People who inject drugs (PWID) are at a greater risk of hepatitis B virus (HBV), but that risk largely depends on which country they live in.

A team, led by Anjalee Syangbo, Population Health Sciences, University of Bristol, identified the associations between country-level chronic HBV prevalence in people who inject drugs with national indicators of development and prevalence of HIV and HCV.

The Risk

It is well-established that people who inject drugs are at a greater risk of contracting HBV compared to the general population. However, the risk often depends on different societal factors based on the country.

“While previous research has highlighted that country-level income is associated with HBV prevalence in the general population, there has been limited research into country-level associations with HBV prevalence among PWID,” the authors wrote. “Our hypothesis was that countries with higher levels of inequality and poverty would have higher prevalence of HBV among PWID when controlling for general population HBV prevalence, a relationship that would be acting through the unequal distribution of vaccinations and harm-reduction measures.”

The Prevalence

A recent estimate had the global prevalence of HBV among people who inject drugs to be 9.1%. In addition, approximately 22.6% of people who inject drugs have evidence of past infections.

In the study, the investigators used global systematic review data on chronic HBV prevalence among individuals who inject drugs and country—level sociodemographic characteristics from different online databases.

The team used linear regression models testing for associations with country-level characteristics to estimate HBV prevalence with the national random-effects meta-analysis.

The Data

Overall, there was data for 131,710 individuals who inject drugs from 304 estimates in 55 countries. The pooled prevalence of HBV in this specific patient population in the countries analyzed was 4.5% (95% CI, 3.9-5.1). However, the analysis showed the highest regional pooled prevalence was in countries in East and Southeast Asian (17.6%; 95% CI, 13.3-22.3).

The prevalence of HBV among people who inject drugs was 1.7% (95% CI, 1.4-2.1) in Western Europe, the lowest among all of the regions analyzed.

After using the multivariable models, the investigators found no evidence of positive associations between HBV prevalence in the general population and among people who inject drugs, and evidence of HIV and HCV prevalence in this group being associated with HBV prevalence in people who inject drugs (multivariable coefficients, 0.03; 95% CI, 0.01–0.04; P <0.001, and 0.01; 95% CI, 0.00–0.03; P = 0.01, respectively).

“HBV prevalence among PWID was associated with HIV and HCV prevalence among PWID and background HBV prevalence in the general population, highlighting the need for improving harm reduction in PWID and implementation of HBV vaccination, especially where HBV is endemic,” the authors wrote.

The study, “Associations between the prevalence of chronic hepatitis B among people who inject drugs and country-level characteristics: An ecological analysis,” was published online in Drug and Alcohol Review.