What’s New in the Patient Safety World

March 2013

Diagnostic Error in Primary Care



One of the diagnostic errors we’ve talked about most frequently is the missed diagnosis due to failure to follow up on test results. But is that the most frequent type of error seen in primary care? If the source of statistics about diagnostic error is primarily malpractice claims and settlements it might be the most frequent type of error. But such data sources may be somewhat misleading. In fact, a new study (Singh 2013) suggests it is not the most common diagnostic error in primary care.


Singh and colleagues have just published a remarkable study on diagnostic errors in primary care that is very enlightening. They used a trigger tool methodology (See our Patient Safety Tips of the Week for October 30, 2007 “Using IHI's Global Trigger Tool” and April 15, 2008 “Computerizing Trigger Tools” and our What’s New in the Patient Safety World columns for January 2011 “No Improvement in Patient Safety: Why Not? and May 2011 “Just How Frequent Are Hospital Medical Errors?” on using the trigger tool methodology). The triggers they used to identify cases for manual review were: (1) a primary care index visit followed within 14 days by an unplanned hospital admission and (2) a primary care index visit followed within 14 days by one or more primary care visits, emergency department visits or urgent care visits. Cases identified by these triggers were then manually reviewed by trained experienced clinical reviewers for the occurrence of diagnostic errors. They found diagnostic errors in 20.9% of cases identified by the first trigger and 5.4% identified by the second trigger, compared to 2.1% in control cases.


They found that patients involved in cases with diagnostic errors were slightly older (66.5 years on average compared to 62.7 years). That should not be particularly surprising. We know that, in general, medical errors tend to occur more often in older patients probably as a result of a number of factors, including more comorbidities, more medications, and other variables.


The diagnoses that were “missed” were not “zebras” or relatively uncommon or complex diagnoses but rather very common diagnoses and conditions (eg. pneumonia, decompensated CHF, acute renal failure, cancer, UTI, etc.). That is similar to results of another study on diagnostic errors in primary care (Ely 2012) that we discussed in our May 15, 2012 Patient Safety Tip of the Week “Diagnostic Error Chapter 3”. The nature of the presenting symptoms was not particularly remarkable with the exception that a significant number of patients did not have a specific presenting complaint (eg. those presenting for followup of their chronic conditions or those having a first visit to establish ongoing care).


While breakdowns were seen in all dimensions of the diagnostic process (and often involved more than one dimension) breakdowns most often occurred during the patient-practitioner clinical encounter and most often involved cognitive errors in data-gathering or synthesis. These included items related to medical history, physical exam, ordering diagnostic tests or failure to review prior documentation. Interestingly, there was no documentation of differential diagnosis in over 80% of cases with diagnostic errors. And another unintended consequence of technology: they found that copying and pasting previous progress notes was frequently associated with errors.


They also did find errors related to referrals, failure to follow up on diagnostic tests and interpretation of diagnostic tests.


The authors note that their methodology, specifically the short time frame for the trigger tools, likely biased the resulting types of errors toward more acute conditions rather than more chronic conditions. Nevertheless, the study really shows that diagnostic errors are very common in primary care visits and occur across the broad spectrum of conditions seen in primary care practices.


The accompanying editorial by Newman-Toker and Makary (Newman-Toker 2013) uses the statistics from the Singh study plus those from autopsy-related studies on diagnostic errors to suggest that more than 150,000 patients per year in the US might have suffered misdiagnosis-related harm.


Singh and colleagues make several salient points about interventions to prevent diagnostic errors. First, given the wide variety of conditions and presenting symptoms they found in their study it is very unlikely that focusing solely on specific presentations will be successful in reducing overall errors. They note that most of the breakdowns occurred in the clinical encounter, perhaps with time pressures and short encounters contributing to inadequate decision making. Further yet they note that the trend toward team care and the patient-centered medical home may not result in the level of cognitive support needed for complex decision making. And the current levels of technological decision support for diagnosis are not readily available in most of today’s electronic medical records.


This is a really good study that highlights both the frequency and breadth of the problem of diagnostic error in primary care. It clearly points out how much needs to be done going forward.


See our many prior Patient Safety Tips of the Week on diagnostic error:


·        September 28, 2010     Diagnostic Error

·        November 29, 2011     More on Diagnostic Error

·        May 15, 2012              Diagnostic Error Chapter 3

·        May 29, 2008             If You Do RCA’s or Design Healthcare Processes…Read Gary Klein’s Work”)

·        August 12, 2008           Jerome Groopman’s “How Doctors Think”)

·        August 10, 2010           It’s Not Always About The Evidence

·        January 24, 2012          Patient Safety in Ambulatory Care

·        October 9, 2012          Call for Focus on Diagnostic Errors







Singh H, Giardina TD, Meyer AND, et al. Types and Origins of Diagnostic Errors in Primary Care Settings. JAMA Intern Med 2013; published online February 25, 2013




Ely JW, Kaldjian LC, D’Alessandro DM. Diagnostic Errors in Primary Care: Lessons Learned. J Am Board Fam Med 2012; 25: 87–97




Newman-Toker DE, Makary MA. Measuring Diagnostic Errors in Primary Care. Comment on “Types and Origins of Diagnostic Errors in Primary Care Settings”. JAMA Intern Med 2013; published online February 25, 2013







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