Interaction between the stage of chronic kidney disease and diabetes mellitus as factors associated with mortality in chronic kidney disease patients: An external cohort study.

Introduction: Diabetic kidney disease is the main cause of chronic kidney disease (CKD) worldwide. Both CKD and diabetes mellitus (DMT2) are important risk factors for mortality. However, it is still unknown if the risk of death is modified by the simultaneous presence of these diseases.

Objective: To evaluate the presence of an interaction between DMT2 and CKD for mortality in a representative population of a Latin American country.

Methods: It is an analytical cohort study of patients with CKD, who were followed for 4 years (between 2004 and 2009). We calculated the incidence rate, progression, survival (using Kaplan-Meier curves), interaction (on the additive and multiplicative scales) and impact of the different stages of CKD in patients with and without DMT2 (using a cox proportional hazards model).

Results: In this population of 5663 individuals, both DMT2 and CKD are risk factors for mortality (P < 0.001). We found a statistically significant difference in mortality between individuals with and without DMT2, who also had CKD stages 3 - 4 - 5 (Log-rank P = 0.0076). Additionally, we found a statistically significant interaction for mortality in both the additive and multiplicative scales between DMT2 and CKD (P = 0.005). DMT2 was found to be a risk factor for mortality (Hazard Ratio 1.61 P < 0.001), but in individuals with DMT2, the only risks significantly associated with mortality, were age, dyslipidemia and nephroprotective drugs. CONCLUSIóN: The interaction between CKD and DMT2 negatively modifies the risk of death of both diseases. This means that when the two diseases are present, the risk of mortality is lower than expected.