Substance Use Prevalence and Patterns in Vulnerable Populations: A Systematic Review and Meta-Analysis.

Area of Science:

• Public Health
• Epidemiology
• Substance Abuse Research

Background:

• Vulnerable populations, including refugees, migrants, homeless individuals, and socially excluded adolescents, face unique risks for substance use.
• Understanding the prevalence and patterns of alcohol and other drug use in these groups is critical for public health interventions.

Purpose of the Study:

• To estimate the prevalence and patterns of alcohol and other drug use among vulnerable populations.
• To assess the quality and certainty of the evidence using PRISMA 2020 reporting standards and GRADE criteria.

Main Methods:

• A systematic review and meta-analysis of 18 observational studies (over 98,000 participants) were conducted.
• Searches covered major databases (PubMed, Scopus, etc.) from 2010-2025, focusing on substance use in defined vulnerable groups.
• Pooled prevalence estimates were calculated using random-effects models, with risk of bias and evidence certainty assessed.

Main Results:

• The pooled prevalence of alcohol use was 7.4% (95% CI 6.6-8.5%) with low heterogeneity.
• The pooled prevalence of any drug use was 26.4% (95% CI 16.8-38.8%) with high heterogeneity.
• Homeless and displaced adults showed higher prevalence than adolescents and migrants; overall evidence certainty was moderate.

Conclusions:

• Substance use, especially non-alcohol drugs, is significantly more prevalent in vulnerable populations.
• Social exclusion, homelessness, and forced migration increase substance use risks, necessitating tailored prevention, harm-reduction, and mental health strategies.
• Findings can inform policy and interventions in humanitarian and low-resource settings.