To evaluate the positive predictive value (PPV) of 3 case definitions of rheumatoid arthritis (RA) based on self-reported data on RA diagnosis and use of arthritis medications, and to determine whether a validated screening survey would increase the PPVs in the 3 groups.
Medical records and physician checklists were reviewed for confirmation of an RA diagnosis among a sample of Black Women's Health Study participants who reported incident RA and were categorized according to reported medications: disease-modifying antirheumatic drugs (DMARDs) (n = 102), nonsteroidal antiinflammatory drugs (NSAIDs) (n = 100), and no arthritis medications (no meds) (n = 101). PPVs for confirmed RA were calculated for each of the medication groups, both overall and according to the results of the screening survey.
The PPVs of confirmed RA were 76%, 61%, and 29% in the DMARDs, NSAIDs, and no meds groups, respectively. After exclusion of women who reported other rheumatic conditions or who reported taking only prednisone, the PPV increased in the DMARDs group to 88%, but little improvement was seen in the other groups. The PPVs increased somewhat according to results of the screening survey for the DMARDs group (92% for positive screen versus 85% for negative screen; P = 1.00), and increased substantially for the NSAIDs group (89% versus 38%, respectively; P = 0.03), but only 43% of participants completed the survey.
We found that self-report of RA, along with self-reported DMARDs, is a useful case definition for identifying confirmed RA. The validated screening survey could be useful for identifying cases of confirmed RA in some, but not all, medication groups.