Derivation of Meaningful Change Thresholds for EORTC QLQ-C30 and QLQ-LC13 in Patients with Small Cell Lung Cancer.

Objectives: Small-cell lung cancer (SCLC) is associated with poor survival and is accompanied by symptoms that impact patients' quality of life. Although quality of life can be assessed by the EORTC 30-item core questionnaire (QLQ-C30) and 13-item lung cancer (QLQ-LC13) module, interpretation of meaningful improvement or deterioration within and between individuals is challenging. The objective of this study was to derive thresholds for interpretation of changes over time for the key scales of Coughing, Chest Pain, Dyspnea, Physical Functioning and Global Health Status (GHS).

Methods: Anchor- and distribution-based analyses were employed to derive meaningful within-patient change (MWPC) and meaningful between-group difference (MBGD) thresholds using data from the phase II DeLLphi-301 trial in patients with previously treated SCLC. Methods included estimating mean change scores, mixed models for repeated measures, classification statistics, receiver operating characteristic curves, alongside calculating half standard deviation and standard error of measurement.

Results: MWPC recommendations were ±33.3 for single item scales QLQ-LC13 Chest Pain and Coughing, ±16.7 for both QLQ-LC13 Dyspnea and QLQ-C30 GHS, and ±20.0 for QLQ-C30 Physical Functioning. Estimated MBGD thresholds ranged from ±6 for GHS to ±22 for Coughing.

Conclusion: This study is the first to estimate MWPC and MBGD thresholds specifically in patients with relapsed SCLC. Estimated threshold ranges are considered robust given the comprehensive considerations and triangulation of various methods and can help clinicians, researchers, and healthcare decision makers to evaluate the clinical meaningfulness to patients of changes in key SCLC scales over time.