Abstract / Summary
Summary: Background: Climate-related disasters can disrupt health-care delivery and treatment continuity. Evidence on their effects on opioid dispensing in middle-income countries remains scarce. We assessed whether the May 2024 floods were associated with changes in outpatient opioid dispensing in Rio Grande do Sul, Brazil. Methods: We conducted a retrospective ecological time-series study using official Brazilian Ministry of Health data on codeine, morphine, and methadone dispensations from 2015 to 2025. Monthly rates per 10,000 inhabitants were modelled with quadratic secular and seasonal terms, month-specific effects from May 2024 to May 2025, and Newey–West standard errors. Analyses were stratified by opioid and age, applied to Minas Gerais as a comparison state, and repeated after excluding 2020–2021. Findings: Among 131 states-months analysed, May 2024 was associated with an abrupt reduction of 68.86 dispensed units per 10,000 inhabitants relative to the counterfactual (95% CI −73.57 to −64.15; p < 0.001), followed by a smaller reduction in June (−14.81 per 10,000 inhabitants; 95% CI −21.12 to −8.51; p < 0.001). Females accounted for 63.6% of all dispensed units. From July to September, dispensing no longer differed significantly from expected levels, followed by an uneven recovery with intermittent above-expected increases. Disruption was most prolonged for morphine. The immediate decline remained after excluding the COVID-19 period. Interpretation: The abrupt, transient decline suggests that the floods disrupted the health-care network and continuity of access to controlled medicines. Although aggregate dispensing recovered, this does not ensure that therapeutic continuity was fully restored for all patients. Disaster preparedness and response should therefore prioritise health-system resilience capable of preserving essential treatments during climate-related emergencies. Funding: Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (FAPERGS), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), and Instituto Nacional de Ciência e Tecnologia em Saúde Mental Digital (INCT-SMD).