Chronic Kidney Disease in the Elderly: Evaluation and Management
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Review For reprint orders, please contact: [email protected] 11 Review Chronic kidney disease in the elderly: evaluation and management Clin. Pract. Chronic kidney disease (CKD) is a very common clinical problem in elderly patients Mary Mallappallil1, Eli A and is associated with increased morbidity and mortality. As life expectancy continues Friedman1, Barbara G to improve worldwide, there is a rising prevalence of comorbidities and risk factors Delano1, Samy I McFarlane2 ,1 such as hypertension and diabetes predisposing to a high burden of CKD in this & Moro O Salifu* 1Division of Nephrology, SUNY population. The body of knowledge on the approach to elderly patient with CKD Downstate Medical Center, Brooklyn, is still evolving. Thus, this review seeks to explore the epidemiology and to discuss NY 11203, USA current understanding of challenges in the diagnosis and management of elderly 2Department of Endocrinology, SUNY patients CKD. Downstate Medical Center, Brooklyn, NY 11203, USA Keywords: chronic kidney disease • CKD • elderly • GFR • MDRD • old age • risk *Author for correspondence: factors • US Tel.: +1 718 270 1584 Fax: +1 718 270 3327 [email protected] Although considerable interest continues elderly with CKD, as of 2005 the Accredi- to mount on diseases of the elderly, there is tation Council for Graduate Medical Edu- no universally accepted definition of elderly cation included geriatric nephrology train- particularly in patients with chronic kidney ing in the core curriculum for nephrology disease (CKD). In 1935, the USA passed the f ellowship [6]. first Social Security Act, using age 65 years as the age of retirement and the age at which a Prevalence of CKD in the elderly person became eligible for government wel- There is a high prevalence of CKD in the fare benefits[1] . Since then, being above 65 elderly. This is attributable mainly to increas- years old is largely accepted as being elderly. ing prevalence of traditional risk factors for The proportion of the US population over CKD such as diabetes, [7] hypertension and the age of 65 years has increased from 4% cardiovascular disease (CVD) as well as due 5 (approximately 3 million in a population of to new definitions that have expanded the 65 million) in 1900, to 12% (35 million in a estimated glomerular filtration rate (eGFR) population of 280 million) in the year 2000 range for CKD. These new definitions for [2]. The proportion of the elderly is predicted CKD are kidney damage evidenced by 2014 to further rise to 20% by the year 2030 [3]. abnormal renal markers or a reduction of the Worldwide the median age of the world’s absolute eGFR to less than 60 ml/min/1.73 population has increased, due to a decline m2 for at least 3 months. Abnormal renal in fertility with fewer births and a 20-year markers are proteinuria, abnormal radiology, increase in the average life span in the sec- abnormal cells in the urine or renal pathol- ond half of the 20th century [4]. Overall the ogy on biopsy. In addition, a history of renal demographic change from a pattern of high transplantation is included in the definition birth rates and high mortality to low birth [8]. These definitions were derived from stud- rates and delayed mortality has contributed ies of the Third National Health and Nutri- to the rise in the elderly population [5]. Given tion Examination Survey data in the United the rise of the aging population, and impli- States. The prevalence of CKD in the US cations on diagnosis and management of the adult population was noted to be 11%. The part of 10.2217/CPR.14.46 © 2014 Future Medicine Ltd Clin. Pract. (2014) 11(5), 525–535 ISSN 2044-9038 525 Review Mallappallil, Friedman, Delano, McFarlane & Salifu prevalence in the US elderly was much higher at about inaccurate 24-h urine collection, patient compliance 39.4% of persons aged 60+ years have been noted with instructions on the collection technique and nor- to have CKD versus 12.6 and 8.5% of persons aged mal variation from day to day [13] . Estimating equa- 40–59 years and 20–39 years, respectively [9]. These tions (Table 2), such as the modification of diet in renal numbers could have been overestimated but are higher disease (MDRD) or CKD-epidemiology (CKD-EPI) than the percentage of people with diabetes alone formulas [14], for their ease of use have now largely (9.3%) or just CVD (8.5%) making CKD a significant replaced creatinine clearance measurement. Software public health problem. for estimating GFR are available on the internet and Based on Medicare (age >65 years) claims data for can be accessed using personal digital assistants. 