A Danish population-based twin study on general health in the elderly

Objectives: To study the relative influence of genetic and environmental factors on self-rated health and hospitalization patterns in the elderly. Methods: A survey among all 3,099 Danish twins ages 75 years and older identified in the Danish Twin Registry. An interview was conducted with 77% of the twins. The number of hospitalizations in the previous 18 years was obtained through register linkage, thereby obtaining health information on 96% of the study population, including all nonresponders. Results: Structural equation modeling suggested that approximately a quarter of the variation in the liability to self-reported health and the number of hospitalizations could be attributed to genetic factors. The remaining variation was most likely due to nonfamilial environment. Analyses of the hospitalization patterns of proxy responders and nonresponders suggest that the estimates of the genetic influence on health outcomes in the study are conservative. Discussion: The present study indicates that variation in general health among the elderly is partly explained by genetic factors.