Accuracy of the Safer Dx Instrument to Identify Diagnostic Errors in Primary Care

J Gen Intern Med. 2016 Jun;31(6):602-8. doi: 10.1007/s11606-016-3601-x. Epub 2016 Feb 22.


Importance: Diagnostic errors are common and harmful, but difficult to define and measure. Measurement of diagnostic errors often depends on retrospective medical record reviews, frequently resulting in reviewer disagreement.

Objectives: We aimed to test the accuracy of an instrument to help detect presence or absence of diagnostic error through record reviews.

Design: We gathered questions from several previously used instruments for diagnostic error measurement, then developed and refined our instrument. We tested the accuracy of the instrument against a sample of patient records (n = 389), with and without previously identified diagnostic errors (n = 129 and n = 260, respectively).

Results: The final version of our instrument (titled Safer Dx Instrument) consisted of 11 questions assessing diagnostic processes in the patient-provider encounter and a main outcome question to determine diagnostic error. In comparison with the previous sample, the instrument yielded an overall accuracy of 84 %, sensitivity of 71 %, specificity of 90 %, negative predictive value of 86 %, and positive predictive value of 78 %. All 11 items correlated significantly with the instrument's error outcome question (all p values ≤ 0.01). Using factor analysis, the 11 questions clustered into two domains with high internal consistency (initial diagnostic assessment, and performance and interpretation of diagnostic tests) and a patient factor domain with low internal consistency (Cronbach's alpha coefficients 0.93, 0.92, and 0.38, respectively).

Conclusions: The Safer Dx Instrument helps quantify the likelihood of diagnostic error in primary care visits, achieving a high degree of accuracy for measuring their presence or absence. This instrument could be useful to identify high-risk cases for further study and quality improvement.

Keywords: diagnostic error; diagnostic safety; measurement; patient safety; primary care; quality improvement.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Diagnostic Errors / statistics & numerical data*
  • Diagnostic Tests, Routine / standards
  • Humans
  • Medical Records
  • Patient Safety / standards
  • Patient Safety / statistics & numerical data
  • Predictive Value of Tests
  • Primary Health Care / standards*
  • Quality Improvement*
  • ROC Curve
  • Retrospective Studies
  • Sensitivity and Specificity
  • Texas