Development of a disease specific questionnaire to supplement a generic tool for QoL in colorectal cancer.

Abstract

The need for disease-specific quality of life measures is highlighted in the literature. The psychometric properties of a supplementary disease-specific quality of life questionnaire developed for use with a generic Quality of Life tool in colorectal cancer patients are explored. Originally developed and tested in a German sample, the English translation was tested on a cohort of UK colorectal cancer patients. Relevance and acceptability was previously established in Germany. A rigorous factor analysis ascertained the underlying structure of two factors with a number of single items that were retained as clinically important symptom indicators. In considering validity, four conditions were assessed: Reliability using Cronbach's alpha; Construct validity by comparing patient subgroups; Clinical Validity, by testing the hypothesis that some patient subgroups experience worse quality of life; Construct Reliability using second order factor analysis with the EORTC QOLQ-C30 scales, confirming that the factors retained provide an excellent measure of physical discomfort and a good measure of physical well being. Two other such questionnaires were developed in parallel with this one and reported in the literature (FACT-C and QOLQ-CR38). However, this questionnaire provides a useful alternative tool for use in clinical trials of colorectal cancer treatments alongside a core QoL questionnaire especially when brevity is an important consideration.