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.