What are the true medical concerns facing unsheltered homeless adults?

Introduction: Estimates of behavioral and physical health conditions among unsheltered populations are often used to guide policy initiatives for healthcare and housing, yet robust, disease-specific prevalence estimates remain limited. We address this gap by leveraging multiple data sources to generate more reliable estimates of specific disease conditions for unsheltered adults. Methods: We triangulate data from three sources in Los Angeles County, which has the largest unsheltered population in the US: a probability-based survey of adults experiencing homelessness ( Results: Across sources, median prevalence was 40% for mental health conditions (range: 40%-61%) and 33% for substance use conditions (range: 31%-43%). Post-traumatic stress disorder and major depression were the most common mental health conditions (median 22%), and stimulant use disorder was the most common substance use condition (median 17%). Physical health conditions were more common than both mental health and substance use conditions overall (median 57%; range: 49%-73%). Conclusion: These findings underscore that housing and health care are complementary components of care and support, integrating field-based medical services with permanent housing investments.