Association of chronic kidney disease with outcomes in chronic heart failure: a propensity-matched study

Background. Chronic kidney disease (CKD) is associated with increased mortality in patients with heart failure (HF). However, its association with hospitalization in HF patients has not been well studied. Methods. Of 7788 patients in the Digitalis Investigation Group trial, 3527 had CKD, defined by an estimated glomerular filtration rate (GFR) < 60 ml/min/1.73 m(2) body surface area (BSA). Propensity scores for CKD were calculated using a multivariable logistic regression model and used to match 2399 pairs of patients with and without CKD. Matched Cox regression analyses were used to estimate association of CKD with outcomes. Results. All-cause hospitalization occurred in 1636 (rate, 4233/10 000 person-years) and 1587 (rate, 3733/10 000 person-years) patients respectively, with and without CKD (matched hazard ratio [HR] for CKD, 1.18, 95% confidence interval [CI], 1.08-1.29; P < 0.0001). Matched HR for cardiovascular and HF hospitalization were respectively 1.17 (95% CI, 1.06-1.28, P = 0.002) and 1.28 (95% CI, 1.13-1.45, P < 0.0001). Compared to GFR >= 60 ml/min/1.73 m(2) BSA, HR for all-cause hospitalization for GFR 45-59 and < 45 ml/min/1.73 m(2) BSA were respectively 1.04 (95% CI, 0.94-1.16; P = 0.422) and 1.58 (95% CI, 1.34-1.87; P < 0.0001). Similarly, HR for all-cause death for GFR 45-59 and < 45 ml/min/1.73 m(2) BSA were respectively 1.03 (95% CI, 0.90-1.18; P = 0.651) and 1.70 (95% CI, 1.40-2.07; P < 0.0001). Matched HR for death due to cardiovascular causes and progressive HF were respectively 1.24 (95% CI, 1.09-1.40; P = 0.001) and 1.42 (95% CI, 1.16-1.72; P = 0.001). Conclusion. CKD was associated with increased mortality and hospitalization in ambulatory patients with chronic HF, which increased progressively with worsening kidney function.