Disentangling the Impact of Chronic Kidney Disease, Anemia, and Mobility Limitation on Mortality in Older Patients Discharged From Hospital

Abstract

Backgrounds: Chronic kidney disease (CKD), anemia, and mobility limitation are important predictors of mortality. We aimed at investigating the interactions between estimated glomerular filtration rate (eGFR), anemia, and physical performance on 1-year mortality in older patients discharged from acute care hospitals.

Methods: Four hundred and eighty seven patients enrolled in a multicenter, prospective observational study were included in the analysis. eGFR was estimated by the Berlin Initiative Study 1 equation. Anemia was defined on the basis of hemoglobin values. Mobility limitation was rated by the Short Physical Performance Battery (SPPB). Covariates included demographics, nutritional status, cognitive performance, and comorbidity. The outcome of the study was mortality over 1-year follow-up. Interactions among study variables were investigated by survival tree analysis.

Results: eGFR < 30 mL/min/1.73 m(2), anemia, and SPPB = 0-4 were significantly associated with mortality, as were hypoalbuminemia and cognitive impairment. Survival tree analysis showed that compared to patients with SPPB ≥ 4 and eGFR ≥ 46.7 mL/min/1.73 m(2) (ie, patients with the least mortality), patients with SPPB < 4 and hemoglobin < 12.2 g/dL had the highest risk of mortality [hazard ratio (HR) = 28.9, 95%CI 10.3-81.2]. Patients with SPPB ≥ 4 and eGFR < 46.7 mL/min/1.73 m(2) and those with SPPB > 4, hemoglobin ≥ 12.2g/dL, and eGFR ≥ 58.6 mL/min/1.73 m(2) had intermediate risk (HR = 6.58, 95%CI = 2.15-20.2, and HR = 15.11, 95%CI=4.42-51.7, respectively). Having SPPB < 4, hemoglobin ≥ 12.2 g/dL, and eGFR<58.6 mL/min/l.73 m(2) was not significantly associated with increased mortality (HR = 2.95, 95%CI = 0.74-11.8).

Conclusions: Interactions among eGFR, anemia, and mobility limitation define different profiles of risk in older patients discharged from acute care hospitals, which deserve to be considered to identify patients needing special care and careful follow-up after discharge.

Keywords: 1-year mortality; Anemia; Estimated glomerular filtration rate; Mobility limitation; Net reclassification improvement.; Short physical performance battery; Survival tree analysis.