Rheumatoid arthritis (RA) causes disability and reduced productivity. There are no large quantitative studies of earnings and productivity losses in patients with clinical RA, and no studies of household income losses. We describe methods for obtaining earnings and household income losses that are applicable to working as well as nonworking RA patients, and we perform such studies using these methods.
We estimated cross-sectional expected annual earnings and household income losses in 6,649 persons with RA from Current Populations Survey (CPS) and O*NET (Occupational Information Network) data, and we estimated expected household income and earnings losses based on demographic characteristics after adjustment to Medical Outcomes Study Short-Form 36 (SF-36) population norms (internal method). Workplace productivity was measured by the Work Limitations Questionnaire (WLQ).
27.9% of patients aged < or = 65 years considered themselves disabled after 14.6 years of RA, and 8.8% received disability benefits. Annual earnings losses ranged between USD 2,319 and USD 3,407 by the CPS and internal method (preferred), with losses of 9.3% and 10.9%. A 0.25 difference in Health Assessment Questionnaire (HAQ) score was associated with a $1,095 difference in annual earnings. Productivity losses were 6% based on work limitations identified by the WLQ. Household income loss (percentage loss) including transfer payments was USD 6,287 (11.8%) for all patients, USD 4,247 (6.9%) for employed patients, and USD 7,374 (14.8%) for nonworking patients. Among nonworking nondisabled patients aged < or = 65 years, income loss was 14.1%.
As measured by annual household income loss, the overall impact of RA is USD 6,287 (11.8%). Earnings and household income are dependent on functional status, education, age, ethnicity, and marital status. Income loss is predicted by the HAQ, HAQ-II, Modified HAQ, and SF-36.