International phase IV validation study of an EORTC quality of life questionnaire for testicular cancer patients: the EORTC QLQ-TC26

• Main Authors: Monika Sztankay, Neil K. Aaronson, Juan I. Arraras, Umberto Basso, Uros Bumbasirevic, Fabio Efficace, Johannes M. Giesinger, Colin D. Johnson, Marieke van Leeuwen, Anne S. Oberguggenberger, Roman Sosnowski, Teresa Young, Bernhard Holzner, on behalf of the European Organisation for Research and Treatment of Cancer Quality of Life Group (EORTC QLG)
• Format: Article
• Language: English
• Published: BMC 2018-11-01
• Series: BMC Cancer
• Subjects: Testicular cancer; Health-related quality of life; EORTC; Psychometric validation; Patient-reported outcome
• Online Access: http://link.springer.com/article/10.1186/s12885-018-5036-8

Abstract Background Given the high cure-rate for testicular cancer (TC) and the patients’ young age, comprehensive evaluation of health-related quality of life (HRQOL) is an important consideration in this patient population. The EORTC QLQ-TC26 questionnaire module has been developed to supplement the EORTC QLQ-C30 in assessing TC-specific HRQOL in clinical trials and routine clinical practice. This international, multicentre phase IV validation study evaluated the psychometric properties of the new module. Methods This international, multicentre phase IV validation study enrolled testicular cancer patients from seven European countries. Patients completed the EORTC quality of life core questionnaire EORTC QLQ-C30 and the QLQ-TC26 at two consecutive time points and a debriefing questionnaire regarding the QLQ-TC26 after baseline assessment. Psychometric evaluation included examination of the hypothesized module scale structure, internal consistency and test-retest reliability, known-groups validity, responsiveness to change over time and cross-cultural acceptability. Results Data from 313 patients (mean age 38.6, SD 9.5) were analysed. All items exhibited a high completion rate with less than 2.4% missing values except for the sexuality items (up to 8.8%). The confirmatory factor analysis supported the hypothesised scale structure of the QLQ-TC26. Test-retest reliability was good for 8 of 12 scales (intraclass correlation: R t1|t2 ranged from 0.71–0.91) and four scales did not meet the acceptable criteria. Internal consistency was good for all twelve scales (Cronbach alpha = 0.79–0.90), except Communication (alpha = 0.67) and Sexual Functioning (alpha = 0.62). The module was able to distinguish clearly between patients with differing clinical status. Responsiveness to change over time was acceptable. Conclusion The EORTC QLQ-TC26 is a valid, reliable and well-accepted condition-specific questionnaire, supplementing the EORTC QLQ-C30, for the assessment of testicular cancer patients’ HRQOL in clinical trials.