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The interplay between CD 4 cell count, viral load suppression and duration of antiretroviral therapy on mortality in a resource‐limited setting
Author(s) -
Brennan Alana T.,
Maskew Mhairi,
Sanne Ian,
Fox Matthew P.
Publication year - 2013
Publication title -
tropical medicine and international health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.056
H-Index - 114
eISSN - 1365-3156
pISSN - 1360-2276
DOI - 10.1111/tmi.12079
Subject(s) - viral load , medicine , antiretroviral therapy , cohort , human immunodeficiency virus (hiv) , survival analysis , immunology , demography , sociology
Objective To examine the interaction between CD 4 cell count, viral load suppression and duration of antiretroviral therapy ( ART ) on mortality. Methods Cohort analysis of HIV ‐infected patients initiating ART between April 2004 and June 2011 at a large public sector clinic in Johannesburg, S outh A frica. A log‐linear model with Poisson distribution was used to estimate risk of death as a function of the interaction between current CD 4 count, current viral load suppression and duration on ART in 12‐month intervals. We calculated predicted mortality using estimated coefficients within combinations of predictors. Results Amongst 14 932 ART patients, 1985 (13.3%) died. Current CD 4 was the strongest predictor of death (<50 vs . ≥550 cells/mm 3 – RR : 46.3; 95% CI : 26.8–80), while unsuppressed current viral load vs . suppressed ( RR : 1.8; 95% CI : 1.5–2.1) and short duration of ART (0–11.9 vs . 66–71.9 months RR : 1.7; 95% CI : 1.2–2.3) also predicted death. Our interaction model showed that mortality was highest in the first 12 months on treatment across all CD 4 and viral load strata. As current CD 4 and duration on ART increased and viral load suppression occurred, mortality dropped. CD 4 count was the strongest predictor of death. The relative effect of current CD 4 count varied strongly by viral load and duration of ART (from 1.3 to 55). Lack of suppression increased the risk of mortality upwards of six‐fold depending on time on ART and current CD 4. Conclusions Our findings show that while CD 4 count is the strongest predictor of death, the effect is modified by viral load and the duration of ART . Assessment of risk should take into account all three factors.