Can the prognosis of polymyalgia rheumatica be predicted at disease onset? Results from a 5-year prospective study

Abstract

Objective: To identify the features of PMR that may predict the duration of steroid therapy, the occurrence of relapses and the late development of GCA.

Methods: Prospective cohort study of 176 patients with PMR, followed up for 5 years. Baseline factors associated with the duration of steroids therapy were identified using Cox regression. Predictors of relapse and the late development of GCA were identified using binary logistic regression.

Results: A total of 176 patients with PMR were included, of whom 124 stopped steroids within 5 years. The probability of stopping steroids within 5 years was independently reduced by an elevated plasma viscosity (PV) [hazard ratio (HR) = 0.49; 95% CI 0.29, 0.82 for a PV > or = 2.00 mPa s compared with a PV < or = 1.80 mPa s; overall P = 0.024] and by starting treatment at >15 mg prednisolone (HR = 0.63; 95% CI 0.41, 0.97; P = 0.036). Either of these independently reduced the chances of stopping steroids within a given time interval between 27 and 51%. No significant predictors of relapse were identified. Predictors of late GCA on univariable analysis were female sex [odds ratio (OR) = 8.16; 95% CI 1.06, 63.13; P = 0.044], HLA-DRB1*0101 or -*0401 alleles (OR = 4.95; 95% CI 1.05, 23.34; P = 0.043), PV > or = 2.00 mPa s compared with PV < or = 1.80 mPa s (OR = 10.64; 95% CI 1.28, 88.38; P = 0.029) and initial prednisolone dose >15 mg (OR = 4.53; 95% CI 1.61, 12.79; P = 0.004).

Conclusion: A higher PV in PMR increases the risk of prolonged steroid therapy and late GCA. Female sex and particular HLA alleles may increase the risk of late GCA. Starting patients on >15 mg prednisolone is associated with a prolonged steroid duration.