Influence of pre-hypertension on all-cause and cardiovascular mortality: The Singapore Cardiovascular Cohort Study

Abstract

Background The effect of “pre-hypertension” (pre-HTN) itself, and in combination with other cardiovascular disease (CVD) risk factors in relation to mortality has not been assessed in Asian populations. Methods From three cross-sectional studies conducted in Singapore (baseline 1982–1995), 5830 persons were grouped into normotensive (NT), pre-HTN or hypertensive (HTN). Follow-up (median 12.0 yrs, IQR 12–19 yrs) was done by linkage to the National Death Register. Outcomes included all-cause and CVD (ischaemic heart disease (ICD-9 410–414) and cerebrovascular accidents (ICD-9 430–438)). Cox's proportional hazards model was used to obtain adjusted hazard ratios (HRs) for risk of mortality. Results After adjustment, pre-HTN was not associated with a statistically significant increased risk of all-cause or CVD mortality. However, an increased risk for all-cause and CVD mortality, in the presence of diabetes (adjusted HR 1.8; 95%CI 1.0–2.9 and 4.4; 95%CI 1.9–10.4), smoking (adjusted HR 2.2; 95%CI 1.3–3.5 and 4.9; 95%CI 1.8–13.3), and especially, pre-existing CVD (adjusted HR 3.1; 95%CI 1.5–6.4 and 9.3; 95%CI 3.3–25.9) was found. Conclusions Pre-HTN was not an independent risk factor for mortality. However an increased risk of mortality for pre-HTN in the presence of other CVD risk factors was observed. This finding supports current recommendations to screen for these risk factors in the pre-HTN Asian population.