War-related displacement, conflict intensity, and treatment delivery factors in opioid agonist maintenance treatment discontinuation following Russia's invasion of Ukraine: a national cohort study

Background Ukraine has Europe's second-largest HIV epidemic, driven mainly by injection opioid use. Opioid agonist maintenance treatment (OAMT) is the most effective treatment for opioid use disorder (OUD) and a key HIV prevention strategy. Following Russia's invasion of Ukraine on 24 February 2022, continuity of OAMT was threatened. We examined the effects of displacement, war exposure, and treatment delivery factors on OAMT discontinuation during the first two years of the expanded war. Methods In this retrospective analysis of a prospective national cohort study, we used individual-level data from Ukraine's national OAMT registry. Adults (≥18 years) with diagnosed OUD receiving OAMT in 252 government-operated clinics as of 23 February 2022 were followed through 1 January 2024. The primary outcome was treatment discontinuation. War exposure was classified using k-means clustering of six standardised regional indicators: air raids, explosions, artillery attacks, internal displacement, occupation days, and frontline days. Regions were categorised as low-intensity, high-intensity, or frontline. Displacement was modelled as a time-dependent variable in frailty-adjusted extended Cox proportional hazards models. Findings In total, 17,211 participants were included (14,554/17,211 (84.6%) men; mean age 38.9 years, with standard deviation=7.2). During follow-up, 5040/17,211 (29.3%) discontinued OAMT and 921/17,211 (5.4%) died. Compared with local patients in low-intensity regions, discontinuation risk was higher in high-intensity (aHR 1.74; 95% CI 1.40–2.15) and frontline regions (aHR 3.09; 95% CI 2.80–3.42). Internally displaced persons faced markedly elevated risk in low-intensity (aHR 3.55; 95% CI 2.92–4.32), high-intensity (aHR 5.90; 95% CI 4.52–7.69), and frontline regions (aHR 8.26; 95% CI 5.43–12.56). Optimal dosing (aHR 0.74; 95% CI 0.69–0.78) and unsupervised dosing (aHR 0.71; 95% CI 0.64–0.78) were protective. Females had higher discontinuation risk (aHR 1.20; 95% CI 1.11–1.30) than males. Interpretation Displacement and residence in high-intensity war regions were dominant drivers of OAMT discontinuation. Flexible dosing policies and continuity strategies for displaced patients are essential to sustain OAMT during war. Funding National Institute on Drug Abuse (R01DA033679, R01DA043125, R01DA045384, F31DA054861, R01DA054703).