Characteristics of post-overdose outreach programs and municipal-level opioid overdose in Massachusetts

•Post-overdose outreach programs are growing in scope and number.•How post-overdose outreach program practices affect overdose rates is unknown.•Fatal overdose rates were lower in municipalities where programs offered more social services.•Outreach intensity was associated with fewer opioid-related 911 calls in some cases.•Provision of social services (housing, transport, food, employment) may be key to program success.