Vitamin D concentration and patient reported outcomes in sarcoidosis

Abstract

Sarcoidosis patients frequently have low inactive Vitamin D form levels accompanied with the increased levels of the active form due to its autonomic conversion in sarcoid granulomas. The aim of our study was to evaluate the influence of lower serum Vitamin D3 concentration on subjective disease outcomes – fatigue and depression. In the cross-sectional study the degree of fatigue and depression was measured in 400 (27.3% males) patients with pulmonary sarcoidosis. Fatigue was measured by standardized Fatigue Assessment Scale (FAS). Depression was assessed by CES-D instrument. Mean age of patients was 50.5±11 years; average duration of the disease 6.1±6.1 years; mean Vitamin D3 level was 14.2±10.2 µg/L. Mean FAS score was 21.9±6.3. Fatigue (FAS scores ≥ 22) was present in 186 (46.5%) patients. Mean CES-D scoore was 14.4±8.4. Clinically defined depression (CES-D scores ≥ 16) had 128 patients (32%). We found a significant correlation between mean Vitamin D3 levels and physical and mental component of fatigue (p=0.017 and p=0.018, respectively), but the correlation with the total FAS scores was absent. We also noticed a significant correlation between mean Vitamin D levels and CES-D scores (p=0.044). FAS score, Vitamina D3 and symptoms score were highly significant independent predictors of the depression in sarcoidosis patients. A highly significant canonic discriminative function (Wilks' Lambda=0.642; χ2=145.22; p<0.001) was found. These predictors explained 81.5% of variance of the categorical variable depression present – yes/no. It is very important to regularly measure serum Vitamin D3 levels in sarcoidosis patients since it can significantly influence subjective diseases outcomes, the depression in particular.