Estimation of Quality Adjusted Life Years (QALYs) for HIV Patients on Art in Kenya Using Proxy Utility Function

Abstract

Aims: This study seeks to estimate QALYs for HIV/AIDS patients on ART in Kenya to quantitatively evaluate the health impact of ART treatment on patients. QALYs values are important as they form a                 basis for evidence based decision making and policy formulation in the country with regards to HIV/               AIDS. Study Design: The study involved secondary data obtained from a retrospective follow up study on hospital records of HIV/AIDS patients enrolled for ART from 2005 to 2017. Place and Duration of Study: Jomo Kenyatta University of Agriculture and Technology, between January 2019-April 2022. Methodology: The study involved a retrospective study of 3000 patients on ART in Kenya from the period of 2005-2017. All the patient records are identified using random patient id ensuring the privacy and anonymity of patients. The inclusion criteria is patients who had complete information on the covariates used in the model during follow up. The joint modelling of the longitudinal and survival data of each patient was applied and the results applied to proxy utility function to estimate the QALYs for patients on ART. To get the average QALYs gained by all patients, we aggregate the total QALYs from each patient. R. Software version 4.0.2 was used in the analysis. Results: Sex, age, Marital Status and weight are significant predictors of survival of HIV Patients on ART in Kenya. Being on ART therapy resulted in a gain of 9.688313 QALYs for HIV/AIDS patients. The association parameter estimate is-0.0345 implying that increase in the values of CD4 count results in a decrease in the hazard of death for HIV patients on ART therapy. Conclusion: The proxy utility function methodology is appropriate for the calculation of QALYs values for HIV patients on ART. It has the advantage of allowing utilities of each patient to vary and are calculated at every time point. Since ART results in the improvement in QALYs of patients, efforts should be directed towards ensuring patients who are enrolled for the therapy continue with it for sustained health and non health benefits.