Trends and determinant factors for population blood pressure with 25 years of follow-up: results from the Copenhagen City Heart Study

OBJECTIVE: This study aimed to evaluate within-population trends in population blood pressure (BP) over 25 years and to identify important determinants for a changing population BP. DESIGN: Copenhagen City Heart Study is a prospective longitudinal epidemiological study. The study population (15 508) did not receive antihypertensive therapy. METHODS: The BP measurement was fully standardized and measurement method was unchanged throughout the observation period. A questionnaire concerning drinking habits, smoking, medical therapy and physical exercise was completed by the participants and double checked by the technicians. RESULTS: After an initial increase, population systolic BP (SBP) decreased. All risk factors were tested in the longitudinal model by means of a residual likelihood ratio test. The final model included sex, age and body mass index as significant factors and covariates. Two interactions were included. The first interaction 'agexsex' showed that the sex differences diminished with age. The second interaction 'agexsurvey' showed that the value of SBP in the young generations decreased survey by survey. SBP in the elderly also decreased survey by survey, but to a lesser degree. Diastolic BP (DBP) increased to a peak value in survey 3 and hereafter decreased. CONCLUSION: SBP decreased. body mass index, sex and age have an effect on population BP. A decreasing trend in SBP among new entrants is responsible for (part of) the observed decrease in population SBP. The decreasing SBP among the elderly was affected by the fact that an increasing number of the elderly population started antihypertensive medication. DBP decreased, but none of the investigated factors affected DBP.