Kirby Institute Seminar Series presents
Global epidemiology of injecting drug use
Background: Sharing of equipment used for injecting drug use (IDU) is a substantial cause of disease burden and contributor to blood borne virus transmission. We undertook multiple global systematic reviews to identify prevalence of IDU among people aged 15-64 years; sociodemographic characteristics of and risk factors for people who inject drugs (PWID); and HIV, hepatitis C (HCV) and hepatitis B (HBV) prevalence amongst PWID.
Methods: Consistent with GATHER and PRISMA guidelines, we systematically searched peer-reviewed (Medine, Embase, and PsycINFO), internet, and grey literature databases, and disseminated data requests to international experts and agencies. We searched for data on IDU prevalence, characteristics of PWID including gender, age, and sociodemographic and risk characteristics, and prevalence of HIV, HCV and HBV among PWID.
Findings: We reviewed 55,671 papers/reports, with data ultimately extracted from 1,147 eligible papers/reports. Evidence of IDU was documented in 179 out of 206 countries/territories covering 99% of the population aged 15-64 year), an increase of 31 countries (predominantly in Sub-Saharan Africa and the Pacific Islands) since a 2008 review; IDU prevalence estimates were identified in 83 countries. We estimate that there are 15∙8 million (uncertainty intervals (UI) 10∙1-24∙2 million) PWID aged 15-64 years globally, with 3∙2 million women and 12∙6 million men. Gender composition varied by location: in North America and Australasia women were estimated to comprise 30∙0% and 33∙4% of PWID respectively, compared to 3∙1% in South Asia. Globally, we estimate that 16∙9% (UI 9.9-24∙6%) of PWID are living with HIV; 52∙5% (UI 41.9-63.3%) are HCV-antibody positive and 8∙9% (UI 4.7-13.9%) HBsAg-positive; there is substantial geographic variation in these levels. Globally, we estimate 82∙9% (UI 76∙6-88∙9%) of PWID mainly inject opioids, and 29∙2% (UI 22∙5-36∙2%) mainly inject stimulants. We estimate that around one in four PWID globally are under 25 years old (27∙8%; UI 20∙8-36∙6%), one-fifth recently (≤past year) experienced homelessness or unstable housing (21∙6%; UI 15∙8-27∙8%), and six in ten have experienced incarceration (58∙0%; UI 50∙6-65∙2%).
Interpretation: IDU has been identified in more countries since 2008, largely in low- and middle-income countries in Africa. Across all countries, a substantial number of PWID are living with HIV and HCV, and are exposed to multiple adverse risk environments that increase health harms.
Global coverage of key prevention interventions for people who inject drugs
Background: People who inject drugs (PWID) are a key population affected by the global HIV and hepatitis C virus (HCV) epidemics. HIV and HCV prevention interventions for PWID include needle and syringe programmes (NSP), opioid substitution therapy (OST), HIV counselling and testing, HIV antiretroviral therapy (ART), and condom distribution programmes. We aimed to produce country-level, regional, and global estimates of coverage of NSP, OST, HIV testing, ART, and condom programmes for PWID.
Methods: We completed searches of peer-reviewed (MEDLINE, Embase, and PsycINFO), internet, and grey literature databases, and disseminated data requests via social media and targeted emails to international experts. Programme and survey data on each of the named interventions were collected. Programme data were used to derive country-level estimates of the coverage of interventions in accordance with indicators defined by WHO, UNAIDS, and the UN Office on Drugs and Crime. Regional and global estimates of NSP, OST, and HIV testing coverage were also calculated. The protocol was registered on PROSPERO, number CRD42017056558.
Findings: In 2017, of 179 countries with evidence of injecting drug use, some level of NSP services were available in 93 countries, and there were 86 countries with evidence of OST implementation. Data to estimate NSP coverage were available for 57 countries, and for 60 countries to estimate OST coverage. Coverage varied widely between countries, but was most often low according to WHO indicators (<100 needle-syringes distributed per PWID per year; <20 OST recipients per PWID per year). Data on HIV testing were sparser than for NSP and OST, and very few data were available to estimate ART access among PWID living with HIV. Globally, we estimate that there are 33 (uncertainty interval [UI] 21–50) needle-syringes distributed via NSP per PWID annually, and 16 (10–24) OST recipients per 100 PWID. Less than 1% of PWID live in countries with high coverage of both NSP and OST (>200 needle-syringes distributed per PWID and >40 OST recipients per 100 PWID).
Interpretation: Coverage of HIV and HCV prevention interventions for PWID remains poor and is likely to be insufficient to effectively prevent HIV and HCV transmission. Scaling up of interventions for PWID remains a crucial priority for halting the HIV and HCV epidemics.