CONTEXT: Clinical studies have over the past decade paid increasing attention to health-related quality of life data. Multiple questionnaires are often administered resulting in overlapping questions increasing patient burden.

OBJECTIVES: To examine the correlations between the commonly used European Organization for Research and Treatment of Cancer Quality of Life Questionnnaire-C30 (QLQ-C30) and the Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE™) on six coinciding items to determine consistency between overlapping items.

METHODS: Data were prospectively collected from patients attending two cancer centers in the U.K. Participants completed the QLQ-C30 version 3.0 every four weeks and the PRO-CTCAE at least once a week for 12 weeks. Data were collected via the Internet or an interactive voice response. For the six coinciding items in QLQ-C30 and PRO-CTCAE: pain, nausea, vomiting, constipation, diarrhea, and fatigue, comparisons were made between all possible related responses by aligning the four responses in the QLQ-C30 with two condensed versions of the five responses in the PRO-CTCAE. Consistency and reliability was determined with the intraclass correlation coefficient (ICC) and Cronbach's α.

RESULTS: About 247 patients completed 785 QLQ-C30 and 2501 PRO-CTCAE questionnaires. Moderate (ICC >0.5) to good (ICC >0.75) reliability and Cronbach's α >0.7 were found on all coinciding questions except for questions concerning the severity of nausea and vomiting as a result of relatively few patients responding to these questions. Items on frequency showed better correlations than the severity and interference items.

CONCLUSION: The good reliability and consistency between the QLQ-C30 and PRO-CTCAE support future attempts to minimize patient burden by shortening health-related quality of life questionnaires.