Research regarding treatment adherence in chronic diseases, such as hypertension, suggests that increasing complexity in the medication regimen is associated with decreasing patient adherence. However, less is known about the relationship between regimen complexity and adherence in the treatment of HIV/AIDS.To examine the relationship between antiretroviral (ART) regimen complexity and patient understanding of correct regimen dosing to adherence (missing doses in the past 1 and 3 days).Cross-sectional survey of a cohort of women living with HIV/AIDS and enrolled in the HER (HIV Epidemiologic Research) Study.Seventy-five percent of patients correctly understood the dosing frequency of their ART medications, 80% understood the food-dosing restrictions, whereas only 63% understood both. The percentage of patients with a correct understanding of dosing decreased with increasing regimen complexity (increased dosing frequency and food-dosing restrictions). Patients were more likely to have missed doses in the previous 3 days if they were taking ART medications three or more times per day or had to take one or more antiretrovirals on an empty stomach. A multivariate logistic regression model demonstrated that patients with less complex regimens (twice daily or less in frequency, no food-dosing restrictions) who correctly understood the dosing and food restrictions of their ART regimen were less likely to have skipped doses in the past three days (odds ratio [OR], 0.4; 95% confidence interval [CI], 0.2-0.7) than those with more complex regimens. Younger age and higher CD4 count were also associated with a reduced likelihood of skipping doses. No association was found between adherence and race/ethnicity, current or past injection drug use, or education.Self-reported adherence is better among patients with less complex ART regimens. This is in part because patients' understanding of regimen dosing decreases as regimen complexity increases. Therefore, simplifying antiretroviral regimens may have an important role in improving patients' adherence.
