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Randomized Controlled Trial
. 2013 Jan;24(1):231-7.
doi: 10.1093/annonc/mds220. Epub 2012 Aug 30.

Effect of completion-time windows in the analysis of health-related quality of life outcomes in cancer patients

D E Ediebah  1 , C Coens, J T Maringwa, C Quinten, E Zikos, J Ringash, M King, C Gotay, H-H Flechtner, J Schmucker von Koch, J Weis, E F Smit, C-H Köhne, A Bottomley; Gastro-Intestinal Tract Cancer Cooperative Group; Lung Cancer Cooperative Group; Quality of Life Department and Patient Reported Outcome and Behavioural Evidence (PROBE)
Affiliations
Randomized Controlled Trial

Effect of completion-time windows in the analysis of health-related quality of life outcomes in cancer patients

D E Ediebah et al. Ann Oncol. 2013 Jan.

Abstract

Background: We examined if cancer patients' health-related quality of life (HRQoL) scores on the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 are affected by the specific time point, before or during treatment, at which the questionnaire is completed, and whether this could bias the overall treatment comparison analyses.

Patients and methods: A 'completion-time window' variable was created on three closed EORTC randomised control trials in lung (non-small cell lung cancer, NSCLC) and colorectal cancer (CRC) to indicate when the QLQ-30 was completed relative to chemotherapy cycle dates, defined as 'before', 'on' and 'after'. HRQoL mean scores were calculated using a linear mixed model.

Results: Statistically significant differences (P<0.05) were observed on 6 and 5 scales for 'on' and 'after' comparisons in the NSCLC and two-group CRC trial, respectively. As for the three-group CRC trial, several statistical differences were observed in the 'before' to 'on' and the 'on' to 'after' comparisons. For all three trials, including the 'completion-time window' variable in the model resulted in a better fit, but no substantial changes in the treatment effects were noted.

Conclusions: We showed that considering the exact timing of completion within specified windows resulted in statistical and potentially clinically significant differences, but it did not alter the conclusions of treatment comparison in these studies.

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Figures

Figure 1
Figure 1
Raw mean profiles for the global health status/QoL scale for trial 1 by ‘before-or-on’ and ‘after’.
Figure 2
Figure 2
Raw mean profiles for the global health status/QoL scale for trial 2 by ‘before-or-on’ and ‘after’.
Figure 3
Figure 3
Raw mean profiles for the global health status/QoL scale for trial 3 by ‘before’, ‘on’ and ‘after’.
See this image and copyright information in PMC

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