Validation of a simplified medication adherence questionnaire in a large cohort of HIV-infected patients: the GEEMA Study.
OBJECTIVE
To assess the effectiveness of the simplified medication adherence questionnaire (SMAQ) in identifying non-adherent patients.


METHODS
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.


METHODS
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.


RESULTS
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 < 500 copies/ml found in 68.3% of the adherent, and 46% of the non-adherent patients. A logistic regression analysis of PI-naive patients was performed, including age, sex, baseline viral load > 5 log10/ml, CD4 cell count < 200 x 10(6)/l, and non-adherence as independent variables. Non-adherence was the only significant risk factor in failing to achieve virological suppression. Cronbach's alpha internal consistency coefficient was 0.75, and overall inter-observer agreement was 88.2%.


CONCLUSIONS
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.
Knobel
Hernando
H
Department of Internal Medicine-Infectious Diseases, Hospital del Mar, Paseo Marítimo 25-29, 08003 Barcelona, Spain. hknobel@imas.imem.es
Alonso
Jordi
J
Casado
José L
JL
Collazos
Julio
J
González
Juan
J
Ruiz
Isabel
I
Kindelan
José M
JM
Carmona
Alexia
A
Juega
Javier
J
Ocampo
Antonio
A
D000328:Adult; D018791:CD4 Lymphocyte Count; D015331:Cohort Studies; D005260:Female; D015658:HIV Infections / Q000188:drug therapy / Q000276:immunology / Q000523:psychology* / Q000821:virology; D017320:HIV Protease Inhibitors / Q000627:therapeutic use; D006801:Humans; D008297:Male; D010349:Patient Compliance / Q000706:statistics & numerical data*; D011446:Prospective Studies; D013030:Spain; D011795:Surveys and Questionnaires / Q000592:standards*; D016896:Treatment Outcome
D017320:HIV Protease Inhibitors