Age at death in elderly cohorts of four European countries of the Seven Countries Study: the role of comorbidities

Abstract

To study age at death (AD) in elderly men as a function of risk factors and morbid conditions in a 25-year follow-up. Men enrolled in the Seven Countries Study belonging to 8 cohorts in 4 European countries (Finland, The Netherlands, Italy and Serbia) were examined between 1984 and 1989 (aged 65-84years) with measurement of some cardiovascular risk factors and recording of a few major morbid conditions. AD was measured after 25-year follow-up and used in multiple linear regression (MLR) models as dependent variable; while, risk factors and morbid conditions had the role of independent variables. Out of 2457 men, 2290 died during 25-year follow-up. Overall mean AD was of 82.0years and slightly different across cohorts, the lowest being recorded in Finland. Age at entry examination and HDL cholesterol were directly associated with AD; while, blood pressure, heart rate, smoking habits and morbid conditions (major cardiovascular diseases, either independently or combined together with diabetes, chronic bronchitis, cancer and silent ECG abnormalities) were inversely related to AD. Body mass index had a parabolic relation with AD with longer survival for levels around 24 units; while, total serum cholesterol was not related to AD. However, only three independent variables were statistically significant when tested in each individual country (age, heart rate and stroke). In a MLR model, where a comorbidity score was entered as independent variable (everything else being equal), the presence of 1 morbid condition was associated with a reduced AD by 1.87years that increased up to 6.39years when 4 morbid conditions were present. AD seems a valuable indicator of all-cause mortality when the study population has reached or approached the extinction.