Psychometric Properties and Factorial Analysis of the Arabic McGill-QoL Questionnaire in Breast Cancer

Abstract

Purpose: This study aimed to assess the psychometric properties of the Arabic McGill Quality of Life Questionnaire-Revised (MQOL-R) in breast cancer survivors.

Patients and methods: One-hundred-forty breast cancer survivors were recruited and completed the questionnaire. The construct validity was assessed using confirmatory factor analysis (CFA). MQOL-R scores were correlated with Global Health Status/QoL and functional subscales of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30) for convergent validity. Reliability was estimated using Cronbach's alpha and intraclass correlation coefficients (ICC).

Results: CFA reproduced a four-factor model (ie, physical, psychological, existential, and social) with good fit indices (comparative fitting index = 0.980; root mean square error of approximation = 0.091), with all items significantly loading on their respective subscales. The total MQOL-R scores were correlated with the global health status/QoL and functional subscales of the EORTC QLQ-C30 (r = -0.172, P < 0.01). Known-group validity was proven by different MQOL-R scores according to functional status (50.62 ± 6.35 vs 45.98 ± 7.19, P < 0.01). Reliability was supported by good internal consistency and high test-retest correlation coefficients for the Arabic MQOL-R and its subscales (ICC range, 0.83-0.95).

Conclusion: The Arabic MQOL-R demonstrated adequate construct validity, factor structure, excellent test-retest reliability, and good internal consistency. This tool is valuable for assessing the quality of life in research and physical therapy rehabilitation settings among Arabic-speaking breast cancer survivors.

Keywords: breast cancer; quality of life; reliability; validity.

Figure 1

First-order (subscale) and second order (overall QOL) latent factors for MQOL-R. Factor loadings are standardized as revealed by the CFA. CFA: confirmatory factor analysis, rectangular: observed variables, Circles: factors, Numbers in circles below rectangular: item uniqueness values, Straight arrows towards observed variables from factors: loadings.