Rate of kidney function decline associates with mortality

Abstract

The effect of rate of decline of kidney function on risk for death is not well understood. Using the Department of Veterans Affairs national databases, we retrospectively studied a cohort of 4171 patients who had rheumatoid arthritis and early stage 3 chronic kidney disease (CKD; estimated GFR 45 to 60 ml/min) and followed them longitudinally to characterize predictors of disease progression and the effect of rate of kidney function decline on mortality. After a median of 2.6 years, 1604 (38%) maintained stable kidney function; 426 (10%), 1147 (28%), and 994 (24%) experienced mild, moderate, and severe progression of CKD, respectively (defined as estimated GFR decline of 0 to 1, 1 to 4, and >4 ml/min per yr). Peripheral artery disease predicted moderate progression of CKD progression. Black race, hypertension, diabetes, cardiovascular disease, and peripheral artery disease predicted severe progression of CKD. After a median of 5.7 years, patients with severe progression had a significantly increased risk for mortality (hazard ratio 1.54; 95% confidence interval 1.30 to 1.82) compared with those with mild progression; patients with moderate progression exhibited a similar trend (hazard ratio 1.10; 95% confidence interval 0.98 to 1.30). Our results demonstrate an independent and graded association between the rate of kidney function decline and mortality. Incorporating the rate of decline into the definition of CKD may transform a static definition into a dynamic one that more accurately describes the potential consequences of the disease for an individual.

Figure 1.

Severe kidney function decline associates with higher risk of death in patients who are younger than 74 years and in patients with hypertension. (A) Forest plot of the association of severe CKD progression and the risk for death in subgroups on the basis of age, race, and a number of comorbid conditions. Severe CKD progression was defined as eGFR loss of >4 ml/min per year. HTN, hypertension; DM, diabetes mellitus. *P for interaction was statistically significant for the subgroup on the basis of age (P = 0.0230) and hypertension (P = 0.0337). (B) P values for interaction in the subgroups.

Figure 2.

Flowchart detailing the exclusion and inclusion criteria for the creation of the study cohort. Fiscal year XXXX starts on October 1 of the preceding calendar year (XXXX − 1) until September 30 of the same calendar year (XXXX).