Introduction: The EORTC Quality of Life (QL) Group has developed a questionnaire -the EORTC QLQ-CR29- for evaluating QL in colorectal cancer. The aim of this study is to assess the psychometric properties of the EORTC QLQCR29 when applied to a sample of Spanish patients.
Materials and methods: Eighty-four locally advanced rectal cancer patients in the treatment follow-up period after receiving surgery and neoadjuvant chemoradiotherapy were included in the study. Seventy subjects also had adjuvant chemotherapy. Patients completed both the EORTC QLQC30 and the QLQ-CR29 once. The psychometric evaluation of the questionnaire's structure, reliability, and convergent, divergent and known-groups validity was performed.
Results: Multitrait scaling analysis showed that three of the multi-item scales met the standards of convergent and discriminant validity. These same scales reached the 0.7 Cronbach's coefficient criterion or were close to it. In both analyses exceptions were observed in the blood and mucus in stool scale. Correlations between the scales of the QLQC30 and the module were low (r<0.02) in most cases. A few areas with more related content had higher correlations (r<0.05). Group comparison analyses showed differences in QL between groups of patients based on age, comorbidity, performance status, receipt of adjuvant chemotherapy and surgery modality.
Conclusions: The EORTC QLQ-CR29 is a reliable and valid instrument when applied to a sample of Spanish rectal cancer patients. These results are in line with those of the EORTC validation study.