THE IMPACT OF THE HEPATITIS C VIRUS (HCV) ON CD4 RESPONSE POST INITIATION OF HIGHLY ACTIVE ANTIRETROVIRAL THERAPY (HAART) AMONG A POPULATION-BASED HIV COHORT

P Braitstein, JJ Asselin, V Montessori, E Wood, B Yip, K Chan, KJP Craib, MV O'Shaughnessy, MT Schechter, JSG Montaner, RS Hogg
BC Centre for Excellence in HIV/AIDS, Vancouver, British Columbia

Objective: To characterize the impact of HCV on CD4 response to initiation of HAART in a population-based HIV/AIDS treatment cohort.
Methods: The HIV/AIDS Treatment Program distributes, at no cost, all antiretrovirals in British Columbia, Canada. Eligible individuals were those whose first ever antiretroviral therapy was two NRTI's plus a PI or a NNRTI, and who had documented HCV serology. All available CD4 responses post initiation of HAART were examined. Adherence was measured through prescription refills. Statistical analyses used non-parametric methods and linear regression; mixed effect models were used to determine factors independently associated with CD4 increases over time.
Results: Of the 1416 ART-naïve individuals who initiated triple-combination therapy, 552 (39%) had recorded HCV-Ab test results, of whom 235 (43%) were HCV-antibody positive, and 317 (57%) were HCV-antibody negative. There were significant differences in median baseline values (HCV-negative: 240 cells vs HCV-positive: 280, p<0.001). Using linear regression, a statistically significant increase in CD4's over time was found for HCV-negatives (p=0.008), but not for HCV-positives (p=0.122). These trends were maintained even among individuals who were ³95% adherent (HCV-negative p=0.004; HCV-positive p=0.162). Mixed effect modeling found that factors independently predicting CD4 increase were HCV-serostatus (p<0.001), time (p<0.001), being ³95% adherent (p<0.001), and baseline CD4 (p<0.001). Non-significant variables tested were gender, age, and baseline viral load. After adjustment for potential confounders, HCV-negative individuals gained an average of 33.5 CD4 cells per day, whereas HCV-positive individuals lost an average of 5.3 cells per day (p<0.001).
Conclusion: There appears to be an altered CD4 response over time among HCV-positive individuals following initiation of HAART, even after controlling for adherence. The clinical significance of these differences remains to be determined.

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