Evaluation of Inflammatory Scores as Diagnostic Markers for Polymyalgia Rheumatica

OBJECTIVE: Polymyalgia rheumatica (PMR) is a chronic inflammatory rheumatic disease affecting older adults, with symptoms often overlapping with those of other conditions, thus making its diagnosis challenging. The present study evaluated the utility of laboratory-based inflammatory scores, including the systemic immune-inflammation index (SII), C-reactive protein-to-albumin ratio (CAR), albumin-to-globulin ratio (AGR), and prognostic nutritional index (PNI), as diagnostic tools for PMR and explored their association with clinical manifestations. METHODS: This retrospective study analyzed the medical records of 156 patients diagnosed with PMR and 408 diagnosed with rheumatoid arthritis (RA) between 2001 and 2021 to evaluate the diagnostic performance of inflammatory scores in distinguishing between the two conditions. Statistical analyses, including receiver operating characteristic (ROC) curve analysis and logistic regression, were used to assess the accuracy and effectiveness of the scores. RESULTS: Patients with PMR exhibited higher SII and CAR scores and lower AGR and PNI values than those with RA. CAR demonstrated the best diagnostic performance, with an area under the ROC curve (AUC) of 0.823 (95% confidence interval [CI], 0.784-0.861), followed by SII (AUC, 0.797 [95% CI, 0.757-0.837]), AGR (AUC, 0.696 [95% CI, 0.648-0.743]), and PNI (AUC, 0.691 [95% CI, 0.641-0.741]). Combining these scores improved diagnostic ability, with an AUC of approximately 0.835. Furthermore, elevated SII or CAR values and decreased AGR or PNI values were associated with leucocytosis, anemia, elevated erythrocyte sedimentation rate/C-reactive protein, hypalbuminaemia, fever, weight loss, and headache. CONCLUSIONS: Serological inflammatory scores, such as SII, CAR, AGR, and PNI, were useful as diagnostic markers for PMR, with combined scores enhancing overall diagnostic accuracy.