Page 160 - Risk quantification and modification in older patients with colorectal cancer
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Chapter 8
For both the QLQ-C30 and the QLQ-C38, answer categories range from one (‘not at all’) to four (‘very much’) expect for global health which ranges from 0 (‘very poor) to 7 (‘excellent’). All scales are linearly transformed according to the guidelines of the EORTC to reach a scale range of 0 to 100. A higher score on the functional scales, the global health item and summary score implies better HRQoL, whereas higher scores on symptom scales represent higher symptom burden.
We compared patients on four QLQ-C30 functioning scales (physical functioning, role functioning, emotional functioning, cognitive functioning), two QLQ-C30 symptom scales (fatigue and pain), the global health scale, the summary score and four QLQ-CR38 scales (body image, future perspective, gastrointestinal problems and weight loss). These more general outcomes were chosen based on clinical grounds. This also reduced the risk of type I errors introduced by multiple testing.
Functional assessment
For functional assessment, we used the ADL Barthel Index. It consists of 10 questions with 2 to 4 answer options, with each option scoring 0 to 3 points, and a maximum overall score of 20.29,30 For this study we stratified patients based on this index and considered patients fully functionally ‘independent’ with a Barthel Index of 19 or higher following the definition of the Stroke Unit Trialists’ Collaboration.31 Patients with a score lower than 19 were considered functionally ‘dependent’.
Statistical analyses
Following the EORTC guidelines, in case of missing items within a scale, the scale score was calculated by using only those items for which values were available provided that at least half of the items in the scale were completed. Likewise, at least 50% of the questions of the Barthel Index were needed to calculate a score.
Sociodemographic and clinical characteristics are presented with mean and standard deviation (SD) for normally distributed continuous variables and median with interquartile range (IQR) for non-normally distributed variables. Sociodemographic and clinical characteristics were compared using the two sided X2 or t-test.
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