Beta-2 microglobulin clearance in high-flux dialysis and convective dialysis modalities: a meta-analysis of published studies.

Background: Recent meta-analyses suggest that higher removal of beta-2 microglobulin (ß2M) with either high-flux (HFD) dialysis or hemodiafiltration (HDF) may be associated with decreased total and cardiovascular mortality in dialysis patients. However, there are limited data about the performance of high flux dialyzers and/or convective therapies in removing ß2M. Methods: This is a random effects meta-analysis and meta-regression of data extracted from randomized controlled trials and observational studies in hemodialysis, hemofiltration and HDF regarding the efficiency of high flux dialyzers to remove ß2M. Studies were searched using ProQuest in SCOPUS, EMBASE and MEDLINE. Results: We included 69 studies from 1 January 2001 to 12 June 2017 on 1879 patients with 6771 available measurements. Average ß2M clearance was 48.75 mL/min [95% confidence interval (CI) 42.50-55.21] for conventional HF dialysis, and 87.06 mL/min (95% CI 75.08-99.03) for convective therapies (hemofiltration and HDF) with substantial heterogeneity among studies [P (Q) ≤ 0.001]. In multivariable meta-regression analyses, we found significantly higher ß2M clearance for polyarylethersulfone dialyzers when used for HFD and polysulfone membranes in convective therapies. However, the mass of ß2M removed into the dialysate did not depend on membrane material. Adjusted dialysate-side (-22.279, 95% CI -9.8 to -34.757, P < 0.001) ß2M clearances were significantly lower than whole blood clearances, suggesting that adsorption contributes substantially to ß2M removal. Higher Kuf, blood flow and substitution fluid rates but not dialysate flow rates were associated with statistically significant and clinically meaningful elevation in ß2M clearance from the body independent of the dialysis modality. Conclusions: Membrane composition and characteristics, modality (convective versus diffusive), blood flow rates and substitution fluid rates in HDF play a significant role in the efficient removal of ß2M from the body in both diffusive and convective dialysis.

Clinical Inquiry: Do ACE inhibitors or ARBs help prevent kidney disease in patients with diabetes and normal BP?

Yes for angiotensin-converting enzyme (ACE) inhibitors, no for angiotensin receptor blockers (ARBs). A 2011 meta-analysis of 5 RCTs (total 2975 patients) that compared ACE inhibitor therapy with placebo in diabetic patients without hypertension and albuminuria found that ACE inhibitors reduced the risk of new-onset microalbuminuria or macroalbuminuria by 18% (relative risk [RR]=0.82; 95% confidence interval [CI], 0.73-0.92).

Risk factors for acute kidney injury in older adults with critical illness: a retrospective cohort study.

BACKGROUND: Risk for acute kidney injury (AKI) in older adults has not been evaluated systematically. We sought to delineate the determinants of risk for AKI in older compared with younger adults. STUDY DESIGN: Retrospective analysis of patients hospitalized in July 2000 to September 2008. SETTING & PARTICIPANTS: We identified all adult patients admitted to an intensive care unit (n=45,655) in a large tertiary-care university hospital system. We excluded patients receiving dialysis or a kidney transplant prior to hospital admission and patients with baseline creatinine levels ≥ 4mg/dL, liver transplantation, indeterminate AKI status, or unknown age, leaving 39,938 patients. PREDICTOR: We collected data for multiple susceptibilities and exposures, including age, sex, race, body mass, comorbid conditions, severity of illness, baseline kidney function, sepsis, and shock. OUTCOMES: We defined AKI according to KDIGO (Kidney Disease: Improving Global Outcomes) criteria. We examined susceptibilities and exposures across age strata for impact on the development of AKI. MEASUREMENTS: We calculated area under the receiver operating characteristic curve (AUC) for prediction of AKI across age groups. RESULTS: 25,230 (63.2%) patients were 55 years or older. Overall, 25,120 (62.9%) patients developed AKI (69.2% aged ≥55 years). Examples of risk factors for AKI in the oldest age category (≥75 years) were drugs (vancomycin, aminoglycosides, and nonsteroidal anti-inflammatories), history of hypertension (OR, 1.13; 95% CI, 1.02-1.25), and sepsis (OR, 2.12; 95% CI, 1.68-2.67). Fewer variables remained predictive of AKI as age increased and the model for older patients was less predictive (P<0.001). For the age categories 18 to 54, 55 to 64, 65 to 74, and 75 years or older, AUCs were 0.744 (95% CI, 0.735-0.752), 0.714 (95% CI, 0.702-0.726), 0.706 (95% CI, 0.693-0.718), and 0.673 (95% CI, 0.661-0.685), respectively. LIMITATIONS: Analysis may not apply to non-intensive care unit patients. CONCLUSIONS: The likelihood of developing AKI increases with age; however, the same variables are less predictive for AKI as age increases. Efforts to quantify risk for AKI may be more difficult in older adults.