather than a fixed tool.

LessonThe case suggests that a court order to rebuild an automated tool can take years longer than planned. The interim measures, such as disclosure, funded appeals and frozen budgets, did more for the people affected than the promised new model has so far.

Sources: acluidaho.org · healthandwelfare.idaho.gov

Sources: courtlistener.com · aclu.org · healthandwelfare.idaho.gov · acluidaho.org · sources re-checked 2026-09-30

Updates: 2026-09-30: The ACLU of Idaho reports that Idaho Medicaid still had not deployed a compliant replacement budget tool years after the ruling and settlement; a special master was appointed in 2024, and the case was still active as of late 2025.

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