To determine the validity of self-reported physician diagnosis of rheumatoid arthritis (RA) using multiple gold-standard measures based on Medicare claims in a nationally representative sample of older adults and to verify whether additional questions about taking medication and having seen a physician in the past two years for arthritis can improve the positive predictive value (PPV) and other measures of the validity of self-reported RA.
A total of 3768 Medicare-eligible respondents with and without incident self-reported RA were identified from the 2004, 2008, and 2012 waves of the United States Health and Retirement Study. Self-reported RA was validated using the following three claims-based algorithms: 1) a single International Classification of Diseases, ninth edition, Clinical Modification claim for RA, 2) two or more claims no greater than 2 years apart, and 3) two or more claims with at least one diagnosis by a rheumatologist. Additional self-report questions of medication use and having seen a doctor for arthritis in the past two years were validated against the same criteria.
A total of 345 respondents self-reported a physician diagnosis of RA. Across all three RA algorithms, the PPV of self-report ranged from 0.05 to 0.16., the sensitivity ranged from 0.23 to 0.55., and the κ statistic ranged from 0.07 to 0.15. Additional self-report data regarding arthritis care improved the PPV and other validity measures of self-report; however, the values remained low.
Most older adults who self-report RA do not have a Medicare claims history consistent with that diagnosis. Revisions to current self-reported RA questions may yield more valid identification of RA in national health surveys.