The use of haemoglobin and body mass index as predictors of mortality in HIV patients newly initiated on highly active antiretroviral therapy
Date
2013
Authors
Tesfay, Abraham Rezene
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Background:
More than 33 million people are estimated to be living with HIV worldwide. Sub-Saharan
Africa bears a disproportionate share of the global HIV burden. An estimated 15 million
people living with HIV in low and middle income countries were in need of (HAART) in
December 2009. HAART services require advanced laboratory technologies to monitor
disease progression and therapeutic response, which are scarce in developing countries.
Several simple and widely available markers have been proposed for use in low income
countries including total lymphocyte count (TLC), haemoglobin and body mass index.
Methodology:
This study is a secondary data analysis of prospectively collected cohort data from HIV
positive adults. The study measured the effect of exposure variables of haemoglobin (Hb) and
body mass index (BMI). All cause mortality was the outcome of interest. Crude estimates of
mortality were made with Kaplan-Meier mortality curves. Cox proportional hazards models
were used to estimate adjusted hazard ratios. Exposure status was considered at initiation
period. Outcomes were measured from two weeks post initiation of treatment to a maximum
of two years of follow-up period. A composite score was developed to estimate the overall
risk of mortality.
Results:
A total of 11,884 patients who satisfied the inclusion criteria were included in the analysis. A
total of 1,305 deaths were observed during the follow-up period, representing 10.2% of the
cohort at baseline. Most of the deaths were observed during the first four months of follow-up
period. Patients with moderated to severe anaemia experienced 2.6 (HR = 2.6, 95% CI 1.8 -
3.6) times greater hazard of mortality adjusted for possible confounders. Patients with very
iv
low BMI experienced twice (HR=2.0, 95% CI 1.6, -2.5) greater hazard of mortality adjusted
for a list of predictors. Race, age at initiation, employment status, smoking, alcohol
consumption, baseline TB and baseline WHO stage did not show significant effect in the
multivariate cox regression model.
A composite score was developed to estimate the overall risk of mortality in patients based
on measurements of baseline BMI and haemoglobin. Cox regression model adjusted for CD4
cell count shows high risk patients experienced 4.7 (HR = 4.7, 95% CI 2.9 – 7.6) times
greater hazard of mortality compared to patients in the low risk group. Patients in the medium
risk group experienced 3.4 (HR = 2.6, 95% CI 2.6 – 4.4) times greater hazard of mortality as
opposed to patients in the low risk group.
Conclusion:
Haemoglobin and body mass index provide excellent prognostic information independent of
CD4 cell count in HIV positive patients newly initiated on HAART. They can be used to
reliably predict mortality. Combining measurements of haemoglobin and BMI through
composite scoring improves their predictive ability. They can have good clinical application
in rural and remote facilities to screen patients for clinical and diagnostic services.
Description
A Research Report Submitted to the School of Public Health, University of the
Witwatersrand, Johannesburg, in Partial Fulfilment of the Requirements for the Degree of
Master of Science in Medicine in the Field of Epidemiology and Biostatistics:
March 25, 2013