Monday, October 25, 2010: 2:00 PM
Sheraton Hall A/B/C (Sheraton Centre Toronto Hotel)

2:00 PM
Martine Nurek, MSc, Brendan C. Delaney, MD and Olga Kostopoulou, PhD, King's College London, London, United Kingdom

Background: Cognitive factors are the most prevalent cause of diagnostic error. This systematic review aims to collate and characterize the methods that have been employed for their study.

Methods: MEDLINE, PubMed, EMBASE, PsycINFO and Web of Science were searched systematically to identify primary studies investigating the cognitive factors affecting the diagnostic performance of physicians. Studies of visual diagnostic tasks or mental health disorders were excluded.

Results: Searches identified 2742 studies of which 71 were eligible for the review. They were categorized into either 'experimental' (whereby situations for observing the behavior of interest are created by the researcher) or 'observational' (whereby situations for observing the behavior of interest are sampled from real cases). Experimental studies were subdivided into 'process-tracing' (that collect data during the diagnostic process) and 'post-hoc'. Observational studies were subdivided into 'record-based' (sampling error cases from databases) and 'clinician-based' (eliciting error cases from physicians).

Experimental (n =36)

Observational (n =35)







Insufficient Information for classification








Studies were characterized in terms of theoretical framework, potential for bias, generalisability and multiple methods. A theoretical framework to enable predictions and explain results was present in 87% of experimental studies and 14% of observational studies. Potential for bias: In experimental studies, reactivity (method could change the behavior being studied) was potentially a problem for 62% of process-tracing studies. In 71% of the post-hoc studies, bias stemmed from the use of post-hoc measures to make inferences about the diagnostic process. In a third of observational studies, there was subjectivity in the case review: a single or unspecified number of reviewers, lack of a review protocol and lack of measures of agreement. None of the clinician-based studies specified the time since the error occurred or whether the medical record was available during reporting, suggesting the potential for memory biases. Generalisability: Almost all experimental studies employed written simulations of patients. Each participant diagnosed on average 7 cases. Observational studies investigated a much larger number of diagnostic errors. However, there was substantial variation between studies in the number of records searched, cases analyzed and errors identified. Multiple methods: Only 8% of studies attempted to replicate or supplement findings through the use of multiple methods.

Conclusion: No single methodological approach is ideal for studying the cognitive causes of diagnostic error, yet multiple methodologies are rarely employed. Investigation into patterns of findings from each methodology is ongoing.

2:15 PM
Marieke De Vries, PhD, MA1, Cilia L. M. Witteman, PhD2, Leontien de Kwaadsteniet, PhD2, John Van den Bercken, PhD3, Rob W. Holland, PhD2 and Ap Dijksterhuis, PhD2, (1)Leiden University Medical Center, Leiden, Netherlands, (2)Radboud University Nijmegen, Nijmegen, Netherlands, (3)Radboud Univeristy Nijmegen, Nijmegen, Netherlands

Background: This study tests the influence of different response modes (direct, after conscious and after unconscious thinking) in clinical decision making. Recently, we published a first demonstration of unconscious thought effects in this domain, specifically in the complex and error-prone task of diagnostic classification (De Vries et al., in press). The current study describes a follow-up and refinement, in three ways. First, it investigated the role of experience by including experienced clinicians. Second, it included the degree of difficulty of classifications. Third, it included a third (control) condition in which classifications were provided immediately after reading a case description.

Methods: We used two written case descriptions. Both cases represented co-morbidity, with a more familiar classification (low difficulty) and a much more unfamiliar classification (high difficulty). Participants were randomly assigned the task in two of three response modes: conscious-processing (i.e., deliberately thinking about the information in the case description), unconscious-processing (i.e., deciding after performing an unrelated distracter task), or direct responding, without any delay or intervening task. Our main dependent measure was the proportion of correct classifications.

Results: A GLM analysis revealed a significant three way interaction, see Figure 1. For classifications low in difficulty, novices performed best after conscious processing. Experienced clinicians, in contrast, performed worst after conscious processing. For classifications high in difficulty, experienced clinicians outperformed novices. Moreover, both conscious and unconscious processing resulted in better performance than immediate classification.

Figure 1: Proportion of correct classifications as a function of Processing Condition, Difficulty and Experience Level.

Conclusion: The occurrence of diagnostic errors in psychiatric classifications appears to be a complex function of information processing mode, level of experience and task difficulty. In case of familiar classifications, experienced diagnosticians perform best when they respond either directly, or after unconscious processing, probably due to a well-developed intuition through years of practice with similar cases. Conscious thought may make them take irrelevant information into account. Novices have not had many experiences with similar cases yet, but have recently learned explicit rules for classification tasks, which may explain why they perform best after conscious thought when a classification is relatively easy. When cases become more unfamiliar, no response is directly available in memory and further –conscious or unconscious-  information processing seems to be required. De Vries et al., (in press). The unconscious thought effect in clinical decision making: An example in diagnosis. Medical Decision Making.

2:30 PM
Bradford Winters, MD, PhD1, Jason W. Custer, MD2, Atul Nakhasi, B.S.3, Victoria Goode, B.A.3, Karen Robinson, B.S.3, David E. Newman-Toker, MD, PhD4 and Peter J. Pronovost, MD, PhD, FCCM3, (1)The Johns Hopkins University School of Medicine, Baltimore, MD, (2)University of Maryland, Baltimore, MD, (3)Johns Hopkins University School of Medicine, Baltimore, MD, (4)Johns Hopkins University, Baltimore, MD

Background: : Diagnostic errors represent an important source of potentially preventable morbidity and mortality in hospitalized patients. Intensive care unit (ICU) patients may be at high risk for misdiagnosis because of high acuity and complexity of care. The spectrum of diagnostic errors in adult ICU populations is not well defined.  

