Ten-year follow-up for male twins divided into high- or low-risk groups for ischemic heart disease based on risk factors measured 25 years previously

PURPOSE: To undertake medical follow-up in white males in the National Hear t, Lung, and Blood Institute (NHLBI) twin study, previously divided on the basis of cardiovascular disease risk factors. METHODS: Tree structured survival analysis (TSSA) used at a mean age of 63 years to classify twins into high and low risk subgroups for ischemic heart disease (IHD) found that subjects at a mean age of 48 years were at highes t risk with high systolic blood pressures and low high density lipoproetin cholesterol levels. Low risk subjects had lower blood pressures, better pul monary function tests, and a negative family history for IHD or Low post lo ad plasma glucose Levels. Medical record review was performed ten years lat er at the 4th Examination of the NHLBI twin cohort conducted in 1995-1997. RESULTS: The percentage of men in the NHLBI twin study who died nearly trip led (from 9.3% to 25.8%) in the ten-year period between the ages of 63 and 73 years. Deaths have tended tea remain higher in DZ than MZ twins (27.8% v ersus 23.7%). At Exam 4, the relative risk of IHD (fatal or nonfatal) was 5 .24 times higher for those in the high risk group than those in the low ris k class (95% confidence limit 2.72-10.07, p < 0.0001 and 5.86 for any cardi ovascular disease (95% confidence limit 3.03-11.33). The proportion of deat hs from IHD in subjects with a high risk profile at entry was 51.7%, and 70 .0% had died from all cardiovascular related disease. CONCLUSION: The present results indicate TSSA remained effective in classif ying subjects into subgroups with greater risk of morbidity and mortality r elated to cardiovascular disease after ten additional years. Ann Epidemiol 2000;10:278-284. (C) 2000 Elsevier Science Inc. All rights reserved.