Hospitalization Risk among Older Adults with Chronic Kidney Disease

Abstract

Introduction: Chronic kidney disease (CKD) risk staging is based on estimated glomerular filtration rate (eGFR) and albumin-creatinine ratio (ACR). However, the relationship between all-cause hospitalization risk and the current CKD staging system has not been well studied among older adults, despite a high prevalence of CKD and a high risk of hospitalization in old age.

Methods: Among 4,766 participants of the Atherosclerosis Risk in Communities study, CKD was staged according to Kidney Disease Improving Global Outcomes (KDIGO) criteria, using creatinine-based eGFR (eGFRcr) and ACR. Incidence rates of all-cause hospitalization associated with each CKD risk group were analyzed using negative binomial regression. Additionally, cause-specific hospitalization risks for cardiovascular, infectious, kidney, and other diseases were estimated. The impacts of using cystatin C-based eGFR (eGFRcys) to estimate the prevalence of CKD and risks of hospitalization were also quantified.

Results: Participants experienced 5,548 hospitalizations and 29% had CKD. Hospitalization rates per 1,000 person-years according to KDIGO risk categories were 208-223 ("low risk"), 288-376 ("moderately increased risk"), 363-548 ("high risk"), and 499-1083 ("very high risk"). The increased risk associated with low eGFR and high ACR persisted in adjusted analyses, examinations of cause-specific hospitalizations, and when CKD was staged by eGFRcys or eGFRcr-cys, a combined equation based on both creatinine and cystatin C. In comparison to eGFRcr, staging by eGFRcys increased the prevalence of CKD to 50%, but hospitalization risks remained similarly high.

Discussion/conclusion: In older adults, decreased eGFR, increased ACR, and KDIGO risk stages based on a combination of these measures, were strong risk factors for hospitalization. These relationships were consistent, regardless of the marker used to estimate GFR, but the use of cystatin C resulted in a substantially higher prevalence of CKD than the use of creatinine. Older adults in the population with very high risk stages of CKD have hospitalization rates exceeding 500 per 1,000 person-years.

Keywords: Aging; Albuminuria; Chronic kidney disease; Estimated glomerular filtration rate; Hospitalization.

Figure 1.. Risk of Hospitalizations by Estimated Glomerular Filtration Rate and Albuminuria.

Estimates for eGFRcr are shown. Colors indicate risk groups (green: low risk; yellow: moderately increased risk; orange: high risk; red: very high risk) as defined by KDIGO 2012 criteria. *Incidence rate ratios adjusted for age, sex, race-center, diabetes, smoking status, hypertension, and history of cancer, heart failure, coronary heart disease, and stroke. **Omitted due to underpowered estimation.

Figure 2.. Incidence of All-Cause Hospitalizations by Baseline Estimated Glomerular Filtration Rate.

Density curves show the distributions of the three GFR estimates (eGFRcr in blue, eGFRcys in red, and eGFRcr-cys in purple). Risk curves show the crude (solid) and adjusted (dash) risk ratios of hospitalization by baseline level of eGFR, with the reference point at eGFR 75 mL/min/1.73 m². Risk was adjusted to the mean level of all adjustment variables (76 years, female, white, recruited from Minneapolis, BMI of 29, non-diabetic, former smoker, hypertensive, ACR<30 mg/g, no history of heart failure, coronary heart disease, stroke, or cancer).