Objective: Prehypertension is a known risk factor for hypertension in individuals aged less than 20 or more than 35 years, but no large studies have investigated this risk in individuals aged 20–34 years. This study investigated progression to hypertension in nonhypertensive individuals aged 20–34 years and compared this group with individuals aged 35–64 years.
Methods: A total of 12 639 nonhypertensive individuals aged 20–64 years were followed from 1999 to 2008. Hazard ratios for progression to hypertension were calculated for men and women according to three blood pressure (BP) categories (optimal BP: <120/80 mmHg; normal BP: 120–129/80–84 mmHg; high-normal BP: 130–139/85–89 mmHg) and three age groups (20–34, 35–49 and 50–64 years).
Results: Progression to hypertension occurred in 4617 individuals (36.5%). The risk of progression to hypertension increased significantly with increasing baseline BP category in men and women in all age groups. The association between baseline BP and progression to hypertension was stronger in the group aged 20–34 years than in the older age groups, especially in men.
Conclusion: The results of this study confirm that normal or high-normal BP increases the risk of progression to hypertension in individuals aged 20–34 years. In men, the association between baseline BP and progression to hypertension is stronger in this age group than in older age groups. Health providers should be aware that normal or high-normal BP is a risk factor for progression to hypertension even in individuals aged 20–34 years.