Validation of a simplified medication adherence questionnaire in a large cohort of HIV-infected patients: the GEEMA Study

Abstract

To assess the effectiveness of the simplified medication adherence questionnaire (SMAQ) in identifying non-adherent patients. Prospective observational study of adherence. The six-item SMAQ was developed. The following aspects were evaluated: (i) criterion validity, comparison with electronic adherence monitoring; (ii) construct validity, association between adherence, as defined by the SMAQ, and virological outcomes; and (iii) reliability, internal consistency and reproducibility. A group of 3004 unselected HIV patients who had initiated nelfinavir therapy combined with other antiretroviral drugs [21% naive, 15% protease inhibitor (PI)-naive, 64% PI-experienced] between January 1998 and December 1999 were enrolled in 69 hospitals in Spain. The SMAQ was administered at months 3, 6 and 12. The SMAQ showed 72% sensitivity, 91% specificity and a likelihood ratio of 7.94 to identified non-adherent patients, compared with the medication-event monitoring system (40 patients evaluated). At month 12, 1797 patients were evaluated, of whom 32.3% were defined as non-adherent; viral load 5 log10/ml, CD4 cell count 6 The SMAQ appears to be an adequate instrument with which to assess adherence in HIV-infected patients, and may be applied in most clinical settings.