Vitamin D deficiency and pulmonary affection in rheumatoid arthritis

Abstract

Background Vitamin D appears to play a key role both in the innate and in the adaptive immune system, and the presence of its receptors in different cell types seems to play a role in the pathogenesis of rheumatoid arthritis (RA). Vitamin D deficiency is common and seems to be correlated with the course of RA and outcome of pulmonary disease, which is a major contributor to morbidity and mortality in RA patients. Aim This study aimed to evaluate the prevalence of vitamin D deficiency and its relationship with pulmonary affection in a cohort of Egyptian RA patients. Patients and methods A total of 100 RA patients were enrolled in this study, who underwent a clinical examination, with a focus on articular and extra-articular manifestations including pulmonary manifestations. Assessment of RA disease activity was performed using the disease activity score (DAS)-28 score and serum vitamin D level was measured. Spirometry and diffusion lung capacity for carbon monoxide were performed. Radiographic evaluation, Plain x-ray on hands, chest x-ray and high-resolution computed tomography (HRCT) chest were done. Results Our study included 100 RA patients (40 patients with pulmonary affection and 60 patients without pulmonary affection). DAS-28 and rheumatoid factor titer were increased in RA patients with pulmonary affection. Moreover, vitamin D serum levels were decreased in RA patients with pulmonary affection. Multiple regression analysis showed that older age, disease activity parameters, and decreased vitamin D levels had an independent effect on increasing the HRCT chest total score. Logistic regression analysis showed that the increase in the DAS-28 score and the rheumatoid factor titer and the decrease in the vitamin D levels had an independent effect on increasing the probability of pulmonary affection occurrence. Conclusion Patients with RA-associated interstitial lung disease ‘proved by HRCT and/or diffusion lung capacity for carbon monoxide’ tend to have a high prevalence of vitamin D deficiency and high disease activity; also, lower levels of vitamin D play a significant role in the pathogenesis of RA-interstitial lung disease.