A twin study of erectile dysfunction in the Vietnam Era Twin (VET) Registry

• Main Author: Fischer, Mary Ellen
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01.01.2002
• Subjects: Genetics; Public health; Risk factors; Sexual disorders; Vietnam
• ISBN: 049373368X; 9780493733685

The prevalence and risk factors for erectile dysfunction (ED) in a sample of middle-aged males, all members of the Vietnam Era Twin (VET) Registry, were determined. Adjustment for genetic confounding and potential missing data bias was performed. The heritability of ED and the extent to which ED and hypertension share genetic influences were estimated. The VET Registry includes 7,368 male-male twin pairs born between 1939 and 1957 who both served on active duty during the Vietnam conflict era (1965–1975). Data from the 4 major surveys of the Registry were used in this study. The extent of missing data in the Registry was estimated and using mixed effects regression techniques, the significant baseline predictors of having missing data were ascertained. Mixed effects regression was also used to determine the risk factors for ED for monozygotic twins in the Registry. Overall effects were partitioned into between pair and within pair effects where the within pair effects were free of genetic confounding. Missing data bias in the risk factor study was assessed through the use of the results of the missing data evaluation. The heritability of ED was estimated using univariate structural equation modeling and bivariate structural equation modeling was used to determine the degree to which ED and hypertension share common genetic and environmental influences. A number of factors, including demographic and physical health items, were found to be significantly related to the probability of having information in the VET Registry. In the ED risk factor component of the study, a substantial number of middle-aged male twins were found to have ED. Although results with respect to ED risk factors were consistent with previous literature, after controlling for genetic effects none of the established risk factors continued to be significant, with the possible exception of advanced education. The heritability of ED was estimated to be approximately 35%. ED and hypertension were found to share a moderate degree of genetic influence.