Adherence Measure Methods to Antiretroviral Therapy in HIV-Infected Patients in South Africa Público

Abstract

Background

Previous studies have shown that highly active antiretroviral therapy (HAART) has a positive impact in reducing the HIV-related death. Adherence to therapy is a strong predictor of virologic failure (VF) among patients. A few methods such as pill count have been utilized to monitor the adherence. However, in resource-limited settings such as in South Africa, more trials and analyses should be done due to inadequate research.

Objective

In the retrospective case-control study we conducted, we sought several adherence assessment methods including pill count, medication possession ratio (MPR), adherence score and aimed at identifying risk factors that may predict VF at 6 months.

Methods

Several smooth splines corresponding to each of these adherence assessment methods were fit in a logistic model to evaluate the association between the estimated probability and those predictors. We also used different combinations of those adherence assessment methods as new factors to predict VF. Additionally, we split the pharmacy refill period into several intervals according to each patient's pharmacy refill dates to monitor the habits of the patients' follow-to-prescription. We adopted a Generalized Estimating Equation (GEE) approach to investigate the relationship between the virologic failure and the pick-up times as well as pills left at each visit.

Results

458 patients participated in antiretroviral therapy from October 2010 to June 2012. Of these, 158 (34.50%) had virologic failure (cases) and 300 (65.50%) did not (controls). The mean adherence score is 98.15% in case group and 94.80% in control group. Adherence score may be not the best in retrospective study. ROC analysis shows the combination of pharmacy refill ratio plus self-reported question can be a strong tool to predict VF. The number of visits have strong association with refill pattern (p<0.0001) using Generalized Estimating Equation (GEE) approach.

Table of Contents

Table of Contents

CHAPTER 1: INTRODUCTION & BACKGROUND.. 1

HIV/AIDS and Antiretroviral Therapy (ART). 1

Marconi Study (Risk Factors of Virological Failure Study). 2

Adherence Measure Methods. 3

Access to ART in Resource-Limited Settings. 4

CHAPTER 2: METHODOLOGY. 6

Study Question. 6

Study Site. 6

Data Collection and Cleaning. 6

Adherence Measurement. 7

Model Specification. 9

Receiver Operating Characteristic (ROC). 10

Generalized Estimating Equation (GEE). 11

CHAPTER 3: RESULTS. 13

Descriptive Analysis. 13

"Drug Hierarchy". 13

Parametric Splines. 15

ROC Analysis. 16

Refill Gap Analysis. 18

Repeated Measurements. 18

Generalized Linear Models. 18

CHAPTER 4: CONLUSION & DISCUSSION.. 20

CHAPTER 5: TABLES & FIGURES. 23

References. 35

About this Master's Thesis

Rights statement

• Permission granted by the author to include this thesis or dissertation in this repository. All rights reserved by the author. Please contact the author for information regarding the reproduction and use of this thesis or dissertation.

School	Rollins School of Public Health
Department	Biostatistics and Bioinformatics
Subfield / Discipline	Biostatistics - MPH & MSPH
Degree	MSPH
Submission	Master's Thesis
Language	English
Research Field	Biology, Biostatistics Statistics Health Sciences, Epidemiology
Palavra-chave	GEE Logistic Regression ART Adherence RFVF ROC
Committee Chair / Thesis Advisor	Johnson, Brent, Emory University
Committee Members	Hanfelt, John, Emory University
Partnering Agencies	Emory University schools, faculty or affiliated programs Hospital or other health care provider

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