Heritability and validity of healthy physical aging (wellness) in elderly male twins.

The authors define a trait "wellness" for good health in 6109 men in the National Academy of Sciences-National Research (NAS-NRC) twin panel aged 70 years and up surveyed by mail in the fall of 1998. Men who responded that they had not had a heart attack, coronary surgery, stroke, diabetes or prostate cancer in the survey questionnaire (Q8) met the broad definition of wellness. A more narrow definition included the absence of hypertension. Genetic analysis indicated that over 50% of the population variance for liability to either wellness definition was genetic. A subset of the NAS-NRC twins also participates in the National Heart, Lung and Blood Institute (NHLBI) twin study. NHLBI examinations and medical record review was done in 1986-1987 and 1995-1997 for 389 individuals who completed Q8. Excellent agreement (kappa > 0.8) was found between Q8 and outcome review for each condition comprising the wellness definition, ranging from 0.81 for coronary surgery to 0.88 for diabetes. Substantial agreement (kappa = 0.67) was found for hypertension. Kappa values for wellness were 0.82 for the broader definition and 0.74 if high blood pressure was included. Fraternal twin-pairs concordant for the wellness definitions are currently being recruited for linkage studies.