Estimated Glomerular Filtration Rate in Chronic Kidney Disease: A Critical Review of Estimate-Based Predictions of Individual Outcomes in Kidney Disease.

Chronic kidney disease (CKD) is generally regarded as a final common pathway of several renal diseases, often leading to end-stage kidney disease (ESKD) and a need for renal replacement therapy. Estimated GFR (eGFR) has been used to predict this outcome recognizing its robust association with renal disease progression and the eventual need for dialysis in large, mainly cross-sectional epidemiological studies. However, GFR is implicitly limited as follows: (1) GFR reflects only one of the many physiological functions of the kidney; (2) it is dependent on several non-renal factors; (3) it has intrinsic variability that is a function of dietary intake, fluid and cardiovascular status, and blood pressure especially with impaired autoregulation or medication use; (4) it has been shown to change with age with a unique non-linear pattern; and (5) eGFR may not correlate with GFR in certain conditions and disease states. Yet, many clinicians, especially our non-nephrologist colleagues, tend to regard eGFR obtained from a simple laboratory test as both a valid reflection of renal function and a reliable diagnostic tool in establishing the diagnosis of CKD. What is the validity of these beliefs? This review will critically reassess the limitations of such single-focused attention, with a particular focus on inter-individual variability. What does science actually tell us about the usefulness of eGFR in diagnosing CKD?

Subjective global assessment of nutrition, dialysis quality, and the theory of the scientific method in Nephrology practice.

In an era of evidence-based medicine and dialysis performance measures, there is strong motivation to find specific, objective, quantifiable, and reproducible parameters to characterize the clinical condition of chronic kidney disease patients and to present population-wide statistics that may describe quality of care in dialysis centers. Yet, in the last three decades, several studies demonstrated that while parameters including Kt/V urea, serum phosphorus, parathyroid hormone, serum cholesterol fulfill all these criteria, efforts to optimize these lab parameters failed to improve survival on dialysis. However, subjective assessments of nutrition including subjective global assessment and malnutrition-inflammation score, while not ideally suited for statistical analysis and not optimal from the point of view of scientific methodology due to their general, semi-quantifiable, subjective nature have, nevertheless, proved themselves as some of the strongest predictors of clinical outcomes in the dialysis population. Where does this paradox leave us? We propose that a deeper understanding of relevance of these variables in the dialysis population may improve appreciation of the clinical situation of individual patients and may result in a paradigm shift from dialysis adequacy to quality dialysis.

Sexual dysfunction in women with ESRD requiring hemodialysis.

BACKGROUND AND OBJECTIVES: The few existing studies of sexual dysfunction in women on hemodialysis are limited by small sample size. This large, cross-sectional study evaluated the prevalence and correlates of female sexual dysfunction in advanced kidney disease. DESIGN, SETTING, PARTICIPANTS, METHODS: A total of 1472 women with ESRD undergoing hemodialysis were recruited to a multinational, cross-sectional study conducted within a collaborative dialysis network in Europe and South America. Sexual dysfunction was identified by the Female Sexual Function Index. Correlates of self-reported sexual dysfunction were identified by regression analyses. RESULTS: Of the 1472 women, 659 completed questionnaires (45%). More than half (362 of 659 [55%]) lived with a partner, and 232 of 659 (35%) reported being sexually active. Of these 659 respondents, 555 (84%) reported sexual dysfunction. Women with a partner (282 of 362 [78%]) were less likely to report sexual dysfunction than those without a partner (273 of 297 [92%]) (P<0.001). Sexual dysfunction was independently associated with age, depressive symptoms, less education, menopause, diabetes, and diuretic therapy. Nearly all women who were not wait-listed for a kidney transplant and were living without a partner (249 of 260 [96%]) reported sexual dysfunction. More than half (128 of 232 [55%]) of sexually active women reported sexual dysfunction, associated with age, depressive symptoms, menopause, low serum albumin, and diuretic therapy. CONCLUSIONS: This descriptive study suggests most women on hemodialysis experience sexual problems. Additional research on the relevance of sexual dysfunction to symptom burden and quality of life in these women is needed.

Prevalence and correlates of erectile dysfunction in men on chronic haemodialysis: a multinational cross-sectional study.

BACKGROUND: Factors associated with erectile dysfunction in men on haemodialysis are incompletely identified due to suboptimal existing studies. We determined the prevalence and correlates of erectile dysfunction and identified combinations of clinical characteristics associated with a higher risk of erectile dysfunction using recursive partitioning and amalgamation (REPCAM) analysis. METHODS: We conducted a multinational cross-sectional study in men on haemodialysis within a collaborative network. Erectile dysfunction and depressive symptoms were evaluated using the erectile function domain of the International Index of Erectile Function questionnaire and the Center for Epidemiological Studies-Depression Scale, respectively. RESULTS: Nine hundred and forty-six (59%) of 1611 eligible men provided complete data for erectile dysfunction. Eighty-three per cent reported erectile dysfunction and 47% reported severe erectile dysfunction. Four per cent of those with erectile dysfunction were receiving pharmacological treatment. Depressive symptoms were the strongest correlate of erectile dysfunction [adjusted odds ratio 2.41 (95% confidence interval (CI) 1.57-3.71)]. Erectile dysfunction was also associated with age (1.06, 1.05-1.08), being unemployed (1.80, 1.17-2.79) or receiving a pension (2.05, 1.14-3.69) and interdialytic weight gain (1.9-2.87 kg, 1.92 [CI 1.19-3.09]; >2.87 kg, 1.57 [CI 1.00-2.45]). Married men had a lower risk of erectile dysfunction (0.49, 0.31-0.76). The prevalence of erectile dysfunction was highest (94%) in unmarried and unemployed or retired men who have depressive symptoms. CONCLUSIONS: Most men on haemodialysis experience erectile dysfunction and are untreated. Given the prevalence of this condition and the relative lack of efficacy data for pharmacological agents, we suggest that large trials of pharmacological and non-pharmacological interventions for erectile dysfunction and depression are needed.

