Prehypertension and risk for all-cause and cardiovascular mortality by diabetes status: results from the national health and nutrition examination surveys

Background: It is unclear whether prehypertension alone or combined with diabetes associate with a higher risk for cardiovascular or all-cause mortality. The purpose of this study was to explore the relationship between prehypertension and all-cause and cardiovascular mortality stratified by diabetes status.

Methods: All participants aged ≥18 years were enrolled from the 1999-2014 National Health and Nutrition Examination Surveys (NHANES). Prehypertension was defined as systolic/diastolic blood pressure (BP): 120-139/80-89 mmHg. The status of cardiovascular and all-cause mortality of participants were followed up through 31 December 2015. We performed Cox proportional hazards models and Kaplan-Meier survival curves to evaluate the relationships as mentioned above.

Results: In general, we enrolled 26,070 participants while 15,295 (58.67%) of them did not have diabetes nor prehypertension, 8,870 (34.02%) had prehypertension alone, 835 (3.20%) had diabetes alone, and 1,070 (4.11%) had both diabetes and prehypertension. Compared with participants without diabetes nor prehypertension, the multivariable adjusted hazard ratios and 95% confidence interval (CI) for all-cause mortality among participants with prehypertension alone, diabetes alone, and both diabetes and prehypertension were 1.08 (95% CI: 0.95, 1.23), 1.26 (0.98, 1.62), and 1.67 (1.38, 2.03) (P for trend <0.001), for cardiovascular mortality, the corresponding hazard ratios and 95% CI were 1.40 (95% CI: 0.92, 2.14), 2.21 (1.12, 4.38), and 2.87 (1.65, 4.99) (P for trend <0.001) respectively.

Conclusions: Our findings suggested that prehypertension associated with an increased risk for cardiovascular and all-cause mortality when compared with diabetes, but not for prehypertension alone. Early screening and intervention for BP among diabetic patients may be beneficial.