Genetic Factors and Susceptibility to Falls in Older Women

Objectives: To determine whether genetic influences account for individual differences in susceptibility to falls in older women.

Design: Prospective twin cohort study.

Setting: Research laboratory and residential environment.

Participants: Ninety-nine monozygotic (MZ) and 114 dizygotic (DZ) female twin pairs aged 63 to 76 from the Finnish Twin Cohort study.

Measurements: The participants recorded their falls on a calendar for an average+/-standard deviation of 344+/-41 days. Reported falls were verified via telephone interview, and circumstances, causes, and consequences of the fall were asked about.

Results: The total number of falls was 434, of which 188 were injurious; 91 participants had two or more falls. Casewise concordance was 0.61 (95% confidence interval (CI)=0.49-0.72) for MZ twins and 0.49 (95% CI=0.37-0.62) for DZ twins for at least one fall, 0.38 (95% CI=0.23-0.53) for MZ and 0.33 (95% CI=0.17-0.50) for DZ twins for at least one injurious fall, and 0.43 (95% CI=0.26-0.60) for MZ and 0.36 (95% CI=0.17-0.55) for DZ twins for recurrent falls. On average, the proportion of familial influences accounting for the individual differences in susceptibility to at least one fall was 30% and to recurrent falls was 40%; nongenetic familial and nonfamilial factors alone accounted for susceptibility to at least one injurious fall.

Conclusion: In community-dwelling older women, familial factors underlie the risk of falling but not the risk of injurious falls.