Administrative database code accuracy did not vary notably with changes in disease prevalence.
Previous mathematical analyses of diagnostic tests based on the categorization of a continuous measure have found that test sensitivity and specificity varies significantly by disease prevalence. This study determined if the accuracy of diagnostic codes varied by disease prevalence.



We used data from two previous studies in which the true status of renal disease and primary subarachnoid hemorrhage, respectively, had been determined. In multiple stratified random samples from the two previous studies having varying disease prevalence, we measured the accuracy of diagnostic codes for each disease using sensitivity, specificity, and positive and negative predictive value.



Diagnostic code sensitivity and specificity did not change notably within clinically sensible disease prevalence. In contrast, positive and negative predictive values changed significantly with disease prevalence.



Disease prevalence had no important influence on the sensitivity and specificity of diagnostic codes in administrative databases.
Department of Medicine, University of Ottawa, 501 Smyth Road, Ottawa K1H 8L6, Canada; Clinical Epidemiology Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa K1H 8L6, Canada; Institute for Clinical Evaluative Sciences, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada. Electronic address: carlv@ohri.ca.
Carl
C
van Walraven
Department of Medicine, University of Ottawa, 501 Smyth Road, Ottawa K1H 8L6, Canada; Clinical Epidemiology Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa K1H 8L6, Canada.
Shane
S
English
Institute for Clinical Evaluative Sciences, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada; Institute for Health Policy, Management and Evaluation, University of Toronto, 155 College Street, Toronto, Ontario M5T 3M6, Canada; Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada.
Peter C
PC
Austin
D016208:Databases, Factual / Q000706:statistics & numerical data*; D003955:Diagnostic Tests, Routine / Q000706:statistics & numerical data*; D006801:Humans; D015995:Prevalence; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis* / Q000453:epidemiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis* / Q000453:epidemiology*
Accuracy; Administrative data; Diagnostic code; Negative predictive value; Operating characteristics; Positive predictive value; Prevalence; Sensitivity; Specificity