Physician Global Assessment as a Disease Activity Measure for Relapsing Polychondritis.

OBJECTIVE Relapsing polychondritis (RP) is a systemic inflammatory disorder of cartilage that lacks validated disease activity measures. Physician global assessment (PhGA), a measure of disease activity commonly used in rheumatologic diseases, has not been tested in a cohort of patients with RP. METHODS Adult patients in an observational cohort of RP underwent standardized, comprehensive evaluation at approximately 6-month intervals. PhGA was scored by three physicians from the evaluating institution on a scale of 0 to 10 for each visit. A random subset of twenty visits was scored by three, independent physicians not affiliated with the evaluating institution. Treatment change between consecutive visits was categorized as increased, decreased or unchanged. RESULTS 78 patients were evaluated over 164 visits. The interclass correlation coefficient (ICC) (2, 1) for the three raters from the evaluating institution was excellent (0.79, 95% CI: 0.73-0.84) but was poor in the subset of cases scored by the additional raters (ICC (2,1) = 0.27, 95% CI: -0.01-0.53). Median PhGA was 3 (range 0-7). PhGA weakly correlated with CRP (rs = 0.30, p< 0.01). In response to increased treatment, median PhGA decreased from 3 (IQR: 2-4) to 2 (IQR: 2-3) (p< 0.01) but rarely went to 0. CONCLUSION Within a single-center, PhGA can be used to quantify disease activity and monitor disease response in RP. Persistent disease activity despite treatment, rather than a relapsing-remitting pattern, is observed for most patients with RP. Reliability of PhGA may not generalize across different institutions. A validated disease-specific activity index is needed in RP.