Identification of Rheumatoid Arthritis Patients Using an Administrative Database: A Veterans Affairs Study

摘要

The accuracy of the diagnosis is vital when administrative databases are used for pharmacoepidemiologic and outcome studies. Data pertaining to the utility of databases for rheumatoid arthritis (RA) is sparse and variable. We assessed the utility of various diagnostic algorithms to identify RA patients within the Veterans Health Administration (VHA) databases.Using the ICD code for RA at two visits, at least six months apart, we identified 1779 patients between 10/1/1998 and 9/30/2009 in our local Veteran Affairs Medical Center administrative database. Disease Modifying Anti Rheumatic Drugs (DMARD) use was ascertained from the pharmacy database. Cases were analyzed based on DMARD therapy and RA codes at clinic visits. 543 patients' medical records selected by stratification and random selection on the basis of their visits were reviewed to ascertain the clinicians' diagnoses and clinical criteria documentation. Positive predictive values (PPV) were calculated for various database case identification algorithms using diagnosis of RA by medical record review as the gold standard.PPV for identification of RA with two RA codes six months apart was 30.9%. Addition of DMARD therapy increased the PPV to 60.4%. The PPV further increased to 91.4% when having RA code at the last VAMC rheumatology clinic visit criterion was added.An algorithm using only two administrative RA codes six months apart had a low PPV for correctly identifying patients with RA in the VHA database. Including DMARD therapy and requiring a RA code at the last visit with a rheumatologist increased the performance of the data extraction algorithm.