Objective: To evaluate the validity and reliability of the polymyalgia rheumatica (PMR) activity score (PMR-AS) for relapse diagnosis by GPs, who manage a large proportion of patients with PMR.
Methods: We used seven clinical vignettes of PMR, for which 35 rheumatologists previously made a diagnosis of relapse or no relapse with greater than 80% agreement. These vignettes were submitted to 163 general practitioners (GPs), who were asked to assess disease activity using a visual analog scale (VASph), this being the only physician-dependent component of the PMR-AS. We used the 1116 available vignette-GP combinations to assess differences in VASph assessed by GPs versus rheumatologists. We evaluated statistical associations linking a relapse diagnosis by the rheumatologists (the reference standard) to the value of the GP-assessed PMR-AS or its components (GP-assessed VASph, VAS pain score, C-reactive protein, morning stiffness, and elevation of upper limbs).
Results: We found no significant differences between VASph scores by GPs versus rheumatologists for any of the vignettes. A relapse diagnosis was strongly associated with PMR-AS≥7 (sensitivity, 99.4%; specificity, 93.3%; agreement, 95.9% [95CI, 94.5-97.0%] with κ=0.92). Of the 590 GP-vignette combinations with PMR-AS values lower 7, all but 3 (0.5%) had no relapse diagnosis. Of 510 combinations with PMR-AS values of 7 or more, only 42 (8%) had no flare diagnosis.
Conclusions: This study supports the validity of PMR-AS in primary care practice and provides evidences that a good scoring system can be useful to guide clinical and therapeutic decisions.