Elderly patients with chronic kidney disease: outcomes after 5 years of follow-up.

INTRODUCTION: In recent years, chronic kidney disease (CKD) has come to be considered an epidemic problem, and there is considerable interest in early diagnosis in order to slow its progression to end-stage renal disease (ESRD) and prepare patients for dialysis and transplantation programmes. Many elderly patients are labelled as having CKD based solely on having a glomerular filtration rate (GFR) of <60 ml/min.

OBJECTIVE: Monitor renal function (RF) and outcomes associated with CKD (morbidity, mortality and progress to ESRD) in an elderly cohort.

PATIENTS AND METHOD: A total of 80 clinically stable patients, with a median age of 83 years (range 69-97; 69% female, 35% diabetic, 83% hypertensive) were recruited at random in our Geriatric Medicine and Nephrology Departments between January and April 2006, and monitored for 5 years. During the recruitment stage we established two groups based on baseline serum creatinine (SCr) concentration: Group 1, 38 patients with SCr <1.1mg/dl (range 0.7-1.1) and Group 2, 42 patients with SCr >1.1mg/dl (range 1.2-3). We determined baseline blood levels of creatinine and urea, calculated eGFR using an abbreviated Modification of Diet in Renal Disease (MDRD) formula, and repeated these measurements after 5 years. We recorded baseline comorbidity according to the Charlson comorbidity index (CCI); hospital admissions; new cardiovascular events; treatments; progression to ESRD requiring dialysis; and mortality.

RESULTS: In the 39 patients surviving after 5 years there were no significant differences between Groups 1 and 2 in total number of hospital admissions, episodes of heart failure and new ischaemic heart disease. Overall, the most commonly used drugs were diuretics (76.9%), while beta-blockers were used the least (10.3%). There were 41 deaths (51.3%): of these patients, 15 died due to overall decline, 8 due to infections, 4 due to stroke, 4 due to neoplasia, 3 due to cardiovascular problems, 2 due to complications from fractures and 5 due to unknown causes. Mortality was higher in Group 2 (66.7% vs 34.2%, P=.004) and patient age was also higher in that group (84.73 ± 5.69 vs 80.12 ± 6.5, P=.001). No significant differences in mortality were attributable to sex, diabetes, hypertension or CCI. Only 2 patients in Group 2 progressed to ESRD, they received conservative treatment due to comorbidity (no patients in the study have started dialysis). The evolution of RF (baseline/5 years) in all patients surviving at 5 years was as follows: SCr (mg/dl): 1.15 ± 0.41/1.21 ± 0.49 (not significant [NS]), urea (mg/dl) 52.21 ± 13.0/61.21 ± 27.0 (P=.047), MDRD (ml/min/1.73m2) 57.47 ± 15/54.86 ± 17 (NS). There were no differences in progression between the 2 groups. In the logistic regression analysis for overall mortality (independent variables: age, sex, CCI, cardiovascular history, SCr and group), only age (relative risk [RR]: 1.12; 1.03-1.23, P=.009) and group (RR: 3.06; 1.10-8.40, P=.031) were independently associated with mortality.

CONCLUSION: Screening for CKD using GFR only may lack clinical relevance in this population since RF slowly deteriorates in elderly patients without proteinuria. Mortality due to all causes was higher in elderly patients with a poorer baseline RF, and mortality rates were higher than rates of CKD progression to ESRD.