LAUSR

Objective: The prevalence of hypertension in young adulthood, as well as the clinical characteristics associated with different hypertension subtypes, have been inconsistently described. Our aim was to assess the prevalence, time-trends and characteristics associated with isolated systolic hypertension (ISH), isolated diastolic hypertension and combined systodiastolic hypertension. Methods: Serial cross-sectional analysis, using data from the Swedish conscription registry, including 1701 314 (99.2% male) individuals from 1969 to 2010. Risk factor associations were assessed through multivariable logistic regression. Results: The prevalence of hypertension increased progressively during the study period, from 20.4% in 1969 to 29.3% in 2010, with ISH being the most common subtype (94.3%). ISH was associated with elevated resting heart rate (odds ratio 1.85, 95% confidence interval 1.84–1.86, per SD), increased exercise capacity (1.37, 1.36–1.39) and increased BMI (1.30, 1.29–1.31). Isolated diastolic hypertension and combined hypertension were also associated with elevated resting heart rate (1.37, 1.32–1.41 and 2.05, 1.99–2.11, respectively) and more strongly associated with increased BMI (1.36, 1.33–1.40 and 1.54, 1.51 – 1.58), but inversely associated with exercise capacity (0.79, 0.75–0.83 and 0.90, 0.86–0.95). Conclusion: The prevalence of hypertension in young adulthood has increased substantially over time, predominantly due to an increase in ISH. Risk factor patterns differed between ISH and other forms of hypertension, suggesting potentially different underlying mechanisms.