Satisfactory results of a psychometric analysis and calculation of minimal clinically important differences of the World Health Organization quality of life-BREF questionnaire in an observational cohort study with lung cancer and mesothelioma patients

Our plain-English summary of Satisfactory results of a psychometric analysis and calculation of minimal clinically important differences of the World Health Organization quality of life-BREF questionnaire in an observational cohort study with lung cancer and mesothelioma patients, by M. de Mol, S. Visser, J.G.J.V. Aerts, et al (BMC Cancer, 2018).

The study

• Authors: M. de Mol, S. Visser, J.G.J.V. Aerts, P. Lodder, J. de Vries, B.L. den Oudsten
• Journal: BMC Cancer
• Published: 2018;18(1):1173
• Cited by: 24 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: To determine the psychometric properties and minimal clinically important differences (MCIDs) of the World Health Organization Quality of Life-BREF (WHOQOL-BREF) in advanced stage lung cancer patients.

Methods: Patients (n = 153) completed the WHOQOL-BREF and the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30). Confirmatory factor analysis (CFA) was performed and reliability and construct validity determined. MCIDs were estimated with two distribution-based methods (0.5 standard deviation (SD) and 1 standard error of measurement (1 SEM)).

Results: CFA confirmed WHOQOL-BREF domain structure. All domains demonstrated good internal consistency (α > 0.70), except Social Relationships (α = 0.57). Nineteen of the 24 WHOQOL-BREF items had correlations of ≥ 0.40 with their intended domain. Four items had higher correlations with a domain other than their intended domain. Moderate to strong correlations were observed for corresponding domains of the two questionnaires, except for the social domains (r = 0.07). For 0.5 SD, MCIDs ranged from 0.88 to 1.55, and for 1 SEM MCIDs ranged from 1.76 to 2.72.

Conclusions: The WHOQOL-BREF has satisfactory psychometric properties in patients with advanced stage lung cancer, whereas the observed MCIDs provide a method for interpretation of scores.

In plain English

This Dutch study tested how well a general quality-of-life questionnaire, the WHOQOL-BREF, worked in patients with advanced lung cancer. It did not study asbestos exposure. Patients came from PERSONAL, a prospective cohort at four Dutch hospitals of people with non-squamous non-small cell lung cancer or unresectable malignant pleural mesothelioma who were starting pemetrexed chemotherapy. Of 191 enrolled, 153 completed the questionnaires sufficiently. Seven of these had mesothelioma, and no separate results were given for them. Before their first chemotherapy cycle, patients answered the WHOQOL-BREF and a cancer-specific questionnaire, the EORTC QLQ-C30. Three of the four domains had acceptable internal consistency (Cronbach's alpha 0.77 to 0.81), while Social Relationships had 0.57. Correlations with the cancer questionnaire were generally low, except for Physical Health. Estimated minimal clinically important differences were 0.88 to 1.55 points by one method and 1.76 to 2.72 by another. The authors concluded the questionnaire had satisfactory reliability and validity in advanced lung cancer. They noted a small sample and a lack of test-retest data.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Psychometric (questionnaire validation) analysis of baseline data from a prospective observational multi-center cohort study (PERSONAL)
• Who was studied: 153 of 191 enrolled patients in the Netherlands (four hospitals, recruited October 2012 to November 2014) with non-squamous non-small cell lung cancer or unresectable malignant pleural mesothelioma starting pemetrexed. 7 of the 153 (4.6%) had mesothelioma.
• Exposure: No asbestos exposure was studied. Patients completed the WHOQOL-BREF and EORTC QLQ-C30 quality-of-life questionnaires after diagnosis and before starting pemetrexed chemotherapy (alone or with a platinum compound).
• Main results:
  • Confirmatory factor analysis of the four-domain structure: after two modifications, the CFI rose from 0.854 to 0.896 and the RMSEA fell from 0.069 to 0.058. Both approached the criteria for satisfactory to good fit.
  • Internal consistency (Cronbach's alpha) was 0.81 (95% CI 0.76 to 0.85) for Physical Health, 0.77 (95% CI 0.71 to 0.83) for Psychological Health, and 0.77 (95% CI 0.70 to 0.82) for Environment.
  • Social Relationships had a Cronbach's alpha of 0.57 (95% CI 0.43 to 0.68), below the 0.70 acceptability threshold.
  • Five items (Sleep, Body Image, Sex, Physical Environment, Finance) did not reach a correlation of 0.40 with their intended domain. Four items (Sleep, Body Image, Self-esteem, Personal Relationships) correlated more strongly with another domain than with their own.
  • Correlations between WHOQOL-BREF domains and EORTC QLQ-C30 scales were generally low. Only Physical Health showed moderate to high correlations (except with Cognitive Functioning). Social Relationships showed the lowest correlations.
  • Mean General Facet, Physical Health and Psychological Health scores differed significantly across ECOG performance grades 0, 1, and 2 or higher.
  • Minimal clinically important differences estimated by the 0.5 standard deviation method ranged from 0.88 to 1.55 points.
  • Minimal clinically important differences estimated by the 1 standard error of measurement method ranged from 1.76 to 2.72 points.
• The authors' conclusion: The authors concluded that the WHOQOL-BREF has satisfactory reliability and validity in patients with advanced lung cancer. They proposed the estimated minimal clinically important differences to help interpret scores in studies and in clinical practice.
• Limitations the authors state:
  • No test-retest reliability analysis could be performed, so the 1 SEM estimates used the lower bound of the confidence interval of Cronbach's alpha.
  • The study used confirmatory factor analysis and multi-trait/multi-method methods rather than the increasingly used Rasch analysis.
  • The sample was smaller than the recommended 200 patients, and some observed differences may reflect chance.
  • Confidence intervals for the model fit indices could not be calculated, so fit could not be formally compared with the original field trial.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Quality of Life, Cohort Study, Lung Cancer, Mesothelioma.

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