Objective: We assessed the association between gender and mortality on antiretroviral therapy (ART) using identical models with and without sex-specific categories for weight and hemoglobin.
Design: Cohort study of adult patients on ART.
Setting: GHESKIO Clinic in Port-au-Prince, Haiti.
Participants: 4,717 ART-naïve adult patients consecutively enrolled on ART at GHESKIO from 2003 to 2008.
Main outcome measure: Mortality on ART; multivariable analyses were conducted with and without sex-specific categories for weight and hemoglobin.
Results: In Haiti, male gender was associated with mortality (OR 1.61; 95% CI: 1.30-2.00) in multivariable analyses with hemoglobin and weight included as control variables, but not when sex-specific interactions with hemoglobin and weight were used.
Conclusions: If sex-specific categories are omitted, multivariable analyses indicate a higher risk of mortality for males vs. females of the same weight and hemoglobin. However, because males have higher normal values for weight and hemoglobin, the males in this comparison would generally have poorer health status than the females. This may explain why gender differences in mortality are sometimes observed after controlling for differences in baseline variables when gender-specific interactions with weight and hemoglobin are omitted.