Association between kidney function, rehabilitation outcome, and survival in older patients discharged from inpatient rehabilitation

Abstract

Background: Chronic kidney disease (CKD) is common in older people, but it is unclear if it affects survival and rehabilitation outcomes independent of comorbid conditions and physical function in this population.

Study design: Cohort analysis of prospective, routinely collected, linked clinical data sets.

Setting & participants: Patients discharged from a single inpatient geriatric rehabilitation center over a 12-year period.

Predictors: Admission estimated glomerular filtration rate (eGFR) category as a predictor of improvement in the 20-point Barthel score (activities of daily living measure) during rehabilitation; discharge eGFR category and Barthel score as predictors of survival postdischarge.

Outcomes: Survival postdischarge was modeled using Cox regression analyses, unadjusted and adjusted for age, sex, morbidities (ischemic heart disease, chronic obstructive pulmonary disease, stroke, diabetes, and heart failure), Barthel score and eGFR category on discharge, and serum calcium, hemoglobin, and albumin levels. The effect of admission eGFR category on change in Barthel score during admission was modeled using analysis of covariance, adjusted for admission, Barthel score, and comorbid conditions.

Results: 3,012 patients were included; mean age, 84 years. 2,394 patients died during a mean follow-up of 8.3 years. Compared with patients with eGFR of 60 to 89mL/min/1.73m(2), adjusted HRs for death were 1.26 (95% CI, 1.13-1.40), 1.45 (95% CI, 1.29-1.63), and 1.68 (95% CI, 1.42-1.99) for eGFR categories of 45 to 59, 30 to 44, and <30mL/min/1.73m(2), respectively. The relationship between discharge Barthel score and survival was similar within each discharge eGFR category (HRs of 0.95, 0.93, 0.92, 0.95, and 0.90 per Barthel score point within eGFR categories of ≥90, 60-89, 45-59, 30-44, and <30mL/min/1.73m(2); P for interaction = 0.2). Similar improvements in Barthel score between admission and discharge were seen for each admission eGFR category.

Limitations: Single-center study using routinely collected clinical data.

Conclusions: eGFR category and Barthel score are independent risk markers for survival in older rehabilitation patients, but advanced CKD does not preclude successful rehabilitation.

Keywords: Barthel score; Chronic kidney disease (CKD); activities of daily living (ADLs); frailty; functional impairment; geriatric; mortality; older adults; oldest old; physical function; reduced renal function; rehabilitation.