Poor validation of medical record ICD-9 diagnoses of gout in a veterans affairs database

Diagnostic codes based on medical records or claims data have been used to identify patient populations with gout for important epidemiologic and clinical studies. We evaluated whether we can document the accuracy of such diagnoses by review of medical records and then on direct interviews with a subset of patients.

Electronic medical records of 289 patients with 2 visits with ICD-9 codes for gout were extensively reviewed to search for documentation of features that would classify patients as having gout by 3 sets of proposed criteria, the American College of Rheumatology (ACR), New York, or Rome criteria. Records of patients who had been seen by rheumatologists were compared with all others. A subset of patients seen in clinic were directly interviewed for comparison with the results from the records.

Based on medical records review there was documentation of gout by the ACR criteria in only 36%, Rome criteria in 30%, and New York criteria in 33%. Records of patients who had seen rheumatologists had better documentation of classification features. Interview in clinic of 37 patients also improved documentation of the 3 sets of criteria features of gout in 65%-81% of those with ICD-9 codes for gout.

We found it difficult to confirm ICD-9 coded diagnoses of gout using currently available proposed criteria from details recorded in medical records. This may reflect a problem with available criteria and with documentation. Direct interview of patients may be needed to confirm the presence of typical features when high specificity is desired.