XVIII International AIDS Conference


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Defining the best tool to assess adherence to antiretroviral therapy using sensitivity and specificity analysis of simple questions and pharmacy records

C. Pereira de Souza1,2, L.A. Alves de Lima1, G. Santoro Lopes1

1Federal University of Rio de Janeiro, Preventive Medicine - Infectious Diseases Service, Rio de Janeiro, Brazil, 2Hospital Escola São Francisco de Assis - Federal University of Rio de Janeiro, AIDS Care Unit, Rio de Janeiro, Brazil

Background: Adherence is essential for a successful antiretroviral therapy. Incomplete suppression of viral replication has been used as marker of poor adherence. Self-report questionnaires and pharmacy records are considered strong predictors of suboptimal adherence, but to establish which questions should be asked to obtain maximal sensitivity and specificity, is not well established.
Methods: A self-reported questionnaire with four simple questions, including a visual analogue grades scale attributed to self adherence, from zero to ten, was applied a single time among HIV infected individuals on ART. Additionally, pharmacy records were computed from 2 months before to 2 months after the interviews were performed. The answers and registers were confronted with plasma viral load measurements closest to the date of interview. Incomplete suppression of viral replication was considered evidence of poor adherence. ROC curves were constructed, using the parameters found to be statistically associated with detectable viral load, to determine which combination of them would result in maximal AUC (area under curve). Statistical analysis was done using SPSS 13.0.
Results: 441 patients, 35.2% female, were interviewed. 356 (80.4%) patients had undetectable viral load. Self attributed grades smaller than 9 in the past month, multiple delays in drug intake and pharmacy records showing at least one interval between refills greater than 40 days were independently associated with detectable viral load. Maximal accuracy for non adherence was obtained when at least two of those three parameters are present.
Conclusions: Maximal accuracy for suboptimal adherence can be obtained by using a score based on a simple set of questions and pharmacy records.

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