Floor and ceiling effects in the EORTC QLQ‐C30 Physical Functioning subscale among patients with advanced or metastatic breast cancer

Abstract

BACKGROUND:The European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire Core 30 Physical Functioning subscale is a widely used patient-reported outcome measure that quantifies cancer patients' physical functioning. Strong floor/ceiling effects can affect a scale's sensitivity to change. The aim of this study was to characterize floor/ceiling effects of the physical functioning domain in patients with advanced/metastatic breast cancer enrolled in commercial clinical trials and a community-based trial. METHODS: The clinical trial cohort comprised patients from 5 registrational trials submitted to the Food and Drug Administration for review (2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017). The community cohort comprised a subgroup of patients from the Alliance Patient Reported Outcomes to Enhance Cancer Treatment (PRO-TECT) trial. The distribution of patient responses to Physical Functioning items and the summed score were assessed at the baseline and 3-month follow-up for both cohorts. Descriptive statistics were used to determine floor/ceiling effects at the item and scale levels. RESULTS: The clinical trial cohort and the community cohort consisted of 2407 and 178 patients, respectively. Twenty-four percent or more of the respondents reported "not at all" for having trouble/needing help with each Physical Functioning item across both cohorts and measurement time points. Fourteen to twenty percent of the patients scored perfectly (100 of 100) on the Physical Functioning subscale summary measure (where higher scores indicated better physical functioning) across both cohorts and time points. CONCLUSIONS: Minor floor effects and notable ceiling effects were found at the item and scale levels of the Physical Functioning subscale, regardless of cohort, and this creates some uncertainty about its ability to detect changes in physical functioning among high-functioning patients. Investigators may consider adding additional high-functioning items from the EORTC's item library to more accurately describe the impact of anticancer treatment on patients' physical functioning.

Reply to “Another look at floor and ceiling effects in the EORTC QLQ‐C30 Physical Functioning subscale and possible solutions”

“…As stated in our article, 1 the EORTC QLQ-C30 PF domain serves as an important measure for PF and has significant practical advantages for use in commercial clinical trials, including its wide-ranging cultural and linguistic validation. Descriptive data on PF using the QLQ-C30 PF and other available PF short forms can provide important complementary information on how patients function while exposed to investigational treatments.…”

“…We thank Vachon and colleagues for their comments on our publication regarding floor and ceiling effects in the European Organisation of Research and Treatment for Cancer (EORTC) Quality of Life Questionnaire Core 30 (QLQ‐C30) Physical Functioning (PF) domain 1 . In this article, we assessed the QLQ‐C30 PF domain for floor and ceiling effects at both the item and scale levels in patients with advanced/ metastatic breast cancer.…”

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We thank Vachon and colleagues for their comments on our publication regarding floor and ceiling effects in the European Organisation of Research and Treatment for Cancer (EORTC) Quality of Life Questionnaire Core 30 (QLQ-C30) Physical Functioning (PF) domain. 1 In this article, we assessed the QLQ-C30 PF domain for floor and ceiling effects at both the item and scale levels in patients with advanced/ metastatic breast cancer. On the basis of our results, we suggested that the PF domain might have limited sensitivity for detecting changes in PF among patients with advanced/ metastatic breast cancer who are high functioning at the baseline.Vachon et al point out that the definition we used for a ceiling effect at the scale level (≥93.3 of 100) is not conventional.

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Another look at floor and ceiling effects in the EORTC QLQ‐C30 Physical Functioning subscale and possible solutions

“…Recently, Cancer published an article entitled “Floor and ceiling effects in the EORTC QLQ‐C30 Physical functioning subscale among patients with advanced or metastatic breast cancer,” 1 in which the authors aimed to evaluate the responsiveness of the Physical Functioning (PF) subscale of the European Organisation of Research and Treatment for Cancer (EORTC) Quality of Life Questionnaire Core 30 (QLQ‐C30) 2 among patients with advanced/metastatic breast cancer. The authors concluded that the “Physical Functioning domain of the EORTC QLQ‐C30 was associated with … notable ceiling effects,” and they suggested that the QLQ‐C30 PF subscale might not be able to detect changes among high‐functioning patients.…”

“…In their introduction, the authors defined ceiling effects as “when >20% of the respondents select the best response option.” 1 To be in line with this conventional operationalization of ceiling effects, 3 the authors then should have used the maximum score of the PF scale (100) in their analysis. However, in contrast to another recent publication examining floor/ceiling effects among patients with metastatic breast cancer, 4 the authors then used a different definition in their Materials and Methods section (ie, ≥ 93.3 of 100), and the reasons underlying this decision remain unclear.…”