Medication Adherence Is More Critical Than Initial CD4 Count in Predicting HIV Survival

Adherence to an antiretroviral regimen is more important than the CD4 cell count at which antiretroviral therapy is begun in determining the survival with HIV, according to a report in the November 18th Annals of Internal Medicine.

Several studies have suggested that delaying the initiation of highly active antiretroviral therapy (HAART) after the CD4 cell count falls below 350 cells/microliter is unsafe, the authors explain, but the optimal time to initiate HAART remains uncertain.

Dr. Julio S.G. Montaner and colleagues from University of British Columbia, Vancouver, British Columbia, Canada evaluated the effect of baseline CD4 cell count and adherence on survival rates after the initiation of HAART in 1422 HIV-infected patients.

Among patients with a baseline CD4 cell count of at least 200 cells/microliter, the crude mortality rate was twice as high among those who were less than 75% adherent (15.2%) than among those who were at least 75% adherent (7.1%), the authors report.

Mortality rates associated with nonadherence were increased 2.5-fold even among patients whose baseline CD4 cell counts were 350 cells/microliter or greater, the results indicate.

In Kaplan-Meier survival analyses, patients with baseline CD4 cell counts of at least 200 cells/microliter fared as well as patients with higher baseline CD4 cell counts as long as they were at least 75% adherent.

Results were similar when 95% adherence was used to stratify the patients, the report indicates, and censoring accidental causes of death from the analysis did not influence the conclusions.

"These data suggest that patient nonadherence, instead of when antiretroviral therapy is initiated before a CD4+ cell count of 200 cells/microliter, may be the strongest determinant of patient survival," the authors conclude. "These results should be useful for patients weighing the difficult decision about the optimal time to initiate HAART and for the ongoing development of therapeutic guidelines."

11/21/03

Ann Intern Med 2003;139:810-816.