Hematocrit and hypertension incidence: the Gubbio study

High hematocrit is cross-sectionally associated with hypertension. Aim of the study is to investigate this relationship prospectively. Data collected in the Gubbio Population Study at baseline and 6-year follow-up were analyzed. The cohort is 1,670 persons seen at both visits, non-hypertensive at baseline, with hematocrit (HTC) measurement, and baseline ages 18-74 years. At both visits, hypertension was defined as SBP ≥ 140 mm Hg, or DBP ≥ 90 mm Hg, or antihypertensive treatment. Baseline and follow-up HTC were positively related (r=0.630 in men, R=0.530 in women, p<0.001). At follow-up HTC was higher than at baseline in women (p<0.001).not in men. HTC change per year of follow-up was inversely related to baseline HTC in men and women (r=−0.437 and −0.512, p<0.001). Compared to individuals non-hypertensive at baseline and follow-up (N), men and women who developed hypertension after baseline visit (H) had higher baseline HTC without or with inclusion of persons on antihypertensive treatment (p<0.05). HTC change from baseline was not significantly different between N and H without or with inclusion of persons on antihypertensive treatment. A sex-, and age-controlled score of baseline HTC (Low: < median, High: ≥ median) was directly related to hypertension incidence independent of baseline body mass index, alcohol intake, and urinary Na/K (p<0.02). The data are consistent with the concept that high HTC is an independent risk factor for hypertension.