Most HIV/HBV co-infected patients in Europe have detectable HBV viral load

Only a third of HIV-positive patients co-infected with chronic hepatitis B virus in Europe have an undetectable hepatitis B viral load, according to a EuroSIDA study presented to the 12^th European AIDS Conference in Cologne.

This low rate of undetectable hepatitis B viral load was despite the fact that approximately two-thirds of patients were taking antiretroviral therapy that included drugs with activity against hepatitis B.

HIV and hepatitis B share similar modes of transmission and a significant proportion of patients are co-infected with these viruses.

Factors associated with the progression of liver disease in co-infected patients include hepatitis B genotype and hepatitis B viral load.

Therefore investigators from the EuroSIDA cohort study analysed stored blood samples and patient notes to determine the epidemiological and clinical characteristics of chronic hepatitis B infection in these co-infected patients.

Of the 16,500 patients in the cohort, 7% (1200) had chronic hepatitis B infection and of these 484 had stored samples that were included in the study. These were obtained between 1994 and 2006.

Most of the patients were men (84%), Caucasian (85%) and gay (51%).

It was possible to determine hepatitis B genotype in 167 patients, the most common being genotype A. This genotype was found significantly more often in gay men than injecting drug users (p

An undetectable hepatitis B viral load (below 357 copies iu/ml) was present in 34% of patients. Worryingly, 20% of patients had a viral load above 10,000,000 copies iu/ml, which is known to significantly increase the risk factor of cirrhosis and liver cancer.

Antiretroviral therapy was being taken by 90% of patients. A third of these individuals were taking a combination of drugs that had no activity against hepatitis B.

A third of patients taking 3TC had an undetectable hepatitis B viral load compared to 45% of those taking a combination including tenofovir (with or without 3TC or FTC). However, this difference was not significant. The investigators also noted that none of the patients taking this drug had a hepatitis B viral load above 10,000,000 copies iu/ml.

Statistical analysis showed that each doubling of baseline CD4 cell count significantly reduced the chances of having an undetectable hepatitis B viral load (p = 0.013). A total of 27% of patients were also co-infected with hepatitis C virus, and the investigators found that these patients were also more likely to have an undetectable hepatitis B viral load (p = 0.025).