Modelling the impact of HIV and hepatitis C virus prevention and treatment interventions among people who inject drugs in Kenya

Virologic Nonsuppression and HIV Drug Resistance Among People Who Inject Drugs and Their Sexual and Injecting Partners in Kenya

We evaluated the prevalence and correlates of HIV viral nonsuppression and HIV drug resistance (HIV-DR) in a cohort of people who inject drugs living with HIV (PWID-LH) and their sexual and injecting partners living with HIV in Kenya. HIV-DR testing was performed on participants with viral nonsuppression. Of 859 PWID-LH and their partners, 623 (72.5%) were on antiretroviral therapy (ART) ≥4 months and 148/623 (23.8%) were not virally suppressed. Viral nonsuppression was more common among younger participants and those on ART for a shorter duration. Among 122/148 (82.4%) successfully sequenced samples, 55 (45.1%) had detectable major HIV-DR mutations, mainly to non-nucleoside and nucleotide reverse transcriptase inhibitors (NNRTI and NRTI). High levels of HIV-DR among those with viral nonsuppression suggests need for viral load monitoring, adherence counseling, and timely switching to alternate ART regimens in this key population.

Comparison of Empirically Derived and Model-Based Estimates of Key Population HIV Incidence and the Distribution of New Infections by Population Group in Sub-Saharan Africa

BACKGROUND

The distribution of new HIV infections among key populations, including female sex workers (FSWs), gay men and other men who have sex with men (MSM), and people who inject drugs (PWID) are essential information to guide an HIV response, but data are limited in sub-Saharan Africa (SSA). We analyzed empirically derived and mathematical model-based estimates of HIV incidence among key populations and compared with the Joint United Nations Programme on HIV/AIDS (UNAIDS) estimates.

METHODS

We estimated HIV incidence among FSW and MSM in SSA by combining meta-analyses of empirical key population HIV incidence relative to the total population incidence with key population size estimates (KPSE) and HIV prevalence. Dynamic HIV transmission model estimates of HIV incidence and percentage of new infections among key populations were extracted from 94 country applications of 9 mathematical models. We compared these with UNAIDS-reported distribution of new infections, implied key population HIV incidence and incidence-to-prevalence ratios.

RESULTS

Across SSA, empirical FSW HIV incidence was 8.6-fold (95% confidence interval: 5.7 to 12.9) higher than total population female 15-39 year incidence, and MSM HIV incidence was 41.8-fold (95% confidence interval: 21.9 to 79.6) male 15-29 year incidence. Combined with KPSE, these implied 12% of new HIV infections in 2021 were among FSW and MSM (5% and 7% respectively). In sensitivity analysis varying KPSE proportions within 95% uncertainty range, the proportion of new infections among FSW and MSM was between 9% and 19%. Insufficient data were available to estimate PWID incidence rate ratios. Across 94 models, median proportion of new infections among FSW, MSM, and PWID was 6.4% (interquartile range 3.2%-11.7%), both much lower than the 25% reported by UNAIDS.

CONCLUSION

Empirically derived and model-based estimates of HIV incidence confirm dramatically higher HIV risk among key populations in SSA. Estimated proportions of new infections among key populations in 2021 were sensitive to population size assumptions and were substantially lower than estimates reported by UNAIDS.

Cost-effectiveness of Hepatitis C virus self-testing in four settings

Globally, there are approximately 58 million people with chronic hepatitis C virus infection (HCV) but only 20% have been diagnosed. HCV self-testing (HCVST) could reach those who have never been tested and increase uptake of HCV testing services. We compared cost per HCV viraemic diagnosis or cure for HCVST versus facility-based HCV testing services. We used a decision analysis model with a one-year time horizon to examine the key drivers of economic cost per diagnosis or cure following the introduction of HCVST in China (men who have sex with men), Georgia (men 40-49 years), Viet Nam (people who inject drugs, PWID), and Kenya (PWID). HCV antibody (HCVAb) prevalence ranged from 1%-60% across settings. Model parameters in each setting were informed by HCV testing and treatment programmes, HIV self-testing programmes, and expert opinion. In the base case, we assume a reactive HCVST is followed by a facility-based rapid diagnostic test (RDT) and then nucleic acid testing (NAT). We assumed oral-fluid HCVST costs of $5.63/unit ($0.87-$21.43 for facility-based RDT), 62% increase in testing following HCVST introduction, 65% linkage following HCVST, and 10% replacement of facility-based testing with HCVST based on HIV studies. Parameters were varied in sensitivity analysis. Cost per HCV viraemic diagnosis without HCVST ranged from $35 2019 US dollars (Viet Nam) to $361 (Kenya). With HCVST, diagnosis increased resulting in incremental cost per diagnosis of $104 in Viet Nam, $163 in Georgia, $587 in Kenya, and $2,647 in China. Differences were driven by HCVAb prevalence. Switching to blood-based HCVST ($2.25/test), increasing uptake of HCVST and linkage to facility-based care and NAT testing, or proceeding directly to NAT testing following HCVST, reduced the cost per diagnosis. The baseline incremental cost per cure was lowest in Georgia ($1,418), similar in Viet Nam ($2,033), and Kenya ($2,566), and highest in China ($4,956). HCVST increased the number of people tested, diagnosed, and cured, but at higher cost. Introducing HCVST is more cost-effective in populations with high prevalence.

