CKD and Hospitalization in the Elderly: A Community-Based Cohort Study in the United Kingdom

Background: We previously have shown that chronic kidney disease (CKD) is associated with cardiovascular and all-cause mortality in community-dwelling people 75 years and older. The present study addresses the hypothesis that CKD is associated with a higher rate of hospital admission at an older age. Study Design: Cohort study. Setting & Participants: 15,336 participants from 53 UK general practices underwent comprehensive health assessment between 1994 and 1999. Predictor: Data for estimated glomerular filtration rate (eGFR, derived from creatinine levels using the CKD Epidemiology Collaboration [CKD-EPI] study equation) and dipstick proteinuria were available for 12,371 participants. Outcomes: Hospital admissions collected from hospital discharge letters for 2 years after assessment. Measurements: Age, sex, cardiovascular risk factors, possible biochemical and health consequences of kidney disease (hemoglobin, phosphate, and albumin levels; physical and mental health problems). Results: 2,310 (17%) participants had 1 hospital admission, and 981 (7%) had 2 or more. After adjusting for age, sex, and cardiovascular risk factors, HRs were 1.66 (95% CI, 1.21-2.27), 1.17 (95% CI, 0.95-1.43), 1.08 (95% CI, 0.90-1.30), and 1.11 (95% CI, 0.91-1.35) for eGFRs <30, 30-44, 45-59, and >= 75 mL/min/1.73 m(2), respectively, compared with eGFRs of 60-74 mL/min/1.73 m(2) for hospitalizations during <6 months of follow-up. HRs were weaker for follow-up of 6-18 months. Dipstick-positive proteinuria was associated with an increased HR throughout follow-up (HR, 1.29 [95% CI, 1.11-1.49], adjusting for cardiovascular risk factors). Dipstick-positive proteinuria and eGFR <30 mL/min/1.73 m(2) were independently associated with 2 or more hospital admissions during the 2-year follow-up. Adjustment for other health factors and laboratory measurements attenuated the effect of eGFR, but not the effect of proteinuria. Limitations: Follow-up limited to 2 years, selection bias due to nonparticipation in study, missing data for potential covariates, and single noncalibrated measurements from multiple laboratories. Conclusions: The study indicates that community-dwelling older people who have dipstick-positive proteinuria and/or eGFR <30 mL/min/1.73 m(2) are at increased risk of hospitalization. Am J Kidney Dis. 57(5): 664-672. (C) 2011 by the National Kidney Foundation, Inc.