Childhood Maltreatment and Mental-Physical Multimorbidity: A Quasi-Experimental Analysis of Canadian Survey Data Using Entropy Balancing

ObjectivesTo explore childhood maltreatment as a risk factor for mental-physical multimorbidity and examine gender as an effect modifier. MethodsWe analyzed data from the 2022 Mental Health and Access to Care Survey. We described sample characteristics with unweighted counts, survey-weighted percentages, and weighted chi-square tests. Missing data were addressed via multiple imputation. Entropy balancing adjusted for age, gender, LGBTQ2+ identity, visible minority group, and immigration status and multinomial logistic regression was used to estimate associations between the number of childhood maltreatment subtypes (physical abuse, sexual abuse, and exposure to domestic violence) reported and physical ([≥] 2 physical conditions but no mental), mental ([≥] 2 mental conditions but no physical), and mental-physical ([≥] 1 mental and physical condition) multimorbidity. Survey weights were applied during both entropy balancing and regression modeling. Effect modification by gender was examined and sub-analyses of mental- cardiometabolic, mental-inflammatory, mental-somatic multimorbidity, and subtype-specific exposures were conducted. Results8,967 respondents were included. Mental-physical multimorbidity increased with maltreatment: 3.4% (none, n=4647), 6.3% (1 type, n=2804), 10.1% (2 types, n=1208), and 18.2% (3 types, n=308). Adjusted odds ratios for mental-physical multimorbidity ranged from 2.15 (95% CI:1.90-2.44) for 1 type to 8.72 (95% CI:7.01-10.85) for 3 types compared to physical (aOR=1.31-2.00) and mental (aOR=1.90-3.63) multimorbidity. Men showed higher odds of mental-physical multimorbidity at high exposure (aOR=6.14, 95% CI:4.90-7.70 in women; aOR=13.96, 95% CI:9.58-20.34 in men) with varying effect sizes across disease areas. ConclusionChildhood maltreatment shows a strong dose-response association with mental- physical multimorbidity. Further research is needed to clarify gender-specific pathways.