Decreasing systolic blood pressure and declining mortality rates in an untreated population: results from the Copenhagen City Heart Study

Objective: The aim of the present study was to evaluate developments in 30 years mortality risk that may be associated with developments in population systolic blood pressure (SBP) and to evaluate possible secular trends in BP-associated mortality risk in the untreated population. Design: The Copenhagen City Heart Study is a prospective longitudinal epidemiological study. The present analysis comprised participants from survey 1 (1976-78) and 3 (1991-94). Methods: BP measurements and other methods were fully standardized and unchanged throughout the observation period. Questionnaires were completed by the participants and double checked by the technicians while they were interviewing the participants. Results: 18 077 persons participated. Age, systolic BP, diastolic BP, cholesterol, BMI, diabetes, gender and habitual physical activity were significant predictors of all-cause death in all age groups. Risk factor adjusted risk for all-cause death was significantly lower in survey 3 compared with survey 1. Among elderly people, there was no development in mortality risk. In the age groups 40-49 years and 50-59 years there were survey differences indicating a significant trend towards longer life expectancy compared with their age-matched counterparts in survey 1. The association between BP and mortality remained unchanged. Conclusion: A declining risk of all-cause death was observed in the younger and middle-aged cohorts of the population. The decrease in systolic BP and decline in mortality risk in the same age groups points to a role of systolic BP in age-cohort differentiated improvements of life expectancy. The effect of systolic BP on mortality did not change during follow-up.