Reduced levels of vitamin D in patients taking efavirenz
Simon Collins, HIV i-Base
Todd Brown and colleagues from Johns Hopkins University presented results from a retrospective analysis that supports a link between efavirenz and reduced levels of vitamin D. 
The study compared 25-(OH) vitamin D levels from stored samples from 87 treatment naive patients and compared this to levels 6-12 months after starting treatment containing efavirenz (n=51) or non-efavarinz (n=36; 89% PI-based).
Several studies have reported an association between NNRTIs and reduced levels of vitamin D, including a recent UK study linking low levels to the use of efavirenz. 
The current study reported a prevalence of mild, moderate and severe vitamin D deficiency at baseline in 84% (<32 ng/mL/<80 nmol/L), 56%% (<20 ng/mL/<50 nmol/L) and 33% (<15 ng/mL/< 37.5 nmol/L) patients respectively. Median levels were lower in non-white compared to white patients (16 vs 30 ng/mL, p<0.0001) and in winter compared to summer (15 vs 27 ng/mL, p<0.001).
Factors associated with low levels at baseline included race (Prevalence Ratio 6.7 95%CI: 1,7, 25.6; p=0.006), season (PR 4.6; 1.2, 17.8; p=0.03) and duration of HIV infection (PR 1.06; 1.02, 11.09; p=0.003).
Pre- and post-HAART levels in the efavirenz group dropped from 22.6 to 18.4 and increased from 21.2 to 22.9 in the non-efavirenz group (p=0.05 between group comparison post-HAART). After adjusting for baseline 25(OH)D, race and season, the adjusted mean difference between group was -5.1 +1.5 ng/mL, (p=0.001). Using the <15 nmol/mL cut-off the percentage of patients with severe depletion increased from 27% to 48% in the efavirenz group and reduced from 42% to 31% in the non-efavirenz group.
The adjusted prevalence ratio for efavirenz use was 1.8 (95%CI 1,2, 2,8, p=0.007).
No association was found with use of tenofovir, abacavir or AZT.
- Brown TT et al. Association between initiation of antiretroviral therapy with efavirenz and decreases in 25-hydroxyvitamin D. 11th Intl Workshop on Adverse Drug Reactions. 26-28 October 2009, Philadelphia. Oral abstract O-20. Antiviral therapy 2009; 14 Suppl 2: A15.
- Welz et al. Efavirenz use is associated with severe Vitamin D deficiency in a large, ethnically diverse urban UK HIV cohort. Poster abstract TUPEB186. 5th IAS conference, 19-22 July 2009, Cape Town.