Progression to hypertension in the non-hypertensive participants in the Flemish Study on Environment, Genes and Health Outcomes

Objective To evaluate the consistency between a randomly recruited Western European population and the participants of the Framingham Heart Study, with respect to the rates and determinants of progression to hypertension. Methods Among the non-hypertensive individuals enrolled in the Flemish Study on Environment, Genes and Health Outcomes, we assessed progression from optimal (< 120/80 mmHg), normal (120-129/80-84 mmHg) and high-normal ( 130-139/85-89 mmHg) blood pressure to hypertension (>= 140/ 90 mmHg). Our analysis included 781 women and 675 men (age range 10-77 years) who were followed up for a median of 4.6 years (interquartile range 2.4-8.1 years). Our statistical methods included Kaplan-Meier survival function estimates, the log-rank test and multiple Cox regression. Results In individuals younger than 50 years, 4-year progression rates associated with optimal, normal and high-normal blood pressure were 7.4% [95% confidence interval (CI) 5.5-9.3], 17.9% (95% CI 14.3-21.6) and 24.5% (95% CI 18.7-30.2), respectively. Corresponding 4-year rates of progression for individuals aged 50 years or older were 16.4% (95% CI 11.2-22.5), 26.3% (95% CI 19.8-32.9) and 54.0% (95% CI 45.7-62.3), respectively. In multivariate Cox regression, blood pressure category and body mass index at baseline were strong predictors of hypertension. Before the age of 50 years, male sex and a fast heart rate were also forerunners of hypertension. Conclusions The stepwise increase in incidence of hypertension across the three non-hypertensive blood pressure categories in our cohort was similar to that observed in the Framingham Heart Study. The Framingham findings, which have informed several guidelines, can be extrapolated to a Western European population.