RT Journal Article SR Electronic T1 Statistical analysis of the lactulose/breath hydrogen test in the measurement of orocaecal transit: its variability and predictive value in assessing drug action. JF Gut JO Gut FD BMJ Publishing Group Ltd and British Society of Gastroenterology SP 171 OP 175 DO 10.1136/gut.30.2.171 VO 30 IS 2 A1 D H Staniforth A1 D Rose YR 1989 UL http://gut.bmj.com/content/30/2/171.abstract AB The variability in the orocaecal transit time as measured by the lactulose/breath hydrogen method has been studied for three conditions: lactulose given with a meal, subjects sitting; lactulose given with a meal, subjects semirecumbent; lactulose given in aqueous solution, subjects semirecumbent. Thirty three healthy subjects attended on up to 12 occasions. It was found that administration of the lactulose with a meal significantly reduced the variability (p less than 0.05) and that adoption of the semirecumbent position further reduced variability. A power analysis was used to predict the number of subjects who would be required to show a given percentage change in orocaecal transit time at specified probabilities and powers. A graph and a table for use in the prediction of subject numbers at a probability of 5% and for powers of 50-99% is presented. A dose response curve for metoclopramide using the lactulose/breath hydrogen method is given for doses of 10, 15, and 20 mg.