Modeling CD4 + Cell Counts of HIV-Positive Patients Following Antiretroviral Therapy (ART): A Case of Yekatit 12 Hospital, Addis Ababa
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Date
2016-06
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Addis Abeba university
Abstract
HIV infection leads to severe depletion of CD4+ counts with subsequent reduced levels of
circulating CD4+ lymphocytes in the peripheral blood. CD4+ counts are the primary laboratory
markers used to track the progression of HIV to AIDS. It is the strongest predictor for risk of death
and AIDS (DHHS, 2011) at the time of initiating therapy and used to decide when to start ART
treatment. The main objective of this study was to model the progression of CD4+ cell counts of
HIV- positive patients following ART. A longitudinal data was obtained from ART case unit of
HIV positive patients in Yekatit 12 Hospital who were following ART from September 10, 2009
to September 9, 2012 G.C and followed until January 9, 2016 G.C, Addis Ababa. The data was
extracted from SMART CARE of patients chart and patients with at least three times of
measurements and those in first line ART regimens were included. The linear mixed model
analysis was applied taking the correlation between CD4+ counts of patients into account. We
included 217 patients of whom 141 (65%) were females and only 51.61% of patients were followed
until the last follow up time inducing 48.39% missingness. The results from the linear mixed model
with AR(1) covariance structure showed that baseline CD4+ count, WHO clinical stage, time and
the interaction effects of sex, Age, baseline CD4+ count and regimen class with time were
statistically significant factors for the progression of CD4+ count at a square root level over time.
Results from the full likelihood and multiple imputation approaches were found to be almost
identical for covariates that were significant. The mean CD4+ count showed an increasing progress
over time after patients were initiated on ART. We recommend that patients should be initiated to
ART regimens at an early WHO clinical stages, at a higher CD4+ count and ART regimens should
be taken continuously to increase the progress of CD4+ count.
KEY WORDS: ART, CD4+, Linear Mixed Model, Longitudinal Data, Missing Data, AR(1), ML,
MI, MAR
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Keywords
Art, Cd4+, Linear Mixed Model, Longitudinal Data, Missing Data, Ar(1), Ml, Ml, Ma