Purpose: Clinical studies have shown strong family influences on individual health, but the aggregate importance of family effects for population health is unknown. Our objective was to estimate, at a population level, the variance in individual health status attributable to the family.
Methods: Secondary data were used from the Community Tracking Study, a stratified random sample of the US population. Hierarchical linear modeling was used to estimate the individual and family components of health status. The setting was 60 US communities, which account for approximately one half of the population. Participants were US residents aged 18 years and older who shared a household with family members in the study (N = 35,055). Main outcome measures were the Short Form-12 (SF-12) self-reported physical and mental subscales.
Results: Depending on the family configuration, 4.5% to 26.1% of the variance in individual health status was derived from the family. The proportion was highest for older married persons. The family effect on health status was generally similar for physical and mental health. Including age, family income, and health insurance status in the regression equations moderately reduced the family variance component.
Conclusions: At a population level, the family contribution to individual health status is measurable and substantial. The shared characteristics of income and health insurance account for only a modest portion of the effect. Health policy and interventions should place more emphasis on the family's role in health.