Comment to Oral BCAA Trials
Three papers presented during the meeting concerned double blind placebo controlled trials evaluating the effect of oral branched chain amino acids (BCAA) on portal-ystemic encephalopathy (PSE). Two of these carefully designed trials1,2 arrived at the conclusion that BCAA do have a favorable influence on low grade and latent PSE. Contrary to this, Eriksson et al.3 in an equally elaborate trial did not find any significant differences. To reconcile these divergent statements a few comments are necessary: the first comment is a numerical one. Both Egberts and Horst included more than 20 patients in their respective studies, whereas the study of Eriksson et al. concerned only 7 patients. Conclusions derived from small size studies such as this can be valuable if the study is carefully designed and if statistically significant differences are found. However, if statistically significant differences are not found, the conclusions to be drawn from the results are extremely limited. Certainly, the general conclusion that there is no difference can not be drawn. This is due to the fact that the probability of a type II error — i.e. the non-detection of a true difference — increases for decreasing number of patients included in the study. Thus, any conclusion derived from statistical significant differences in a study including 22 patients can not be contradicted on the basis of negative results in 7 patients. As pointed out by Freiman et al.4 most clinical trials arriving at negative results are too small, and due to the high probability of a type II error are far from justifying the conclusion that there is no difference.
KeywordsHepatic Encephalopathy Branch Chain Amino Acid Double Blind Placebo Control Trial Placebo Period Favorable Influence
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- 1.D, Horst, N. Grace, H. O. Conn, E. Schiff, S. Schenker, A. Viteri, D. Law, and C. E. Atterbury, A double-blind randomized comparison of dietary protein and an oral branched chain amino acid (BCAA) solution in cirrhotic patients with chronic portal-systemic encephalopathy (PSE), AISF Symposium on Hepatic Encephalopathy, Rome, Nov. (1982).Google Scholar
- 2.E. H. Egberts, W. Hamster, H. Schomerus, and P. Jürgens, Effective treatment of latent porto-systemic encephalopathy (PSE) with oral branched chain amino acids (BCAA), AISF Symposium on Hepatic Encephalopathy, Rome, Nov. (1982).Google Scholar
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