Factors predicting lack of adherence to highly active antiretroviral treatment

INTRODUCTION. Knowledge of adherence to highly active antiretroviral treatment (HAART) and the variables associated with poor compliance is useful for the follow-up of HIV infected patients. PATIENTS, MATERIAL AND METHODS. Patients were consecutively recruited from the HIV outpatient clinics of the Hospitals of Leon and El Bierzo from January to June 2000. Patients were considered non-adherent to treatment if they failed to take 10% or more of their prescribed total dose of at least one drug during the 4 days before the interview, or if they had accumulated a delay of more than 9 days over the previous 3 months in picking up their prescribed drugs from the hospital pharmacy. Logistic regression analysis was performed with variables found to be associated with adherence in the univariate analysis. RESULTS. The methods used to determine adherence had a Kappa index of 12.6%. Among the 206 patients interviewed, 108 were considered non-adherent (52.4%; CI 95% = 45.6-59.2). Multivariate analysis showed that the following factors were associated with poor treatment adherence: cocaine consumption in the previous six months (adjusted OR = 5.1); patients unsure about the proper way to take prescribed treatment; (adjusted OR = 2.5); and patients not prescribed the zidovudine-lamivudine combination (adjusted OR = 1.9). Over one-third of patients with no variable associated with treatment adherence were considered non-compliant. CONCLUSION. Measurement of medication adherence and its predictive factors involved methodological difficulties. With the criteria used in the present study more than half the patients were considered non-compliant. The variables found to be related to poor adherence can be modified by social, psychological or health care interventions.