Validity, reliability and responsiveness of the EORTC QLQ-C30 and the EORTC QLQ-LC13 in Australians with early stage non-small cell lung cancer, CHERE Working Paper 2007/13

Aim: To assess the validity, reliability and responsiveness of two questionnaires, the QLQ-C30 and LC-13, as measures of health-related quality of life (HRQOL) in an Australian sample of people with early stage non-small cell lung cancer. Background: These two questionnaires are complementary components of the European Organisation for Research and Treatment of Cancer?s (EORTC?s) modular approach to measuring HRQOL: the QLQ-C30 is the core questionnaire, containing 30 items relevant to all cancers; the QLQ-LC13 contains 13 items specific to lung cancer. Methods: These two complementary questionnaires were assessed with data obtained from 183 participants of a randomised control trial investigating the use of Positron Emission Tomography in the management of stage I or II non-small cell lung cancer. A cohort of 173 participants, were treated by surgery and then followed for two years. Participants completed HRQOL questionnaires before the PET scan, before and after surgery, one month after surgery, and then four monthly for two years. Construct validity was tested with confirmatory factor analysis and correlation analysis was used to test for convergent/divergent validity. Discriminant validity was tested by assessing the sensitivity of the scales to the effects of moving from early to late stage disease, asymptomatic to mildly symptomatic, and to the effects of age, gender and number of comorbitities. Mean differences (standardized response means (SRM)) and effect sizes were estimated for: patients with Stage 1/11 and metastatic disease; ECOG score 0 and ECOG score 1; older and younger patients; men and women; patients with no comorbidities and those with 1 or more comorbidities. Reliability was assessed in terms of internal consistency and test-retest reliability. Responsiveness to the effects of major thoracic surgery, adjuvant radiotherapy, and disease recurrence was assessed by estimating mean differences (standardized response meansSRM?s and effect sizes for patients who underwent surgery, radiotherapy and whose disease recurred, respectively. Results: The factor structure reported previously was replicated in this sample, confirming the questionnaires? construct validity. Most scales demonstrated good to excellent internal consistency (Cronbach?s alpha range: 0.86 ? 0.94); the exceptions were the cognitive function (0.68) and nausea/vomiting scales (0.67). Test-retest reliability was generally good (intraclass correlation (ICC) range: 0.70 ? 0.81); the exceptions were the pain and nausea/vomiting scales (ICC 0.56 and 0.42). Most scales were sensitive to the large effect of moving from early to later stage disease with (SRM range: 21.3 ? 54.0; effect size range:1.14 ? 1.97 (except for emotional functioning: 13.7; 0.60)). The scales were also sensitive to small effects, detecting small to moderate differences for age (large for social functioning) and comorbidities, and small differences for moving from asymptomatic to mildly symptomatic disease, and for age. Responsiveness was also confirmed with most scales responsive to the large expected effects of surgery and disease progression ( SRM range: 21.6 ? 41.4; effect size range: 0.94 ? 1.89 (emotional functioning: 5.5; 0.19)). Conclusions: The QLQ-C30 and QLQ-LC13, when used together, provide a valid, reliable and responsive measure of HRQOL in Australians with early stage non-small cell lung cancer.