Trends in HIV incidence following scale-up of harm reduction interventions among people who inject drugs in Kachin, Myanmar, 2008–2020: analysis of a retrospective cohort dataset

BACKGROUND: People who inject drugs (PWID) in Kachin, Myanmar, have a high HIV prevalence (>40%), but there is no data on incidence. We used HIV testing data from three harm reduction drop-in centres (DIC) in Kachin (2008–2020) to determine HIV incidence trends among PWID and associations with intervention uptake. METHODS: Individuals were HIV-tested at first DIC visit and periodically thereafter, during which demographic and risk behaviour data were collected. Two DIC provided opioid agonist therapy (OAT) from 2008. Monthly DIC-level needle/syringe provision (NSP) data was available from 2012. Site-level 6-monthly NSP coverage was denoted low, high, or medium if it was below the lower quartile, above upper quartile, between these quartiles of provision levels over 2012–2020, respectively. HIV incidence was estimated by linking subsequent test records for those initially testing HIV-negative. Associations with HIV incidence were examined using Cox regression. FINDINGS: Follow-up HIV testing data was available for 31.4% (2227) of PWID initially testing HIV-negative, with 444 incident HIV infections during 6266.5 person years (py) of follow-up. Overall HIV incidence was 7.1 per 100 py (95% confidence interval 6.5–7.8), which decreased from 19.3 (13.3–28.2) in 2008–11 to 5.2 per 100 py (4.6–5.9) in 2017–20. In the full PWID incidence dataset after adjustment for various factors, recent (≤6 weeks) injecting (aHR 1.74, 1.35–2.25) and needle sharing (aHR 2.00, 1.48–2.70) were associated with higher incidence, while longer injection careers were associated with reduced incidence (aHR 0.54, 0.34–0.86, for 2–5 yrs vs <2 yrs). In a reduced dataset including data on OAT access and NSP coverage (2012–2020 for two DIC providing OAT), being on OAT during follow-up was associated with reduced HIV incidence (aHR 0.36, 0.27–0.48, compared to never being on OAT) as was high NSP coverage (aHR 0.64, 0.48–0.84, compared to medium syringe coverage). INTERPRETATION: Although HIV incidence is high among PWID in Kachin, data suggests it has decreased since the scale-up in harm reduction interventions. FUNDING: US NIH, Médecins du Monde.