Diagnostic error: Types and causes

ANNE M. MENKE, RN, PhD, OMIC Risk Manager

In September 2014, the ophthalmologists who compose OMIC’s Claims Committee noticed an increase in OMIC malpractice cases alleging diagnostic error and asked risk management staff to explore the reasons behind this apparent trend. We looked at OMIC claims that were resolved over the seven-year period from 2008 to 2014 and presented this data at the OMIC Forum at the 2015 AAO annual meeting in Las Vegas. Many of our policyholders were not able to attend the Forum, so we are pleased to share this information from the “OMIC study” in the Digest.

The prevalence of diagnostic error has been estimated to range from 10 to 15% of patients in one study¹ and 7 to 17% of patients in another.² These errors often lead to lawsuits. A study that examined claims payments reported to the National Practitioner Data Bank (NPDB) found that diagnostic error was the most common cause of claims payments (29% of all claims), and that diagnostic error claims were the most expensive (35% of money paid) and most harmful to patients.³ Another study reviewed claims in a data sharing project and found that 20% of all claims involved an allegation of diagnostic error, accounting for 35% of claims payments.⁴ The PIAA, a trade group whose members provide medical professional liability insurance, found that diagnostic error was the most frequent cause of member reported claims between 2004 and 2013 with the highest average indemnity payment.⁵ In the PIAA study of only ophthalmology-related claims (not including OMIC’s claims) since 2004, diagnostic error was the third most frequent allegation against ophthalmologists. Payments were made in 38% of these ophthalmology-related diagnostic error claims.⁶

OMIC claims alleging diagnostic error

We found a smaller percentage of diagnostic error claims in the OMIC study compared with the other studies discussed above. Of the 1613 claims reviewed, 223 alleged a diagnostic error, accounting for 14% of the claims. We paid indemnity on a lower percentage of diagnostic error claims (28%), but these payments account for a similar percentage (34%) of total money paid to settle claims. When compared to all OMIC claims during the period, claims based on allegations of diagnostic error resulted in more paid claims, a higher median and mean payment, and the highest payment (Table 1). Of these diagnostic error claims, cornea claims had the highest percentage settled, while retina claims were the most frequent, had the highest number settled, and the highest total amount paid (Tables 2 and 3). Endophthalmitis diagnostic error claims are costly to settle; the lowest amount paid for these claims was $145,000. But oncology claims stand out as the top diagnostic error payment as well as the highest mean and median payments. There were no paid claims for diagnostic error in neuro, orbit, or uveitis.

Clinical categories of OMIC diagnostic error claims

When we look at the clinical categories of diagnostic error claims, retina claims far exceed all other types in both number and percentage of claims (Table 4). Glaucoma, medical, oncology, and cornea claims each represent 12% of these claims. Since ophthalmologists have many questions about endophthalmitis prophylaxis and patients tend to have poor outcomes, we made this a separate category. We will now briefly examine the clinical categories, in descending order of frequency. The table gives both the number of patients and claims. This is because the plaintiff (patient) may sue more than one physician (e.g., both the comprehensive ophthalmologist and the retina specialist) as well as a group practice or surgery center.

Retina claims. 84 retina claims account for 38% of all OMIC diagnostic error claims during this seven-year period. By far, the most frequently missed diagnosis in our entire study was retinal detachment (RD). These 65 RD claims represent 79% of the retina claims and 48% of the retina payments. The next issue of the Digest will explore these RD claims in detail. While there were only six claims for failure to diagnose retinopathy of prematurity (ROP), these claims compose 47% of the retina payments. There were three age-related macular degeneration claims. The remaining nine claims alleged failure to diagnose retinitis, bilateral acute retinal necrosis (BARN), branch retinal artery occlusion (BRAO), foreign bodies, and a macular hole.

Glaucoma claims. There were 27 claims alleging failure to diagnose glaucoma. Types of glaucoma include primary open angle glaucoma (11 claims, 5 payments), steroid-induced glaucoma (7 claims, 3 payments), narrow angle glaucoma (6 claims, 2 payments), and miscellaneous types (iridocorneal endothelial syndrome or ICE, neovascular, and phacolytic, all of which closed without a payment).

Medical (systemic illness) claims. There were 27 claims where a systemic illness presented with ophthalmic signs and symptoms. The most common of the medical conditions was giant cell arteritis or GCA (11 claims, 6 payments). We addressed these GCA claims in detail in the Digest last year (V25, N3 at omic.com in the Publications section). Systemic infections accounted for seven claims and one payment. Types included subacute bacterial endocarditis and sepsis. Although endogenous endophthalmitis is a systemic condition, we assigned those six claims to the endophthalmitis category. Failure to diagnose a cerebral vascular accident was alleged in five claims, and resulted in three payments.

