Twin Research

Articles

Heritability and Validity of Healthy Physical Aging (Wellness) in Elderly Male Twins

Terry Reeda1 c1 and Danielle M. Dicka2

a1 Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, USA. treed@iupui.edu

a2 Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, USA.

Abstract

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 NASNRC 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.

Correspondence:

c1 Address for correspondence: Terry E. Reed, PhD, Department of Medical & Molecular Genetics, Indiana University School of Medicine, 975 W. Walnut Street, IB — 130, Indianapolis, IN 46202 USA

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