Methods:  Objective─Estimate the frequency, severity, and principal causes of diagnostic error in adult ICU patients. Design─Systematic review of observational studies. Electronic (MEDLINE, EMBASE) and manual (references of eligible articles) search for articles (1960-2009). Terms (MeSH and Emtree) used included ICU, critical care, intensive care; AND diagnostic error, misdiagnosis, diagnostic delay, diagnostic error; AND necropsy, autopsy. Inclusions─Studies of ≥10 adult ICU patients with diagnostic errors confirmed by autopsy were included. Two independent reviewers selected studies, with differences adjudicated by a third. Patient characteristics, error rates, and error classes (using Goldman criteria for autopsy misdiagnoses) were abstracted.  Differences were resolved by consensus.

Results: We examined 202 citations and reviewed 76 articles. 35 studies were included. Principal reasons for exclusion were lack of original data and lack of ICU-specific data.  The 35 studies reported on diagnostic errors in 8,712 autopsies performed among 13,030 ICU deaths.  For studies that provided both the number of deaths and the number of autopsies performed (30 studies), the average autopsy rate was 29% (range=3.7%-96%).  A total of 1625 misdiagnoses were reported (19% of autopsies) with 1148 providing sufficient information to assign a Goldman class.  Of these, Goldman Class I errors (major, likely lethal) were reported in 258 (22.5%), with a range of diagnoses being missed. Infection was the most common Class I error (8 studies) followed by pulmonary embolism (6 studies) in studies reporting these data. Class II errors (major, likely non-lethal) were identified in 501 (43.6%).  Infection was again the most common (8 studies) followed by malignancy (4 studies). Minor Class III and IV errors were found in 233 (20.3%) and 156 (13.6%) cases.  

Conclusion: Our results suggest that misdiagnosis in the adult ICU population may be a frequent occurrence. A major likely lethal diagnostic error is found in one-fifth of autopsied cases. It is uncertain whether autopsy data over- or underestimate the frequency or severity of diagnostic errors but the most frequent major diagnostic errors appear related to misdiagnosed infections. Further research is needed to better quantify diagnostic errors and to define potential strategies to reduce their frequency or mitigate misdiagnosis-related harm in the adult ICU.

2:45 PM
Anne Matlow, MSc, MD, FRCPC1, Catherine M. G. Cronin, MD, MBA, FRCPC, FRCPI, FAAP2, Virginia Flintoft, MSc, BN3, Cheri Nijssen-Jordan, MD, MBA4, Mark Fleming, MA, MSc, PhD5, Barbara Brady-Fryer, BSc, MN, PhD, RN6, Mary-Ann Hiltz, CHIM, MHA Candidate7, Elaine Orrbine8 and G. Ross Baker, PhD3, (1)Hospital for Sick Children, Toronto, ON, Canada, (2)University of Manitoba, Winnipeg, MB, Canada, (3)University of Toronto, Toronto, ON, Canada, (4)Alberta Health Services, Calgary, AB, Canada, (5)St Mary's UNiversity, Halifax, NS, Canada, (6)Grant MacEwan University, Edmonton, AB, Canada, (7)IWK Health Centre, Halifax, NS, Canada, (8)Canadian Association of Paediatric Health Centres (CAPHC), Ottawa, ON, Canada
Diagnostic Errors are Common Causes of Adverse Events in Hospitalized Canadian Children.

Background: Diagnostic errors are frequent and are known to cause adverse events (AEs).  The scope of this problem in paediatrics has not been addressed.  

Methods: While validating the Canadian Association of Paediatric Health Centres’ Paediatric Trigger Tool, all AEs detected were categorized by age group (4 groups: 0-28 days, 29-365 days,>1-5 yrs and >5- 18 yrs), contributory factors (eg: surgical, diagnostic), associated mortality, etc.  Of the 591 charts reviewed, 89 patients (15.1%) had AEs. This paper analyzes these events.

Results:  Diagnostic AEs (DAEs) occurred in 14 of 89 patients with AEs (15.7%) and 11.4% of all AEs (14/123) were diagnostic. DAEs were more common in children <1 year of age (8/298=2.7%) than in those >1 -18 years (6/ 293=2.0%).  However DAEs accounted for more of the AEs in children >5 years vs <5 (3/16= 18.8% vs 11/107=10.3%). Of DAEs 50% were infections and 14.3% (2/14) of patients with DAEs died vs 2.7% (2/75) of those without DAEs. All deaths were in neonates.
Age Group # DAEs Percent of AE patients w/DAE -                                     % (n DAE/n All) DAEs as Percent of All AEs                                                      % (n DAE/n All AE)   
0-28 days 4 12.12   (4/33)  5.36 (4/56)   
29-365 days 4 19.05   (4/21)  14.81 (4/27)  
>1-5 years 3 5.55     ( 3/54)  12.5 (3/24)  
>5 years 3 16.66   (3/18) 18.75  (3/16) 

Conclusion: DAEs are an important cause of morbidity in hospitalized children, with potentially severe consequences in neonates. Infections are more common DAEs in children than in adults.  The visibility of DAEs as a significant patient safety concern in pediatrics must be heightened in order to understand, identify and prevent them in the future.