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.