Oncology claims. There were 27 claims. Failure to diagnose melanoma resulted in six claims and two payments. Pituitary tumors were allegedly missed in four claims but no payments were made. A delay in diagnosing glioma led to three claims and two payments, including a settlement of $2,000,000, the largest one in the study. There were three lacrimal cancer claims with one payment, three optic nerve tumors with no payments, and one trigeminal schwannoma claim, which settled for $1,000,000. We will explore the reasons for these expensive oncology claims and how to prevent them in an issue of the Digest later this year.

Cornea claims. Of the 26 claims, 17 alleged failure to diagnose an infection, leading to six payments. Please see the Closed Claim Study in this issue for a discussion of the challenges in correctly identifying the cause of a corneal infection. There were four keratoconus claims with two payments and four corneal ulcer claims with three payments. This category had the highest percentage of paid claims.

Endophthalmitis claims. There were 17 claims. In six claims, the patient had endogenous endophthalmitis, resulting in three payments. The other cases occurred following trauma (five claims, three payments), cataract surgery (three claims, no payments), and other conditions (one each in a drug user and following pterygium and strabismus surgery, none of which resulted in payments).

Standard of care evaluation of diagnostic error

As part of the investigation of a claim, both plaintiff and defense attorneys hire experts to review the medical records and allegations in order to determine if the standard of care (SOC) was met. To help us indentify areas of concern, we compared the SOC analysis provided by defense experts (Table 5). Of the 223 claims, 194 were reviewed by defense experts. OMIC-insured ophthalmologists were deemed to have met the standard of care in 112 claims (58%). The standard of care was not met or reviews were mixed (considered together as negative reviews) in 82 (42%) of the claims. While some categories had too few claims to draw any conclusions, we are concerned about the rate of negative reviews in oncology, glaucoma, medical, retina, cornea, and endophthalmitis. Our experts noted that the conditions that were improperly diagnosed were rarely exotic or unusual. They found that the evaluation was often inadequate (insufficient history, exam, or testing) and that results of some tests were misinterpreted. They also reported that ophthalmologists often had poor recognition of a worsening or non-responsive condition, and accordingly, did not obtain a second opinion or refer to a specialist in a timely fashion.

Factors impacting the diagnostic process

The diagnostic process is complex, impacted by many factors. These are often divided into three categories: physician (knowledge, skill, etc.), patient (condition and behavior), and system (appointment scheduling process; regulations; insurance rules; drug manufacture, ordering, and administration, etc.).^4,7 We analyzed factors in claims where the experts felt that the standard of care was not met. The results are shown in Table 6. Physician factors impacted 71 out of 82 claims (87%), patients had no impact, and system issues figured in 11 claims (13%). Please see the Hotline for recommendations on addressing the physician’s role in the diagnostic process.

Our study of 223 diagnostic errors during a seven-year period validated the concerns raised by our Claims Committee. While we present some recommendations on how to reduce these claims in this issue’s Hotline, it is clear that there is no quick or easy solution. Dr. George Williams, OMIC’s new Board Chair, recently met with all OMIC staff members and informed us that his focus during his tenure will be patient safety, including the risk posed by diagnostic error. We will continue to study diagnostic error in the Digest this year and in presentations we give at state society and subspecialty meetings.

Graber ML et al. “Cognitive interventions to reduce diagnostic error: A narrative review.” BMJ Qual Saf. 2012; 21: 535-557.
National Academies of Sciences, Engineering, and Medicine. “Improving diagnosis in health care.” Washington, DC: The National Academies Press. 2015.
Saber Tehrani AS et al. “25-year summary of US malpractice claims for diagnostic errors 1986-2010: An analysis from the National Practitioner Data Bank.” BMJ Qual Saf. 2013; 22: 672-680.
Hoffman J, ed. “2014 Benchmarking Report: Malpractice risk in the diagnostic process. Crico Strategies.”
PIAA. “Closed Claim Comparative.” 2014.
PIAA. “Specialty Specific Series: Ophthalmology.” 2014.
Gandhi TK et al. “Missed and delayed diagnoses in the ambulatory setting: A study of closed malpractice claims.” Ann Intern Med. 2006; 145: 488-496.