My family member's health and my mental health: A longitudinal matched cohort study.

Having a close relative or family member suffer a serious injury or illness was associated with significantly lower mental health scores in the exposed group compared to the unexposed group.

• Data were sourced from the Household, Income and Labour Dynamics in Australia (HILDA) survey, a longitudinal cohort of Australian adults.
• A propensity score matching-difference in differences (PSM-DiD) identification approach was used to address both observable and unobservable selection bias.
• The mental health effects were more pronounced among females compared to males.
• The mental health effects set in after two years post-onset of the injury or illness.

Individuals in the exposed group had higher odds of being time stressed compared to the unexposed group.

• Time stress started contemporaneously with the onset of the family member's injury or illness.
• Time stress persisted through to the sixth-year post-injury or illness.
• Males were more time stressed than females following a family member's serious injury or illness.
• The PSM-DiD approach was used to isolate the causal effect from selection bias.

The mental health effects of a family member's serious injury or illness were more pronounced among individuals with low social capital.

• Further analyses examined heterogeneity by social capital levels.
• Those with low social capital experienced more pronounced mental health deterioration compared to those with higher social capital.
• This finding suggests social capital moderates the spillover mental health effects of a family member's illness or injury.

The burden of illness extends beyond the affected individual, producing spillover mental health effects on close family members.

• The biobehavioral family model, which posits that an individual's biobehavioral reactivity is influenced by their family's health, provided the theoretical framework.
• The authors argue that evaluations of illness impact should consider spillover effects including health losses to close family members.
• Social support packages designed to improve a person's health recovery post-injury or illness should account for potential unintended health losses to close relatives.
• Ignoring these spillover impacts 'could lead to sub-optimal outcomes for families and society.'