The relation of chronic diseases to all-cause mortality risk - The Seven Countries Study

The relation of chronic conditions on all-cause mortality in population samples was studied based on observations from the Seven Countries Study. The objective of this work was to study the risk of death during a 15-year follow-up of middle-aged men in relation to six chronic diseases. Fifteen cohorts of men aged 50-69, totalling 8122 subjects, were examined around 1970 in seven countries: Finland, The Netherlands, Italy, Croatia (former Yugoslavia), Serbia (former Yugoslavia), Greece and Japan. Clinical diagnoses findings were made for coronary heart disease (CHD), 'other heart diseases' (OTH), peripheral arterial disease (PAD), stroke (STR), chronic obstructive pulmonary disease (COPD), and diabetes mellitus (DIAB). All-cause mortality was assessed in the subsequent 15 years. Death rates and relative risks were estimated from crude data, and in proportional hazards models after adjustment for age, systolic blood pressure and serum cholesterol level, cigarette smoking and body mass index. Large regional differences were found in the prevalence of the six conditions. Weak relations were found between population prevalence of each disease and population death rates for that disease. Among cohorts the relative risk of death in 15 years from any cause, adjusted for other risk factors, showed little variation among countries. Pooled relative risks, adjusted by the inverse of variance (with 95% CI) were: for CHD, 1.81 (1.60-2.06); for OTH, 1.47 (1.28-1.69); for PAD, 1.64 (1.39-1.93); for STR, 1.56 (1.23-1.98); for COPD, 1.67 (1.48-1.88); and for DIAB, 1.75 (1.43-2.15). The smallest variability of prognosis among countries was found for CHD, OTH and DIAB; the largest for PAD, STR and COPD. Despite simple clinical diagnostic procedures and large differences in prevalence, the relation of established prevalent conditions to subsequent all-cause mortality is relatively uniform among countries and across these conditions, with a relative risk of dying in 15 years usually ranging between 1.5 and 2.0.