Association between initiation of antiretroviral therapy with efavirenz and decreases in 25-hydroxyvitamin D

Background: We aimed to determine whether antiretroviral therapy (ART) initiation with efavirenz (EFV) is associated with decreases in 25-hydroxyvitamin D (25[OH]D) compared with non-EFV regimens. Methods: 25(OH)D was measured from stored plasma samples in 87 ART-naive HIV-positive patients prior to ART initiation with EFV-containing (n=51) or non-EFV-containing (89% with protease inhibitors; n=36) regimens from a single clinic in Cleveland (OH, USA). A repeat measurement was made 6-12 months after ART initiation. The change in 25(OH)D after ART initiation and the prevalence of patients with hypovitaminosis D (≤37.5 nmol/l [15 ng/ml]) after ART initiation was compared in those who initiated ART with and without EFV using multivariable linear and modified Poisson regression, respectively. Results: Prior to ART initiation, the median (interquartile range [IQR]) 25(OH)D concentration was 52.7 nmol/l (IQR 32.2-72.1), with 33% prevalence of hypovitaminosis D. After 6-12 months of ART, 25(OH)D decreased by a mean ±se of -12.7 ±3.7 nmol/l in the EFV group relative to the non-EFV group (P=0.001) after adjustment for baseline 25(OH)D concentration, race and season (non-summer versus summer) at the visit 6-12 months after ART initiation. Similarly, after multivariable adjustment, the risk of hypovitaminosis D after ART initiation was significantly higher in the EFV group compared with the non-EFV group (prevalence ratio 1.8 [95% confidence interval 1.2-2.8]; P=0.007). Conclusions: ART initiation with EFV is associated with significant decreases in 25(OH)D and an increased risk of hypovitaminosis D compared with non-EFV regimens.