[Adherence to antiretroviral therapy measured by pill count and drug serum concentrations. Variables associated with a bad adherence]. / Adherencia a los fármacos antirretrovirales medida por la concentración de fármacos y el recuento de comprimidos. Variables relacionadas con una mala adherencia.

ABSTRACT

BACKGROUND: We aimed at measuring the adherence to HAART by means of pill count and drug plasma levels. In addition, we aimed at determining variables associated with suboptimal adherence. PATIENTS AND METHOD: Prospective observational study of 202 consecutive patients with HIV infection who were receiving antiretroviral treatment, followed up during 9 months. At baseline and at the end of the study a structured questionnaire was administered and a review of medical charts was performed. The adherence was assessed by monthly pill count while drug plasma levels were measured every three months. We considered that a patient adherence was not fulfilled when the mean pill count was < 90% or when any plasma drug level was lower than that expected. RESULTS: Of 143 available patients, 41.2% were non-adherent. According to the univariate analysis, non-adherent patients were more likely to be younger, female, under a methadone maintenance scheme, under psychiatric treatment, to have depression (according to the Beck Depression Inventory), to have adverse antiretroviral effects and to have a previous history of voluntary withdrawal of the treatment. Men who had sex with other men were significantly more adherent. In the multivariate analysis, female sex [OR 2.6 (1.04-6.65)], to be under a methadone program [OR 9.43 (1.01-88)], to have adverse drug effects [OR 2.63 (1.09-6.33)] and to have a previous history of voluntary withdrawal [OR 2.63 (1.09-6.36)] were independent risk factors for non-adherence. CONCLUSIONS: Adherence to antiretroviral therapy was 58.8%, similar to that seen in other chronic diseases. To be under a methadone maintenance program and having an active drug addiction was related with non-adherence. Women with worst adherence levels had frequently psychiatric comorbidity and more adverse drug effects.