To determine the incidence and the clinical, laboratory, and treatment related predictors of relapse in polymyalgia rheumatica (PMR).
Using the population based resources of the Rochester Epidemiology Project, we assembled an incidence cohort of subjects with PMR first diagnosed between January 1, 1970, and December 31, 1999. For inclusion, subjects were required to fulfill 3 criteria: (1) age > or = 50 years; (2) bilateral aching and morning stiffness in neck, shoulders, or hip girdle regions; and (3) erythrocyte sedimentation rate (ESR) > or = 40 mm/h. In subjects who fulfilled the first 2 criteria but had a normal ESR, a rapid response to low dose corticosteroids (CS) served as the third criterion. Patients were followed until permanent remission, migration, or a maximum of 5 years after their incidence date. Relapse was defined as an exacerbation of PMR symptoms requiring an adjustment of CS dose (> or = 5 mg) occurring at least 30 days after the incidence date. Time to relapse was modeled using the Kaplan-Meier method. CS treatment patterns were modeled using linear and nonlinear models. Cox regression models were used to evaluate predictors of time to first and subsequent relapses.
The study population included 364 patients with a mean age of 73.4 years and 244 (67%) were women. Among the 284 patients treated with CS, a higher initial CS dose and faster CS tapering rate were significant predictors of future relapses, after adjusting for age, sex, ESR, giant cell arteritis at PMR diagnosis, and the intensity of rheumatologist care. Every 5 mg/day increase in initial CS dose was associated with a 7% increase in the risk of relapse [hazard ratio (HR) 1.07, 95% CI 1.02, 1.13]. The hazard of having a relapse was 4-fold higher when the CS tapering rate was fast (HR 4.27, 95% CI 2.84, 6.44), and 2-fold higher when the CS tapering rate was medium (HR 2.19, 95% CI 1.54, 3.11) compared to slow tapering.
Higher initial CS doses and faster tapering are significant predictors of future relapses. Our results suggest that efforts should be made to minimize initial CS dose and taper CS slowly in order to avoid disease relapses.