2011 prevalent US population, CKD was noted to be about 10% in contrast to 1.5% of the younger employed Difficulty of eGFR population [10], suggesting that the elderly carried the Recognizing CKD increasingly as a disease of elderly overall burden of CKD. Indeed, the older one is, the individuals there are concerns that this standardiza- higher the likelihood for CKD. The odds ratio (OR) tion of eGFR has led to an increase in the number of CKD for Medicare patients between ages 75 and of older individuals labeled as having CKD [15] . An 79 is 40% higher (OR: 1.4) than patients 65–74 years. important question that must be addressed is whether In those people over age 80 the OR is 1.75. Men have elderly patients classified as having CKD are done so more CKD than women and African-Americans are based on a single reduced eGFR value without other also much more likely to have CKD than whites. evidence of kidney damage [16] . The difficulty in Claims data give us the number of CKD people ascer- calculating the eGFR in the elderly is further com- tained by medical personnel. Because CKD is largely pounded by the various equations that can be used a silent disease, many people will meet the technical while there is conflicting data about which one is criteria but not be observed in the clinic setting and best. Ferhman and others used the iohexol clearance therefore these claims data may u nderestimate CKD to determine GFR and compared the results to esti- prevalence. mating equations in normal elderly subjects between the ages 70 and 110 years, and found that the GFR Classification of CKD had a strong correlation with age (p = 0.0002), with Based on new definition of CKD noted above[11] , an annual decline of 1.05 ml/min [17] . In addition, guidelines were developed that classify kidney disease they found that using the MDRD formula performed into five stages, from kidney disease with a preserved better in the elderly while Cockroft–Gault, underes- GFR to end-stage kidney failure. In stage 1, there is evi- timated clearance. On the other hand, Dowling and dence of kidney damage but glomerular filtration rate others found that the MDRD and CKD-EPI equa- (GFR) is preserved (>90 ml/min); stage 2 is mild kid- tions significantly overestimated creatinine clearance ney damage with GFR 60–90 ml/min; stage 3 is mod- in elderly individuals, which could lead to dose calcu- erate kidney damage with GFR 30–59 ml/min; stage lation errors for many drugs, particularly in individu- 4 is severe kidney damage with GFR 15–29 ml/min; als with severe renal impairment and suggested that while stage 5 is end-stage renal failure (ESRD) with the Cockcroft Gault equation be used in older adults GFR <15 ml/min. This classification serves as a means for the purpose of renal dosage adjustments [18]. Koppe of alerting health care providers when complications of and others, compared the Berlin Initiative Study (BIS- CKD occur, and to give guidelines as to when to ini- 1) equation that was recently developed to improve tiate various interventions (Table 1) [12] . For instance, the precision and accuracy of GFR estimation in older stage 3 requires initiating management of complica- people and compared it to the simplified MDRD and tions alongside controlling risk factors to retard dis- the CKD-EPI equations in a study of 224 Caucasian ease progression while stage 5 requires that patient patients over the age of 70 years. Simultaneous mea- be a dequately prepared to initiate renal r eplacement surements of plasma creatinine and renal clearance therapy. of inulin were used. They found that BIS-1 was the Accurate determinations of GFR require the use most accurate: the percentage of GFR estimates that of inulin clearance or a radiolabeled compound fell within the range of measured GFR was 75.56% (e.g., iothalamate), which are expensive and not com- compared with 70.67% with MDRD and 72% with monly used. In practice, precise knowledge of the GFR CKD-EPI. In addition BIS-1 had the lowest median is not required, and the disease process usually can be bias and the highest precision. As disease progressed, adequately monitored by obtaining a 24-h urine collec- in people with CKD stages 4 and 5, the CKD-EPI tion for calculation of creatinine clearance. However, equation had the highest accuracy, the lowest median there is a significant variability of test results due to bias and the highest precision. They concluded that 526 Clin. Pract. (2014) 11(5) future science group Chronic kidney disease in the elderly: evaluation & management Review Table 1. Classification and estimated prevalence of chronic kidney disease. Stage GFR status eGFR Intervention (ml/min/1.73 m2) 1 Kidney disease with normal GFR >90 Control comorbidities, slow progression, CVD risk reduction 2 Mildly impaired GFR 60–89 Estimating rate of progression 3 Moderately impaired GFR 30–59 Treat complications 4 Severely impaired GFR 15–29 Preparation for dialysis or transplant 5 Kidney failure <15 Dialysis or transplant The estimates for the prevalence of patients with stages 1–4 are derived using microalbuminuria (stage 1 has 6 million, stage 2 has 5 million, stage 3 has 8 million and stage 4 has 400,000 patients).