Con: Randomized controlled trials (RCT) have failed in the study of dialysis methods.

All progress in dialysis methods was made in research presented in case reports, case-control studies and other observational studies. On the contrary, randomized controlled trials (RCTs) did not bring any valuable results. Comparison of the value of peritoneal dialysis and hemodialysis (HD) in RCTs was not completed because of recruitment problems. Four RCTs in HD did not provide any useful data. The worst example was the National Cooperative Dialysis Study, which committed a Type II statistical error rejecting the time of dialysis as an important factor determining the quality of dialysis. This study also provided the basis for the establishment of the Kt/V index as a measure of dialysis adequacy. This index was accepted by the HD community, having been established in a sacrosanct RCT, led to short dialysis, and possibly higher mortality in the USA. The second trial (the HEMO study) committed a Type III statistical error asking the wrong question and did not bring any valuable results, but at least it did not lead to deterioration of dialysis outcomes in the USA. The third, the Frequent Hemodialysis Network Trial Group, did not bring forth any valuable results, but at least confirmed what was already known. The fourth, the Frequent Hemodialysis Network Nocturnal Trial, committed a Type II statistical error because of tremendous recruitment problems leading to an inadequate number of subjects. Moreover, the study methodology was absolutely unreliable.