Modelling the Impact of Prevention and Treatment Interventions on HIV and Hepatitis C Virus Transmission Among People Who Inject Drugs in Kenya

Abstract

Background: People who inject drugs (PWID) in Kenya have a high prevalence of HIV (14-26%) and HCV (11-36%). Needle and syringe programmes (NSP) and antiretroviral therapy (ART) have high coverage among PWID, while HCV treatment and opioid substitution therapy (OST) access is low. Methods: A dynamic model of HIV (sexual and injecting-related) and HCV (injecting-related) transmission among PWID was calibrated using Bayesian methods to data from Nairobi and the Coastal region. We projected the impact of existing coverage levels of interventions (ART: 64-66%; OST: 4-7%; NSP: 54-56%) in each setting, and the impact over 2020-2030 of increasing the coverage of OST (50%) and NSP (75%; full HR), ART (UNAIDS 90-90-90 target), HCV treatment (1000 over 5 years), and reducing HIV sexual risk by 75%. We estimated HCV treatment levels needed to reduce HCV incidence by 90% with or without full HR. Findings: Since 2013, HR has averted 15.1-20.6% (range in medians across settings) of HIV infections and 29.0-31.6% of HCV infections across Nairobi and the Coastal region, with most impact being due to NSP. Conversely, ART has only averted <5% of HIV infections since 2004 because of sub-optimal viral suppression (28-48%). Going forward, Full HR and ART could reduce HIV incidence by 58.2-62.0% and HCV incidence by 62.6-81.6% by 2030 across these settings. If sexual risk is also reduced, HIV incidence would reduce by 77.1-81.4%. Alongside full HR, treating 896 PWID over 2020-2025 could reduce HCV incidence by 90% by 2030. Interpretation: Existing interventions have had moderate impact on HIV and HCV transmission in Kenya, but may have substantial impact if scaled-up. However, to achieve HIV and HCV elimination, reductions in sexual risk are needed and a scale-up in HCV treatment.

Methods and indicators to validate country reductions in incidence of hepatitis C virus infection to elimination levels set by WHO

“…We used projections from 17 dynamic HCV transmission models [14][15][16][17][18][19][20][21][22][23][24][25][26][27] to examine whether four different indicators could be used to validate the relative HCV incidence target, which was defined as an 80% or 90% decrease in HCV incidence since baseline, depending on the study. We also considered if an absolute prevalence indicator could be used to validate an absolute incidence target.…”

“…The extent to which other HCV-specific indicators, which may be more easily measured, could be used as reliable alternatives to validate whether the HCV incidence target has been achieved has not been previously explored. Mathematical modelling conducted by our groups has been used to project future trends in chronic HCV prevalence and incidence following the scale-up of HCV treatment, and in some cases, HCV preventative measures, in a broad range of settings globally [14][15][16][17][18][19][20][21][22][23][24][25][26][27] . These models can be extended to examine how well trends in chronic HCV prevalence and coverage levels for programmatic indicators of HCV testing, treatment and preventative interventions track HCV incidence.…”

Barriers and Facilitators of HIV and Hepatitis C Care Among People Who Inject Drugs in Nairobi, Kenya: A Qualitative Study with Peer Educators

“…To address logistical and financial barriers, including mobility to and from villages, OST services should expand to include more convenient treatment options like take-home buprenorphine, which has been associated with improved HIV/HCV care outcomes [32,33]. Currently, methadone is Kenya's standard of care for OST; however, service coverage is limited and requires patients to attend daily clinic appointments which presents time, financial and logistic barriers for PWID [17,19]. Early concerns pointed to the effectiveness, misuse and increased overdose risks associated with take-home buprenorphine treatment; however, new evidence highlights the multiple benefits, including increased HIV/HCV treatment initiation and adherence, negative opioid urinalysis, HIV viral suppression and HCV viral clearance among PWID [32][33][34].…”

“…Kenya's Ministry of Health supports the collaboration of healthcare providers and harm reduction organizations that have established rapport with PWID communities in order to address the HIV and HCV epidemics [14][15][16]. Harm reduction programs are largely credited with reducing HIV and HCV incidence among PWID through needle syringes programs (NSPs), HIV counseling and testing services, social services (e.g., meals, shower facilities) and healthcare referrals [9,17]. Common healthcare referrals include HIV and HCV care, wound care and opioid substitution therapy (OST), with several OST clinics providing more comprehensive healthcare services by offering both methadone and HIV treatment to PWID [18].…”

An intensive model of care for hepatitis C virus screening and treatment with direct‐acting antivirals in people who inject drugs in Nairobi, Kenya: a model‐based cost‐effectiveness analysis

“…We utilized an existing dynamic compartmental model of HIV and HCV transmission among current and former PWID in Nairobi [25] to evaluate health outcomes and costs of the HCV treatment intervention in comparison to no treatment. The model allowed us to capture both the individual (preventing or slowing down HCV disease progression) and population benefits (preventing new infections) of treatment.…”