Synergistic interaction of hypertension and diabetes on chronic kidney disease: Insights from the National Health and Nutrition Examination Survey 1999-2006

Background: Hypertension and diabetes mellitus are 2 major risk factors for chronic kidney disease (CKD). However, whether hypertension and diabetes have a synergistic interaction towards greater renal damage remains unclear. Our study aimed to investigate whether hypertension and diabetes act synergistically towards CKD. Methods: 13,693 subjects from the cross-sectional National Health and Nutritional Examination Survey 1999-2006 were included in our analyses. The associations were investigated by multivariate logistic regression models. The interaction was evaluated on both additive and multiplicative scale. Results: The prevalence of CKD was 17.62%. After adjustment, subjects with both hypertension and diabetes had a 4.710 (3.652-6.073) times risk of CKD than non-hypertensive non-diabetic subjects, higher than that of subjects with only hypertension or diabetes (1.732, 95% CI: 1.502-1.997 and 2.407, 95% CI: 1.815-3.194, respectively). Furthermore, significant interaction was observed between hypertension and diabetes towards CKD in the additive scale (relative excess risk due to interaction: 1.570, 95% CI: 0.507-2.633; the attributable proportion due to interaction: 0.333, 95% CI: 0.168-0.499; Synergy index: 1.734, 95% CI: 1.239-2.426). Additionally, analyses of the associations with components of the primary endpoint demonstrated that the interaction was also applicable to those with reduced eGFR, albuminuria or normoalbuminuric CKD. Conclusions: The joint effect of hypertension and diabetes was significantly larger than the sum of their independent impact on CKD. Our findings may provide intuitionistic and straightforward illustrations for the public to understand the danger of combined hypertension and diabetes on the renal injury. (C) 2019 Elsevier Inc. All rights reserved.