Influence of dialysis membranes on outcomes in acute renal failure: A meta-analysis

Background. Considerable controversy exists as to whether synthetic (more biocompatible) dialysis membranes improve outcome in patients with acute renal failure (ARF) compared to cellulose-based membranes. Numerous trials conducted have yielded inconsistent results. Although the discordant results of existing studies could be explained by the varying degrees of biocompatibility among the different membranes used, these studies also had low statistical power. Thus, we sought to determine whether combining results from all published trials would provide a better estimate of the effect of membrane composition on survival in ARF. Methods. We performed a meta-analysis of all previously published prospective trials comparing the use of synthetic membranes with cellulose-based membranes for hemodialysis in patients with ARF. Results. Of the 10 prospective trials identified, eight trials (867 patients) provided survival data and six trials (641 patients) provided data on recovery of renal function. We used the Mantel-Haenszel test based on a fixed effects model to analyze the data. The cumulative odds ratio (OR) for survival in favor of synthetic membranes was 1.37 (95% CI: 1.02 to 1.83), P = 0.03 and that for renal recovery was 1.23 (95% CI: 0.90 to 1.68), P = 0.18. We performed a sensitivity analysis by stratifying studies on the basis of control group membrane type (unsubstituted or substituted cellulose) and found that the survival advantage for synthetic membranes was mainly limited to comparison with the unsubstituted cellulose group [OR 1.64 (95% CI: 1.10 to 2.45) vs. OR 1.20 (95% CI: 0.73 to 1.97)]. Conclusions. Synthetic membranes appear to confer a significant survival advantage over cellulose-based membranes. We could not demonstrate a similar benefit with use of synthetic membranes over cellulose-based membranes for recovery of renal function but sample size was limited. Finally, our results suggest that the survival disadvantage for cellulosebased membranes may be limited to unsubstituted cellulose (cuprophane) membranes.