Genetic polymorphisms and the risk of progressive renal failure in elderly Hungarian patients.

The relationship between renal disease progression and genetic polymorphism of enzymes influencing endothelial function remains incompletely understood. We genotyped three cohorts of elderly Hungarian patients: 245 patients with end-stage renal disease (ESRD) on chronic hemodialysis (HD), 88 patients with mild chronic kidney disease (CKD), and 200 healthy controls. The underlying diagnoses of renal diseases were primary glomerulonephritis, interstitial nephritis, hypertension, diabetic nephropathy, and hereditary diseases. We examined genetic polymorphisms of eight candidate genes associated with endothelial function: endothelial constitutive nitric oxide synthase (ecNOS) T-786C, endothelin-1 G5727T, methylenetetrahydrofolate reductase (MTHFR) C677T, paraoxonase-1 Q192R and M55L, angiotensinogen M235T, angiotensin-converting enzyme (ACE) I/D and angiotensin II type 1 receptor A1166C gene. Six gene polymorphisms were detected by real-time polymerase chain reaction with melting-point analysis, and two via allele-specific amplification and gel electrophoresis. Control group patients were in Hardy-Weinberg equilibrium for all tested genotypes. In ESRD patients attributed to hypertension, the endothelin gene G5727T GG genotype occurred significantly less but GT genotype more frequently (P < 0.01 for both). In ESRD patients attributed to primary glomerulonephritis, more ACE DD and less ID genotypes were found (P < 0.02 for both) than in the controls. The underlying diagnosis may modify the association of genetic polymorphism and dialysis-dependent ESRD.

Correlation of treatment time and ultrafiltration rate with serum albumin and C-reactive protein levels in patients with end-stage kidney disease receiving chronic maintenance hemodialysis: a cross-sectional study.

BACKGROUND: The relationship between treatment time, ultrafiltration rate (UFR) and inflammation has received limited exploration so far. METHODS: This is a cross-sectional cohort study of 12 hemodialysis clinics. Statistical models explored the association of multiple patient- and dialysis-specific covariates with low albumin (5 mg/dl) and calculated the ORs and 95% CIs. RESULTS: 616 patients with a mean age of 60.9 +/- 14.4 years participated in our study. Mean treatment time was 237.3 +/- 23.8 min and mean UFR was 7.0 +/- 4.0 ml/kg/h. In stepwise logistic regression, treatment time >4 h reduced the risk of low albumin (OR 0.397, 95% CI 0.235-0.672, p < 0.001). Congestive heart failure (OR 1.634, 95% CI 1.154-2.312, p = 0.006) and acute infection (OR 1.799, 95% CI 1.059-3.056, p = 0.03) were significant correlates of the risk of high CRP. There was no association between UFR and either CRP or albumin. CONCLUSION: Treatment time had a significant cross-sectional association with serum albumin but not with CRP.

Treatment time, chronic inflammation, and hemodynamic stability: the overlooked parameters in hemodialysis quantification.

Decades after the introduction of chronic maintenance hemodialysis, the optimal means of quantifying dialysis dose remains controversial. Differences of opinion in the international dialysis community lead to substantial diversity in everyday clinical practice. Several studies suggest that the well-recognized international mortality differences in hemodialysis populations may result from these divergent approaches to dialysis care. One of the main areas of divergence is the different degree of reliance on dialysis clearance when prescribing dialysis. The "clearance approach" implies that treatment quality is primarily dependent on efficient removal of uremic toxins as estimated by dialytic urea clearance. Urea can be rapidly removed by high efficiency dialysis in a relatively short time. The main alternative to this strategy is the "time approach" based on the recognition that longer or more frequent dialysis provides benefits beyond increasing urea removal. Some of the putative benefits are more effective volume and blood pressure control, better maintenance of hemodynamic stability because of slower ultrafiltration and removal of uremic toxins that do not behave like urea. Recently, chronic inflammation has been proposed to be an important predictor of outcome in dialysis patients. Inflammatory markers are commonly elevated in chronic renal failure and levels of these seem to correlate with malnutrition, maintenance of residual renal function, and volume control. The relationships between dialysis clearance, treatment time, chronic inflammation, volume control, and hemodynamic stability are explored in this review. We propose that a better understanding of these complex relationships may provide opportunities for improving outcomes of maintenance hemodialysis patients.