Younger individuals and women who use injectable drugs are at increased risk for HIV and hepatitis C virus (HCV) infection, according to results of a systematic review and meta-analysis published in The Lancet Gastroenterology and Hepatology.
Researchers at Bristol Medical School in the United Kingdom searched publication databases through December 2022 for global incidence rates (IRs) on HIV and HCV infection among individuals who use injectable drugs.
Among 195 countries, this study included estimates of HIV and HCV incidence captured from 27 (14%) and 24 (12%), respectively. Estimates of both HIV and HCV incidence were captured from 20 (10%) countries. Data were collected between 1987 and 2021 for HIV incidence and between 1992 and 2021 for HCV incidence.
A total of 3246 incident HIV diagnoses were reported within a follow-up of period of 180,857.2 person-years (py), for a pooled incidence rate (IR) of 1.7 per 100 py (95% CI, 1.3-2.3; I2, 98.4%).
The IR of HIV associated with injection drug use differed significantly by World Health Organization (WHO)-defined region (P <.0001) and World Bank income classification (P <.0001). Significant differences in HIV incidence were also observed on the basis of study duration (P <.0001), follow-up duration (P <.0001), HIV antibody prevalence (P <.0001), sampling strategy (P =.015), enrollment strategy (P =.015), incidence estimation strategy (P =.046), and study population age (P =.036).
For WHO-defined regions, the highest HIV incidence was observed in the Eastern Mediterranean (IR, 4.1 per 100 py; I2, 90.6%) and the lowest was observed in mixed regions (IR, 0.5 per 100 py). Stratified by World Bank income classification, HIV incidence ranged from 3.2 per 100 py (I2, 98.5%) in low- and middle-income countries (LMICs) to 0.9 per 100 py (I2, 93.9%) in high-income countries.
A total of 4233 incident HCV diagnoses were reported within a follow-up period of 44,841.2 py, indicating a pooled IR of 12.1 per 100 py (95% CI, 10.0-14.6; I2, 97.2%).
Significant associations with HCV incidence included study sampling strategy (P <.0001), enrollment strategy (P =.012), follow-up duration (P <.0001), duration of injection drug use (P <.0001), and study population age (P =.0003).
For WHO-defined regions, the highest injection drug use-associated HCV incidence was observed in the Eastern Mediterranean (IR, 16.1 per 100 py; I2, 96.9%) and the lowest was observed in Southeastern Asia (IR, 6.4 per 100 py; I2, 96.9%). Stratified by World Bank income classification, HCV incidence was highest in LMICs (IR, 12.6 per 100 py; I2, 95.0%) and lowest in high-income countries (IR, 12.1 per 100 py; I2, 97.4%).
The overall incidence rate ratio (IRR) of HCV infection compared with HIV infection was 17.4 (95% CI, 9.0-33.8; I2, 96.9%).
Stratified by age and gender, younger (age, ≤25 years) vs older individuals were at increased risk for both HIV infection (relative risk [RR], 1.5; 95% CI, 1.2-1.8; I2, 66.9%) and HCV infection (RR, 1.5; 95% CI, 1.3-1.8; I2, 70.6%). In addition, women vs men were at increased risk for both HIV infection (RR, 1.4; 95% CI, 1.1-1.6; I2, 55.3%) and HCV infection (RR, 1.2; 95% CI, 1.1-1.3; I2, 43.3%).
Study limitations include significant heterogeneity and the fact that most estimates of HIV and HCV incidence were sourced from Europe, America, and West Pacific WHO-defined regions.
According to the researchers, “Our review also illustrates the scarcity of HIV and HCV incidence data among PWID [people who inject drugs] globally, which were available in only 14% and 12% of countries, respectively.”
Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
Artenie A, Stone J, Fraser H, et al. Incidence of HIV and hepatitis C virus among people who inject drugs, and associations with age and sex or gender: a global systematic review and meta-analysis. Lancet Gastroenterol Hepatol. Published online March 27, 2023. doi:10.1016/S2468-1253(23)00018-3