Age-Specific Associations of Reduced Estimated Glomerular Filtration Rate with Concurrent Chronic Kidney Disease Complications

Abstract

SummaryBackground and objectives It has been suggested that moderate reductions in estimated GFR (eGFR) among older adults may not reflect chronic kidney disease (CKD).Design, setting, participants, & measurements We examined age-specific (Ͻ60, 60 to 69, 70 to 79, and Ն80 years) associations between eGFR level and six concurrent CKD complications among 30,528 participants from the National Health and Nutrition Examination Survey (NHANES) 1988(NHANES) to 1994(NHANES) and 1999(NHANES) to 2006 (n ϭ 8242 from NHANES 2003 to 2006 for hyperparathyroidism). Complications included anemia (hemoglobin Ͻ12 g/dl women, Ͻ13.5 g/dl men), acidosis (bicarbonate Ͻ22 mEq/L), hyperphosphatemia (phosphorus Ն4.5 mg/dl), hypoalbuminemia (albumin Ͻ3.5 mg/dl), hyperparathyroidism (intact parathyroid hormone Ն70 pg/ml), and hypertension (systolic/diastolic BP Ն140/90 mmHg or antihypertensive use).Results Among participants Ն80 years old, compared with those with estimated GFR (eGFR) Ն60 ml/min per 1.73 m 2 , the multivariable adjusted prevalence ratios (95% confidence interval) associated with eGFR levels of 45 to 59 and Ͻ45 ml/min per 1.73 m 2 were 1.39 (1.11 to1.73) and 2.06 (1.59 to 2.67) for anemia, 1.33 (0.89 to 1.98) and 2.47 (1.52 to 4.00) for acidosis, 1.11 (0.70 to 1.76) and 2.16 (1.36 to 3.42) for hyperphosphatemia, 2.04 (1.39 to 3.00) and 2.83 (1.76 to 4.53) for hyperparathyroidism and 1.09 (1.03 to 1.14), and 1.12 (1.05 to 1.19) for hypertension, respectively. Higher prevalence ratios for these complications at lower eGFR levels were also present at younger ages. Reduced eGFR was associated with hypoalbuminemia only for adults Ͻ70. ConclusionsReduced eGFR was associated with a higher prevalence of several concurrent CKD complications, regardless of age.

Hemoglobin discriminates stages of chronic kidney disease in elderly patients

“…However, anemia caused by nutritional insufficiency is more common in stages 1 and 2 CKD (18). A positive correlation between the degree of anemia and the degree of kidney insufficiency has been previously reported (19,20). The results of the present study indicated that the level of Hb decreased with decreasing renal function.…”

Age, eGFR, and CKD Complications

“…Thus, the CKD-EPI is not more accurate than the MDRD in elderly patients. In addition, as pointed out by Bowling et al, their study lacked demographic diversity, suggesting that more investigation of ethnically diverse elderly patients with CKD is needed (8).…”

“…Their evaluation of anemia, acidosis, hyperphosphatemia, hypoalbuminemia, and hypertension in more than 30,000 participants in the NHANES data and hyperparathyroidism in more than 8000 participants suggests that reductions in eGFR in elderly patients are not simply age-related declines equating to normal kidney function. Perhaps more importantly, they found that moderate reductions in eGFR (45 to 59 ml/min per 1.73 m 2 ) are associated with anemia, acidosis, hyperparathryoidism, and, more marginally, hyperphosphatemia in those over 80 years of age compared with similarly aged people with eGFR Ͼ60 ml/min per 1.73 m 2 (8). Importantly, elderly patients with eGFR Ͻ45 ml/min per 1.73 m 2 had nearly twice the prevalence ratios of these complications.…”

“…In this issue, Bowling et al extend our understanding of the clinical expression of CKD as defined by eGFR by analyzing NHANES data to examine the prevalence of CKD complications in cohorts of subjects stratified by eGFR (8). Their evaluation of anemia, acidosis, hyperphosphatemia, hypoalbuminemia, and hypertension in more than 30,000 participants in the NHANES data and hyperparathyroidism in more than 8000 participants suggests that reductions in eGFR in elderly patients are not simply age-related declines equating to normal kidney function.…”

“…It is one thing to debate the prevalence of CKD in older adults based on an eGFR that varies by 5 ml/min. It is another thing entirely to consider the potential risk of hip fracture, cognitive impairment, frailty, and impaired quality of life in an elderly patient with stage 3b CKD and to wonder if therapeutic interventions to avoid these potential CKD complications (10 -12) (8). The CKD-EPI equation (6) was developed to improve accuracy of GFR determination in patients with higher Modification of Diet in Renal Disease (MDRD) eGFR.…”