The 10-year incidence of hypertension across blood pressure categories in a population-based cohort in southwestern Sweden

BACKGROUND: To explore the determinants of incident hypertension, and especially the impact of baseline blood pressure categories, in a representative Swedish population. METHODS: A 10-year longitudinal study of residents aged 30-74. Blood pressures were measured and categorized according to ESH guidelines with optimal blood pressure < 120/80 mmHg, normal 120-129/80-84 mmHg, and high normal 130-139/85-89 mmHg. Incident hypertension was defined as ongoing treatment or three consecutive blood pressure readings ≥ 140/ ≥ 90 mmHg (one or both) at follow-up, while those with ≥ 140 and/or ≥ 90 mmHg at only one or two visits were labelled as unstable. After excluding subjects with hypertension, ongoing blood pressure lowering medication or a previous CVD event at baseline, 1099 remained for further analyses. RESULTS: Sixteen (2.6%) subjects with optimal baseline blood pressure had hypertension at follow up. Corresponding numbers for subjects with normal, high normal and unstable blood pressure were 55 (19.4%), 50 (39.1%) and 46 (74.2%), respectively. Compared with subjects in optimal group those in normal, high normal and unstable blood pressure categories had significantly higher risk to develop manifest hypertension with odds ratios OR and (95% CI) of 7.04 (3.89-12.7), 17.1 (8.88-33.0) and 84.2 (37.4-190), respectively, with adjustment for age, BMI and family history for hypertension. The progression to hypertension was also independently predicted by BMI (p < 0.001), however, not by age. CONCLUSIONS: Subjects with high normal or unstable blood pressure should be identified in clinical practice, evaluated for global hypertension risk and offered personalized advice on lifestyle modification for early prevention of manifest hypertension and cardiovascular disease.