Pre-hypertension as a significant predictor of chronic kidney disease in a general population: The Ohasama Study

Background. Hypertension is associated with an increased risk of development of chronic kidney disease (CKD). However, it is unclear whether pre-hypertension is related to the incidence of CKD. Methods. The incidence of CKD defined as positive proteinuria or estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m² was examined in 2150 inhabitants without pre-existing CKD from the general Japanese population. The association of blood pressure and CKD incidence was examined using a Cox regression model adjusted for age, sex, habitual smoking and drinking, obesity, history of cardiovascular disease, diabetes mellitus or hypercholesterolemia, eGFR at baseline, number of follow-up examinations and year of baseline examination. Participants were categorized according to the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure. Results. Participants were categorized into normotension (n 586, 27.3 ), pre-hypertension (n 815, 37.9 ), Stage 1 hypertension (n 386, 18.0 ) and Stage 2 hypertension (n 363, 16.9 ). During a mean follow-up of 6.5 years (14 023 person-years), 461 incidences of CKD were recorded. Compared to normotension, adjusted hazard ratios of CKD were significantly higher for pre-hypertension (1.49, P < 0.003), Stage 1 (1.83, P < 0.001) and Stage 2 (2.55, P < 0.001) hypertension. The population-attributable fraction of pre-hypertension (12.1 ) was considered to be compatible to that of Stage 1 (8.6 ) and Stage 2 (14.9 ) hypertension. Conclusion. This was the first study to demonstrate that pre-hypertension was significantly associated with an increased risk of CKD and was one of the considerable causes of CKD in the general population.