Vitamin D, which is important for calcium homeostasis and bone metabolism, has several noncalcemic actions. Low vitamin D levels have been observed in HIV-infected patients from high latitudes, with consequently reduced bone mineral density (BMD), but data from the tropics are scarce. We aimed to determine the prevalence of and risk factors for hypovitaminosis D among HIV-infected patients in the tropics. This was a cross-sectional study to determine serum 25-hydroxyvitamin D [25(OH)D] levels in HIV-infected patients who attended our HIV clinic in Bangkok, Thailand from July 2010 to June 2011. Hypovitaminosis D was defined as vitamin D insufficiency and deficiency [25(OH)D 20-30 ng/ml and <20 ng/ml, respectively]. Hypovitaminosis D prevalence was calculated and risk factors were determined using multivariate logistic regression. A total of 673 HIV-infected adults were included. The median age was 41 years and 47% were females. The median body mass index (BMI) was 21.9 kg/m(2) and 93% were using antiretroviral therapy (ART), with a median (IQR) duration of 8.9 (5.0-10.4) years. Thirty-one percent were using efavirenz (EFV). The prevalence of vitamin D insufficiency and deficiency was 40.6% and 29.9%, respectively. In multivariate analysis, female gender [odds ratio: OR (95% confidence interval: 95% CI) 1.7 (1.2-2.3), p = 0.005], age >37 years [OR (95% CI) 1.6 (1.1-2.4), p = 0.01], and EFV use [OR (95% CI) 2.0 (1.3-3.2), p = 0.004] were independent predictors of hypovitaminosis D. Even in tropical areas where the sun is abundant, hypovitaminosis D is highly prevalent. Thus, treatment of low vitamin D in HIV-infected patients at high risk should not be ignored to prevent reductions in BMD and other hypovitaminosis D-related comorbidities.
Trial registration: ClinicalTrials.gov NCT01138241.