According to a systematic review published in May 2020 [8], the cumulative incidence of reoperation in two RCTs was 7/115 = 6.1% (95% CI 2.5–12.1%) in the drain group and 3/115 = 2.6% (95% CI 0.5–7.4%) in the no drain group. Cumulative incidence of additional drain was 1/86 = 1.2% (95% CI 0.03–6.3%) in the drainage group and 2/84 = 2.4% (95% CI 0.3–8.3%) in the no drain group. Assuming a 70% of overlap between the two procedures in the drain group, the estimated proportion of the composite outcome is 6.44%, while assuming a 35% overlap in the no drain group, the estimated proportion of the composite outcome is 4.16%.

Hence, we assumed a reference group proportion of 6.44%, and a treated group proportion of 10% under the null hypothesis of inferiority and 4.16% under the alternative hypothesis of non-inferiority. A sample size of 182 in each group, corresponding to 364 patients overall, achieves 80% power to detect a non-inferiority margin difference between the group proportions of 3.56% (= 10–6.44%), with a one-sided significance level of 5%. A power curve for treated group proportion ranging from 3 to 7% under the alternative hypothesis of non-inferiority is presented in Fig. 3.

Power curve as a function of treated group proportion ranging from 3 to 7% under the alternative hypothesis of non-inferiority. P0 (proportion in the control group) = 6.4%; alpha = 0.05; n1 = n2 = 182; P1.0 (proportion in the treated group under the null hypothesis of inferiority) = 10%. The test statistic used is the one-sided Z test (unpooled)

Considering a 10% dropout rate, 404 patients (202 in each group) are needed. In order to have a balanced percentage between total and subtotal gastrectomy, recruitment will end at 202 patients for each type of gastrectomy.

Note: The content above has been extracted from a research article, so it may not display correctly.



Q&A
Please log in to submit your questions online.
Your question will be posted on the Bio-101 website. We will send your questions to the authors of this protocol and Bio-protocol community members who are experienced with this method. you will be informed using the email address associated with your Bio-protocol account.



We use cookies on this site to enhance your user experience. By using our website, you are agreeing to allow the storage of cookies on your computer.