Objective: The objective of this study was to assess the test-retest reliability of an interactive voice response (IVR) version
of the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30.
Methods: A convenience sample
of outpatient cancer clinic patients (n = 127) was asked to complete the IVR version of the QLQ-C30 twice, 2 days apart. The
QLQ-C30 is a 30-item, cancer-specific questionnaire composed of single-item and multi-item scales. The instrument has five
functional scales (physical, role, cognitive, emotional, and social), three symptom scales (fatigue, pain, and nausea/vomiting),
and a global quality-of-life scale. The remaining single items assess dyspnea, appetite loss, insomnia, constipation, diarrhea,
and financial problems. The analyses focused on intraclass correlation coefficients (ICCs), comparing the ICC 95 % lower confidence
interval (CI) value with a critical value of 0.70.
Results: The ICCs for the nine multi-item scales were all above
0.69, ranging from 0.698 to 0.926 (ICC 95 % lower CI value range 0.588-0.895). All of the scales were significantly different
from our threshold reliability of 0.70, with the exception of the cognitive functioning scale. The ICCs for the six single
items ranged from 0.741 to 0.883 (ICC 95 % lower CI value range 0.646-0.835), and three of the six were statistically different
from 0.70. The evidence supports the stability of 11 of the 15 scores obtained on the IVR version of the QLQ-C30 upon repeated
Conclusion: The measurement equivalence of the IVR and paper versions of the QLQ-C30 has been reported
elsewhere. This analysis provides evidence demonstrating adequate test-retest reliability of the IVR version for 11 of the
QLQ-C30’s 15 scores.