The association between vitamin D serum level and the development of sarcopenia in psoriatic arthritis patients

Abstract Background Sarcopenia represents a health burden in patients with autoimmune rheumatological diseases. Though the etiology of sarcopenia is still obscure, vitamin D plays a pivotal role in its pathogenesis. This work aimed to assess sarcopenia in psoriatic arthritis (PsA) patients and find its relation to serum levels of 25 hydroxy vitamin D (25(OH)D). Methodology: This cross-sectional study included 43 PsA patients. Serum 25(OH)D was measured. Disease activity in PsA (DAPSA) was calculated. The Criteria of the European working Group on Sarcopenia in Older People were used for sarcopenia assessment. Muscle strength was measured using hand grip dynamometer. Muscle mass was detected using bioelectric impedance analysis, and accordingly skeletal muscle index was calculated. Physical performance was estimated with timed up and go test. Patients were divided into sarcopenic and non-sarcopenic and further classified according to degree of sarcopenia severity. Regression analysis was performed to stratify risk factors predictive of sarcopenia. Results: Patients’ mean age was 56.44 ± 7.75 years; the Female: male ratio was 3:1, and 65% of patients had sarcopenia. Serum 25(OH)D levels were statistically significantly less in sarcopenic compared to non-sarcopenic PsA patients (10.1 and 33.1 ng/ml, P < 0.001). Also, a significant statistical difference regarding each of muscle strength, mass and physical performance was found between the two groups ( P < 0.001). Univariate regression analysis revealed that longer disease duration, higher DAPSA scores and lower serum 25(OH)D levels were all significant risk factors for sarcopenia in PsA patients. However, with multivariate analysis, 25(OH)D remained a single significant independent predictor for sarcopenia development in PsA patients ( P < 0.001). Conclusion: Sarcopenia is prevalent in PsA patients and associated with low serum 25(OH)D levels, long disease duration and high disease activity. Deficient vitamin D was predictive of sarcopenia in PsA patients. Early screening for sarcopenia, vitamin D fortification and disease control are possible preventive factors for sarcopenia development in PsA patients.