Study of the Validity of a Questionnaire to Assess the Adherence to Therapy in Patients Infected by HIV

Abstract

Purpose: The purpose of our study was to examine the validity of a questionnaire to detect nonadherence in HIV-infected patients under antiretroviral treatment. Method: This was a cross-sectional study to validate a diagnostic test. Participants consisting of 242 HIV-infected patients were elected by consecutive sampling in a hospital in Madrid. The validation standard was the pharmacy dispensing records with the cut point being 80% and 90% of delivered drugs. Sensitivity (S), specificity (SP), positive predictive value (PPV), and positive likelihood ratio (PLR) of the questionnaire were estimated. Results: The mean age of the participants was 36.2 years old (SE 0.42), 55% were men, and 68.2% had used parenteral drugs. Eighty-three patients (34.3%) did not reach 80% of the prescribed dose and 129 patients (53.3%) did not reach 90%. In the 80% group, S was 25.3% (95% CI, 16.7%-36.2%),SP was 86.2% (95% CI, 79.6%-90.9%), PPV was 48.9% (95% CI, 33.5%-64.3%), and the PLR was 1.83 (95% CI, 1.07-3.13). In the 90% group, the S was 19.4% (95% CI, 13.4%-27.4%), SP was 84.0% (95% CI, 75.7%-90.0%), PPV was 58.1% (95% CI, 42.4%-72.6%), and PLR was 1.22 (95% CI, 0.70-2.12). Conclusion: The proposed questionnaire is not a reliable diagnostic method to detect nonadherence. It should only be incorporated into the daily clinical practice along with other methods of nonadherence measurement.

Keywords:

• adherence
• compliance
• HIV infection
• treatment
• sensitivity
• specificity