Interaction effect of blood glucose and pressure on the risk of chronic kidney disease: a population-based prospective cohort study

Objective: To evaluate the interaction effect of blood glucose and blood pressure on the risk of chronic kidney disease (CKD). Methods: 31,165 subjects were selected without CKD at baseline and had completed the first follow-up from "Jinchang cohort". Cox regression model and restricted cubic splines functions were used to evaluate the effects of blood glucose or pressure on the incidence of CKD and dose-response relationship after adjusting for confounding covariates. Synergic effect was assessed by the multiplicative or additive interaction scale. Results: Among 31,165 subjects, 1307 new-onset CKD were observed during 68905.78 person-years follow-up, and the incidence density was 18.97 per 1000 person-years. The risk of CKD gradually increased with the increase of blood pressure in diabetes, pre-diabetes and normal groups (P-trend < 0.05). And, the risk was greatest when SBP/DBP reached >= 150/>= 110 mmHg in three groups, and HRs (95% CI) were 1.610 (1.070-2.422), 2.142 (1.396-3.288) and 2.455 (1.941-3.106), respectively. Additionally, among hypertension, pre-hypertension and normal groups, the risk of CKD increased by 16.0%, 14.3% and 25.2% for each 1 mmol/L of FPG. When FPG level was more than 9.0 mmol/L, the risk was greatest and adjusted HRs (95% CI) were 2.856 (2.176-3.748), 2.979 (1.828-4.854) and 7.520 (4.517-12.519). Furthermore, the risk was highest when hypertension was accompanied by diabetes (HR = 4.915, 95% CI: 3.923-6.157). This analysis supported a less than multiplicative effect (HR = 0.634, 95% CI: 0.417-0.964) for the interaction term of diabetes and hypertension, while there was no additive interaction towards CKD in all interaction term. Conclusions: Blood glucose and pressure were independent risk factors in incidence of CKD, but there was only a negative multiplicative interaction between hypertension and diabetes, but no additive interaction effect between them.