A Correlation Between Prognostic Nutritional Index and Sarcopenia in Patients With Rheumatoid Arthritis

Aims/Background In rheumatoid arthritis (RA) patients, malnutrition and sarcopenia are commonly associated with poor prognosis. The prognostic nutritional index (PNI), which includes serum albumin levels and lymphocyte counts, reflects the nutritional and inflammatory status of the patient. Therefore, this study aims to assess the relationship between PNI and sarcopenia in RA and examine its role as a diagnostic tool. Methods This retrospective study analysed data from 178 RA patients hospitalised at Affiliated Jinhua Hospital, Zhejiang University School of Medicine, between June 2023 and June 2025. Sarcopenia was diagnosed following the 2019 Asian Working Group for Sarcopenia (AWGS) criteria. Demographic, clinical, and laboratory data were collected, and PNI was calculated. Univariate and multivariate logistic regression analyses were performed to examine the association between PNI and sarcopenia, and receiver operating characteristic (ROC) curves were used to evaluate its diagnostic performance. Results Out of the total 178, 56 (31.5%) patients were diagnosed with sarcopenia. Multivariate regression analysis indicated lower PNI as an independent risk factor for sarcopenia (odds ratio [OR] = 0.88, 95% confidence interval [CI]: 0.80-0.97, p = 0.007), indicating that each 1-point increase in PNI was associated with a 12% decrease in risk. Older age (OR = 1.07), longer RA disease duration (OR = 1.50), and higher C-reactive protein (CRP) (OR = 1.06) were also independent risk factors. A prediction model combining age, PNI, disease duration, and CRP showed excellent discriminatory ability for sarcopenia, with an area under the curve (AUC) of 0.92 (95% CI: 0.87-0.97, p < 0.001), a sensitivity of 95.1%, and a specificity of 80.4%. Conclusion PNI is a simple, cost-effective measure that integrates nutritional (albumin) and inflammatory (lymphocyte) markers, facilitating early identification of RA patients at higher risk for sarcopenia and providing a basis for timely intervention.