Performance of the polymyalgia rheumatica activity score for diagnosing disease flares

To evaluate the effectiveness of the polymyalgia rheumatica activity score (PMR-AS) in diagnosing disease flares.

Rheumatologists prospectively included 89 patients with PMR (mean +/- SD age 74.6 +/- 6.2 years, mean +/- SD disease duration 1.6 +/- 2.2 years). At each visit, the rheumatologist assessed disease activity using a visual analog scale (VAS) and recorded whether a disease flare was diagnosed and/or the glucocorticoid dose changed. Overall, 137 visits including 49 pairs (allowing intraindividual comparisons) were available; a disease flare was diagnosed at 32 visits. We evaluated statistical associations linking flare diagnosis to the PMR-AS, each of its components (VAS, VAS for pain, C-reactive protein, morning stiffness, and elevation of upper limbs), and changes in these parameters between 2 visits.

Associations with disease flare diagnosis were strongest for PMR-AS scores > or =9.35 (agreement 92%, 95% confidence interval [95% CI] 85.8-95.7%, kappa = 0.78; sensitivity 96.6%, 95% CI 80.4-99.8; specificity 90.7%, 95% CI 83.2-95.2) and for DeltaPMR-AS scores > or =6.6 (agreement 98%, 95% CI 88.0-99.9%, kappa = 0.95; sensitivity 100%, 95% CI 74.7-100; specificity 97.1%, 95% CI 82.9-99.8). Other parameters showed weaker diagnostic performance.

This study supplies new evidence that the PMR-AS is useful for monitoring PMR activity in everyday practice and for managing glucocorticoid tapering. PMR activity changes seem even more relevant than absolute values.