Abstract
Background: Measuring progress towards the 2030 WHO incidence target for hepatitis C virus (HCV) elimination among people who inject drugs (PWID; ≤2/100 person-years (py)) has been challenging due to limited data. We estimated HCV incidence among PWID for the pre- and post-2015 periods, progress towards the 2030 target, and the number of new annual HCV infections attributed to injecting drug use post-2015.
Methods: Four sequential steps were taken to estimate country-specific HCV incidence. First, we estimated HCV incidence from HCV antibody prevalence by duration of injecting using force-of-infection (FOI) modelling. Second, using Bayesian random-effects meta-analysis, we pooled FOI-derived with any direct HCV incidence estimates from a published global systematic review, by country. Third, for countries with no FOI-derived or direct HCV incidence data, we applied estimates from a published multi-country dynamic mathematical model. Fourth, for countries with no estimate of HCV incidence based on the prior methods but with data on overall (i.e., not stratified by duration of injecting) HCV antibody prevalence, we used a regression model to predict incidence based on prevalence and average duration of injecting. WHO regional and global HCV incidence, rate ratios for the post- vs pre-2015 periods, and relative decline needed to achieve the 2030 WHO target were derived and weighted by the country-specific number of at-risk (i.e., RNA-negative) PWID, provided data from ≥5 countries were available within a WHO region. The most recent incidence estimates included were from 2021, so the post-2015 period is defined as 2015–2021. New annual HCV infections attributed to injecting drug use were estimated by multiplying country-specific HCV incidence for 2015-2021 with the number of RNA-negative PWID; for countries with no HCV incidence data but with evidence of an existing PWID population, these were imputed using the corresponding WHO regional incidence.
Findings: For the pre-2015 period, 146 HCV incidence estimates from 81 countries were included: 52 (36%), 61 (42%), and 33 (23%) were direct, FOI-derived, and regression-based, respectively. For 2015-2021, 114 estimates from 97 countries were included: 20 (18%), 18 (16%), 68 (60%) and 8 (7%) were direct, FOI-derived, dynamic model-derived, and regression-based, respectively. Globally, pooled HCV incidence was 13.9/100py (95% uncertainty interval (UI): 11.9–16.4) pre-2015 and 8.6/100py (95%UI: 7.1–10.7) over 2015-2021. Based on a subset of countries with data for both time periods, incidence was lower in the Western Pacific, European and Eastern Mediterranean regions over 2015-2021 vs pre-2015, but no difference was observed in the American region. Insufficient data prevented comparisons over time for the African and South-East Asian regions and globally. Based on 2015-2021 HCV incidence, the global decline needed to meet the 2030 WHO target is 76.7% (95%UI: 71.8%-81.3%), while the global number of new annual HCV infections attributed to injecting drug use is 833,760 (95%UI: 493,716–1,544,395).
Interpretation: A substantial increase in HCV prevention is needed globally to achieve the WHO HCV elimination target on incidence among PWID.
Methods: Four sequential steps were taken to estimate country-specific HCV incidence. First, we estimated HCV incidence from HCV antibody prevalence by duration of injecting using force-of-infection (FOI) modelling. Second, using Bayesian random-effects meta-analysis, we pooled FOI-derived with any direct HCV incidence estimates from a published global systematic review, by country. Third, for countries with no FOI-derived or direct HCV incidence data, we applied estimates from a published multi-country dynamic mathematical model. Fourth, for countries with no estimate of HCV incidence based on the prior methods but with data on overall (i.e., not stratified by duration of injecting) HCV antibody prevalence, we used a regression model to predict incidence based on prevalence and average duration of injecting. WHO regional and global HCV incidence, rate ratios for the post- vs pre-2015 periods, and relative decline needed to achieve the 2030 WHO target were derived and weighted by the country-specific number of at-risk (i.e., RNA-negative) PWID, provided data from ≥5 countries were available within a WHO region. The most recent incidence estimates included were from 2021, so the post-2015 period is defined as 2015–2021. New annual HCV infections attributed to injecting drug use were estimated by multiplying country-specific HCV incidence for 2015-2021 with the number of RNA-negative PWID; for countries with no HCV incidence data but with evidence of an existing PWID population, these were imputed using the corresponding WHO regional incidence.
Findings: For the pre-2015 period, 146 HCV incidence estimates from 81 countries were included: 52 (36%), 61 (42%), and 33 (23%) were direct, FOI-derived, and regression-based, respectively. For 2015-2021, 114 estimates from 97 countries were included: 20 (18%), 18 (16%), 68 (60%) and 8 (7%) were direct, FOI-derived, dynamic model-derived, and regression-based, respectively. Globally, pooled HCV incidence was 13.9/100py (95% uncertainty interval (UI): 11.9–16.4) pre-2015 and 8.6/100py (95%UI: 7.1–10.7) over 2015-2021. Based on a subset of countries with data for both time periods, incidence was lower in the Western Pacific, European and Eastern Mediterranean regions over 2015-2021 vs pre-2015, but no difference was observed in the American region. Insufficient data prevented comparisons over time for the African and South-East Asian regions and globally. Based on 2015-2021 HCV incidence, the global decline needed to meet the 2030 WHO target is 76.7% (95%UI: 71.8%-81.3%), while the global number of new annual HCV infections attributed to injecting drug use is 833,760 (95%UI: 493,716–1,544,395).
Interpretation: A substantial increase in HCV prevention is needed globally to achieve the WHO HCV elimination target on incidence among PWID.
| Original language | English |
|---|---|
| Journal | The Lancet Gastroenterology and Hepatology |
| Publication status | Accepted/In press - 20 Dec 2024 |