Modeling the Impacts of Prevention and Treatment Interventions on Hepatitis C Among People Who Inject Drugs in China

INTRODUCTION

Injection drug use is the main transmission route of hepatitis C virus (HCV) in China. The prevalence of HCV remains high at 40-50% among people who inject drugs (PWID). We developed a mathematical model to predict the impacts of different HCV intervention strategies on the HCV burden in Chinese PWID by 2030.

METHODS

We developed a dynamic deterministic mathematical model to simulate the transmission of HCV among PWID in China between 2016 and 2030, using domestic data based on the real cascade of HCV care. We considered various intervention scenarios, including treatment regimens, harm reduction program (HRP) coverage, enhanced testing and referral for treatment.

RESULTS

HCV incidence will exhibit a gradual but slow declining trend from 12,970 in 2016 to 11,761 in 2030 based on current screening and treatment practices among PWID (scenario 1). Scaled-up HCV screening and treatment integrated with HRPs (scenario 8) demonstrated the most substantial reduction in HCV burden, being the only intervention scenario that could achieve the World Health Organization's (WHO's) HCV elimination target. Specifically, the HCV incidence in 2030 is projected to be reduced by 81.42%, and HCV-related deaths are projected to be reduced by 91.94%.

CONCLUSION

Our study indicates that achieving WHO elimination targets is an extremely challenging goal that requires substantial improvements in HCV testing and treatment among PWID (scenario S8). The findings suggest that coordinated improvements in testing, treatment, and harm reduction programs could greatly reduce the HCV burden among PWID in China, and urgent policy changes are needed to integrate HCV testing and treatment into existing HRPs.

Predictors of hepatitis C cure among people who inject drugs treated with directly observed therapy supported by peer case managers in Kenya

BACKGROUND & AIMS

Directly observed therapy (DOT) maximizes adherence and minimizes treatment gaps. Peer case managers (PCM) have also shown promise as a component of integrated HCV treatment strategies. DOT and PCM-support have been underexplored, particularly in low- and middle-income countries (LMICs). The objective of this study was to evaluate predictors of sustained virologic response (SVR) among people who inject drugs (PWID) attending medication-assisted treatment (MAT) and needle and syringe programs (NSP) sites in Kenya.

METHODS

We recruited PWID accessing MAT and NSP in Nairobi and Coastal Kenya. PWID were treated with ledipasvir/sofosbuvir using DOT supported by PCMs. We used bivariate and multivariate logistic regression to examine the impact of sociodemographic, behavioral, and clinical factors on SVR.

RESULTS

Among 92 PWID who initiated HCV treatment, 79 (86%) were male with mean age of 36.3 years (SD=±6.5); 38 (41%) were HIV-positive, and 87 (95%) reported injecting drugs in the last 30 days. Just over half of participants were genotype 1a (55%), followed by genotype 4a (41%) and mixed 1a/4a (3%). Most participants, 85 (92%) completed treatment and 79 (86%) achieved SVR. While sociodemographic and behavioral factors including recent injection drug use were not significantly associated with achieving SVR, being fully adherent (p=0.042), number of doses taken (p=0.008) and treatment completion (p= 0.001) were associated with higher odds of achieving SVR.

CONCLUSIONS

DOT with PCM-support was an effective model for HCV treatment among PWID in this LMIC setting. Adherence was the most important driver of SVR suggesting DOT and PCM support can overcome other factors that might limit adherence. Further research is necessary to ascertain the effectiveness of other models of HCV care for PWID in LMICs given NSP and MAT access is variable, and DOT may not be sustainable with limited resources.