Background Chronic kidney disease (CKD) is a serious risk to the health and longevity of the elderly, and hypertension is closely related to CKD. However, the studies on the correlation of blood pressure levels with the development and progression of CKD in older adults have shown inconsistent results.
Objective To explore the association between blood pressure levels and the risk of CKD among the elderly in longevity areas of China.
Methods From October 2021 to May 2022, a total of 989 older adults who underwent physical examination with biomedical indicators collected in 2012 were selected as subjects based on the subcohort of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) -Healthy Aging and Biomarkers Cohort Study (HABCS) . Age, gender, height, weight, blood pressure, blood lipid, blood glucose, routine blood and urine indicators were collected at baseline, and follow-up monitoring was conducted in 2014. Cox proportional hazards regression model was used to analyze the association between the blood pressure levels and the risk of CKD.
Results A total of 989 subjects were included in the study, with a median age of 79 (70, 88) years. The cumulative follow-up were 2 046 person-years, with an average follow-up time of (2.07±0.50) years. There were 183 new cases of CKD, the cumulative incidence of CKD was 18.5%〔95%CI (16.1%, 21.1%) 〕, and the incidence density was 89.4/1 000 person-years. During the follow-up, 9.8% (10/102) , 14.0% (47/335) and 22.8% (126/552) of the older adults in the normal blood pressure, high normal blood pressure and hypertension groups developed CKD, respectively, and the difference was statistically significant among the three groups (χ2=16.40, P<0.001) . The results of Cox regression showed that after adjusting for age, sex, BMI, waist circumference, calf circumference, fasting blood glucose, glycosylated serum protein, total cholesterol, triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, uric acid, superoxide dismutase, vitamind3, white blood cell count, red blood cell count, platelet count, blood urea nitrogen and history of diabetes, the older adults in the hypertension group had a higher risk of CKD〔HR (95%CI) =2.28 (1.13, 4.60) 〕 than those in the normal blood pressure group; the risk of CKD was 1.83 times〔95%CI (1.02, 3.29) 〕 higher in the older adults with baseline SBP≥140 mmHg (1 mmHg=0.133 kPa) than those with baseline SBP<120 mmHg, and the risk of CKD was 1.55 times〔95%CI (1.02, 2.35) 〕 higher in the older adults with baseline DBP≥90 mmHg than those with baseline DBP<80 mmHg (P<0.05) .
Conclusion Hypertension is an independent risk factor for CKD in the elderly. It is particularly important to increase screening and prevention of CKD in older adults with predominantly elevated systolic blood pressure.