Sex Differences in Relative Contributions of Hemodynamic Parameters to Blood Pressure: A Population-based Study of Adolescents and Middle-aged Adults

Hypertension is a leading cause of death. Sex differences in blood pressure (BP) and hypertension prevalence emerge during adolescence and remain throughout reproductive age. Sex differences in BP-underlying hemodynamics, i.e., in the relative contributions of stroke volume (SV), total peripheral resistance (TPR) and heart rate (HR) to BP, have not been investigated in these age categories in a population-based setting. We studied a cohort of 1,347 individuals, including 911 adolescents (12-18 years, 52 % female) and 426 young to middle-aged adults (36-65 years, 56 % female). Beat-by-beat systolic BP (SBP) and diastolic BP (DBP), together with HR, SV, and TPR, were measured with a Finometer throughout a 52-min protocol; the protocol was intended to “mimic” daily-life activities, such as changes in posture and mental stress. It is well established that BP during regular daily activities (ambulatory BP monitoring) is a better predictor of target-organ damage than standard office BP. The relative contributions of HR, SV and TPR to SBP and DBP were determined by decomposing the model-explained variance into non-negative contributions. The relative contributions of SV, TPR and HR to SBP and DBP showed marked sex differences in young and middle-aged adults. The main determinant of higher SBP was SV in females (55 [50-60] % in females vs. only 35 [30-40] % in males), whereas it was TPR in males (47 [41-52] % in males vs. only 30 [26-34] % in females). The main determinant of higher DBP was TPR in both sexes, but its contribution was higher in males than females (58 [52-63] % vs. 41 [36-45] %, respectively). These sex differences were seen across most of the 52-min protocol, being most prominent during standing and least evident during mental stress. Similar sex differences were observed in adolescents, but they were less pronounced, being significant only during standing. The present population-based study of adolescents and young to middle-aged adults, suggest that marked sex differences exist in BP-underlying hemodynamics, with BP being driven mainly by SV in females and by TPR in males. These results underscore the need for sex-specific treatments of hypertension (not recommended currently), which affects 3-5 % of adolescents and 23-58% of young to middle-aged adults.