Studie zur Vorbeugung von
Darmpolypen mit Grüntee-Extrakt

Statistical analysis

The trial results will be analyzed by intention-to-treat and the per-protocol analysis. In analogy to [15] a modified intention-to-treat approach will be performed including all randomized subjects with a follow-up colonoscopy, irrespective of adherence to the study medication. Lacking values will be estimated using the Multiple Imputation MCMC method [34].

The per-protocol analysis will be done in all subjects who completed the whole course of the study. Safety will be assessed in all patients who took at least one capsule of the study medication.

Statistical analysis of the primary outcome

The study's aim is to check the following hypothesis: the regular intake of green tea extract (at least 300 mg daily) over three years results in a decrease of the incidences of colorectal adenomas. This primary outcome based on the intention-to-treat-population will be tested confirmatively by the one-sided χ2-Test [35] with a significance level of 5%.

The impact of other variables (e. g. study center, intake of low-dose ASS) related to the recurrence of adenomas will be explorative controlled by the logistic regression model [36]. Concerning the time of the recurrence of adenomas, the impact of other variables will be explorative controlled with the Cox proportional hazard model [37].

With the help of this multivariate analysis both the relative risks and the 95% confidence-intervals can be calculated.

Statistical analyses of the secondary outcome

How much other impact factors affect the risk of the incidence of metachronous adenomas will be analyzed explorative.

In addition, genetic and biochemical biomarkers for the recurrence of adenomas or the development of dysplasia and carcinoma will be analyzed explorative in the blood samples entered into the biobanking subproject.

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