Known-groups analysis
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COMPLICATIONS
The PIB score and the Decision Tree score were evaluated in patients who differed on variables hypothesized to influence the construct of interest. The magnitude of differences in scores characterized the degree to which the PIB score/Decision Tree score could distinguish among groups hypothesized a priori to be clinically distinct. Known-groups comparisons were assessed using data from the measurement period associated with Visit 2 in the psychometric analysis population. The known-groups were defined for the PGIS anchor by asking the following question: ‘Do you have any complications around your stoma today? If yes, overall, how would you describe the skin complications around your stoma today’. This led to three defined groups: ‘Group 1- no (reference)’, ‘Group 2- very mild or mild’, and ‘Group 3- moderate, severe, or very severe’.The magnitude of the differences was evaluated using between-group effect size estimates, calculated using the pooled standard deviation (SD) as the denominator, and based against the reference group as defined. The following cut-offs were used to interpret the magnitude of each effect size (ES): small change (ES = 0.20), moderate change (ES = 0.50), and large change (ES = 0.80) (