Prevalence and factors associated with vitamin D deficiency among adult patients with tuberculosis admitted on the pulmonology wards of Mulago Hospital

Abstract

Introduction: Tuberculosis is one of the commonest infections and cause of morbidity and mortality in Sub Saharan Africa. Low levels of vitamin D have been observed in African populations especially among tuberculosis patients despite the presence of abundant sunshine. Currently, there is adequate evidence that vitamin D deficiency is highly associated with tuberculosis and vitamin D plays a vital role in improving anti tuberculosis immunity, reducing progression and severity of tuberculosis in humans. Objective: This study was conducted in order to determine the prevalence and factors associated with vitamin D deficiency among adult tuberculosis patients admitted on the pulmonology wards of Mulago national referral and teaching hospital. Methods: This was a cross sectional study with an analytical component which was carried out among adult tuberculosis patients admitted on the pulmonology wards of Mulago National referral and Teaching hospital. Two hundred sixty eligible consenting adults with a confirmed diagnosis of tuberculosis were consecutively enrolled into the study. Predictor variables included age, gender, marital status, educational level, place of residence, occupation, smoking status, HIV sero status, Diabetes Mellitus , liver dysfunction , renal dysfunction, body mass index, corrected calcium levels, hemoglobin levels, mean cell volume, parathyroid hormone levels and albumin. The outcome variable was low serum vitamin D levels of ≤ 20 ng/ml. Study instruments included a social demographic questionnaire, standard measurements and assessment of serum vitamin D levels, serum calcium, albumin, creatinine, urea, alanine phosphatase (ALP) and alanine transaminase (ALT) levels, Para Thyroid Hormone levels, CD4 count for HIV positive patients, random blood sugar (RBS) level and a complete blood count. Multivariate analysis was done to determine which factors that independently predicted vitamin D deficiency. A p-value of less than 0.05 was considered statistically significant. Results: The prevalence of vitamin D deficiency among adult TB patients admitted on the pulmonology wards of Mulago national referral and teaching hospital was 44.2%. Majority of the hospitalized TB patients (n=208, 80%) had HIV co-infection. Factors significantly associated with vitamin D deficiency at multi-variate analysis were corrected serum hypocalcaemia (p-value<0.001, AOR 2.9, 95% CI. 1.70-4.91) and hypoalbuminemia (p-value=0.004, AOR 6.4, 95% CI. 1.82-22.78). Conclusion: Vitamin D deficiency is very common among adult TB patients admitted on the pulmonology wards of Mulago national referral and teaching hospital. Significant clinical predictor variables of vitamin D deficiency among admitted adult TB patients were corrected serum hypocalcaemia and hypoalbuminemia. Routine screening for vitamin D deficiency in the presence of the above among admitted adult TB patients should be adopted by clinicians in TB care programs. Due to the high prevalence of vitamin D deficiency among adult TB patients in our setting, well designed clinical trials to assess the benefit of oral vitamin D and calcium supplementation on clinical and immunological outcomes are justified.