Background: Body mass index (BMI) can influence drug metabolism, thus affecting efficacy and risk for toxicities. Hypothesizing that persons with an increased BMI and larger volumes of distribution may experience a suboptimal response to highly active antiretroviral therapy (HAART), we evaluated the effect of BMI on virologic and immunologic response in previously ART-naive patients initiating therapy.
Methods: Using data from the HIV Outpatient Study, we analyzed the statistical association of BMI and other selected demographic variables with achieving an undetectable viral load and experiencing a CD4 cell count increase of more than 100 cell/microL after 3 to 9 months of therapy among antiretroviral-naive patients initiating HAART.
Results: Among 711 patients included in analysis, 43% had a BMI of more than 25 (overweight-obese). Higher BMI was associated with being female, having black or Hispanic race/ethnicity, being heterosexual, and using injection drugs (all P<0.001). The patients in BMI groups did not differ significantly by baseline CD4 cell count or the duration of the initial HAART regimen. Although median baseline viral loads were significantly lower in obese participants (P=0.008), overweight or obese BMI did not significantly alter the likelihood of achieving an undetectable viral load and a CD4 cell count increase of more than 100 cells/microL compared with normal weight persons.
Conclusion: A substantial proportion of HIV-infected outpatients in this cohort were overweight or obese. Increased BMI was not associated with decreased virologic and immunologic responses to initial HAART. Responses were equivalent and within expected ranges between normal weight patients, overweight patients, and obese patients at 3 to 9 months of observation.