Validation of the Sinhala version of the world health organization quality of life disability (WHOQOL-DIS) module for assessing quality of life in maxillofacial injury (MFI) patients in Sri Lanka

Abstract Background Physical disability is a significant health issue among maxillofacial injury (MFI) patients, leading to diminished quality of life (QOL). Cross-culturally adapted QOL instruments are essential in addressing their needs and optimizing resource allocation. This study aimed to translate and assess the validity and reliability of the World Health Organization Quality of Life – Disability (WHOQOL-DIS) module in Sinhala. Methods The WHOQOL-DIS consists of two parts; the World Health Organization Quality of Life – Brief version (WHOQOL-BREF) and the physical disability module (DISQOL). Since the WHOQOL-BREF Sinhala version was already available, DISQOL was adapted through the Modified Delphi process, overseen by healthcare field experts. Exploratory Factor Analysis (EFA) was used to evaluate the factorability of each item within its domain. To ensure construct validity, the convergent and discriminant validity of WHOQOL-BREF was assessed using the Multitrait-Multimethod Matrix Technique (MTMM). The analysis was conducted using SPSS statistical software version 22. A descriptive cross-sectional study was conducted from March to April 2023. Considering a non-probability consecutive sampling method, the study included 300 participants, comprising 250 MFI patients and 50 healthy individuals from the National Dental Teaching Hospital, Colombo, Sri Lanka. Results The Sinhala WHOQOL-DIS demonstrated validity across its seven domains, with high Cronbach’s alpha values indicating strong internal consistency for WHOQOL-BREF. DISQOL showed favourable reliability in key domains such as discrimination, autonomy, and inclusion. EFA supported the three primary DISQOL domains. Comparison with the SF-36 revealed strong correlations in relevant domains, confirming WHOQOL-BREF’s efficacy. Internal consistency and test-retest reliability exceeded 0.7 across most domains, except for social functioning. Conclusion The Sinhala WHOQOL-DIS is a valid and reliable instrument for evaluating the quality of life in individuals with physical disabilities due to MFI.