By Liz Highleyman

While many HIV positive people have been exposed to hepatitis B virus (HBV), a majority do not develop chronic infection, and the natural history HIV-HBV coinfection has not been extensively studied.

In a poster presentation at the XVII International AIDS Conference taking place this week in Mexico City, researchers from St. Luke's-Roosevelt Hospital in New York City reported on a study looking at predictors of loss of hepatitis B surface antigen (HBsAg) in HIV-HBV coinfected individuals.

As background, the investigators noted that coinfection is associated with increased morbidity and mortality, but the factors that influence treatment outcomes in this population are not well defined.

In this analysis, they retrospectively reviewed the medical records of 5681 patients followed at St. Luke's-Roosevelt Hospital HIV clinic from January 1999 to May 2007. Of these, they identified 355 patients coinfected with HBV on the basis of positive HBsAg.

Clinical and laboratory parameters including patient demographics, HIV viral load, CD4 cell count, alanine aminotransferase (ALT) level, and duration of antiretroviral and anti-HBV therapy were analyzed to determine factors associated with HBsAg loss.

During the follow-up period, 283 coinfected patients (79.7%) received antiretroviral drugs with activity against HBV, including lamivudine (Epivir-HBV), tenofovir (Viread, also in the Truvada and Atripla combination pills), adefovir (Hepsera), or entecavir (Baraclude).

Results

• In the group that received agents active against HBV, 29 of 283 (10.3%) lost HBsAg, compared with 7 of 72 (9.7%) who did not receive any anti-HBV antiretrovirals (not a statistically significant difference).

• In a univariate analysis, baseline CD4 count, CD4 count at the end of follow-up, and CD4 cell gain were associated with loss of HBsAg (P = 0.027, 0.013, 0.053, respectively).

• Using Cox regression analysis, the following variables were associated with HBsAg loss:

• Normal ALT (OR 0.165; P = 0.010);
• Baseline CD4 count > 500 (OR 25.468; P = 0.004);
• CD4 cell gain of 71-150 cells/mm3 (OR 7.603; P = 0.047).

In this cohort, the investigators concluded, use of anti-HBV therapy was not associated with loss of HBSAg in HIV-HBV coinfected patients.

However, they continued, "Positive correlations were observed with CD4 count at baseline, as well as amount of CD4 increase. High CD4 counts at the time of HBV infection and immune restoration through [antiretroviral therapy] are the most important predictors in successful treatment of HBV in HIV infected patients."

8/08/08

Reference
JH Kim, G Psevdos, J Park, and others. Predictors of loss of hepatitis B surface antigen in HIV and hepatitis B virus co-infected patients. XVII International AIDS Conference. Mexico City. August 3-8, 2008. Abstract WEPDB207.