Objective: The aim of this study was to identify factors associated with the initiation of biologic agents for the treatment of rheumatoid arthritis (RA) in a large US observational cohort.
Methods: Semiannual patient-reported data in the ARAMIS (Arthritis, Rheumatism and Aging Medical Information System) data bank from January 1998 to January 2006 were analyzed retrospectively using pooled logistic regression (with adjustment for center-level and temporal effects) to identify patient-, disease-, and treatment-related characteristics associated with the initiation of biologics for the treatment of RA.
Results: The analysis included 1545 patients from 7 US centers. By 2006, 41.4% of 679 patients remaining in the sample had received biologics. Initiation of biologics was significantly associated with greater disability in the previous 6-month period (per 1-unit increase in Health Assessment Questionnaire score: odds ratio [OR] = 1.45; 95% CI, 1.22-1.72; P < 0.01) and treatment in the previous period with steroids (OR = 2.24; 95% CI, 1.76-2.85; P < 0.01) or nonbiologic disease-modifying antirheumatic drugs (OR = 2.43; 95% CI, 1.71-3.46; P < 0.01). Two sociodemographic factors were significant predictors of decreased use of biologics: older age (per 10 years: OR = 0.74; 95% CI, 0.660.82; P < 0.01) and lower annual income (per $10,000 reduction: OR = 0.95; 95% CI, 0.91-1.00; P = 0.04). There were no significant differences with respect to sex, race, employment status, comorbidity, previous NSAID use, or treatment center.
Conclusions: Disease- and treatment-related factors were significant predictors of the initiation of biologics for RA. Independent of these factors, however, biologics were less often used in patients who were older and those with lower incomes. Use of biologics increased steadily over the period studied.