Nongenetic factors associated with stress urinary incontinence

To explore the role of hereditary and environmental factors on the development of stress urinary incontinence in a large cohort of identical and nonidentical twins.

This is a large, population-based, classic twin study of twin sisters recruited to complete a health survey at the world's largest annual twins festival during 2003-2008. Concordance rates were calculated and structural equation models were used to estimate the contribution of genetic effects compared with environmental factors toward the development of stress urinary incontinence.

Eight hundred eighty-two twin sister pairs (n=1,764), including 765 identical and 117 nonidentical twin sister pairs, completed the questionnaires. Sequential structural equation modeling revealed that common environmental factors contributed 77.6% (95% confidence interval [CI], 41.4-83.8; P<.001) of the variance and unique environmental factors contributed 20.9% (95% CI, 15.8-26.7; P<.001) of the variance. The effect of genetics was not statistically significant at 1.49% (95% CI, 0.0-38.8; P=.46).

Female stress urinary incontinence is more a consequence of environmental risk factors than heredity. This epidemiologic insight should be considered in preventive health efforts.

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