Psychometric evaluation of the modified 19-item Bengali version of WHOQOL scale using Rasch analysis: a cross-sectional study of a rural district in Bangladesh

Abstract

Abstract Background This investigation aims to validate the psychometric properties of the modified 19-item Bengali version World Health Organization Quality of Life (WHOQOL) instrument in a typical healthy rural population in Bangladesh. Method The cross-sectional investigation collected 300 adults aged 18–85 years from Narail, a rural district of Bangladesh using a multi-stage cluster random sampling technique. Face-to-face interviews were conducted between July and August 2018 using an Android phone installed with a mobile data collection application CommCare. SPSS version 25; IBM. and a Rasch analysis software RUMM2030 were used for analyses. Results Results showed good overall fit, as indicated by a significant item-trait interaction with Bonferroni corrected p values, for physical ($$ {\upchi}_{(20)}^2 $$χ202 =32.13, p = 0.041), psychological ($$ {\upchi}_{(16)}^2 $$χ162 =14.93, p = 0.529), social ($$ {\upchi}_{(16)}^2 $$χ162 =12.62, p = 0.397), and environmental ($$ {\upchi}_{(20)}^2 $$χ202 =22.01, p = 0.339) domains. Item fit residual (IFR) values for all domains were within the desired limits, indicating no deviation from the expected relationship between the individual items and the rest of the items of the scale. Person fit residual (PFR) values also showed no person misfit among the samples, indicating item threshold are suitable for Rasch analysis. Reliability of the three domains of the 19-item WHOQOL scale was very good as indicated by a person separation index (PSI) = 0.873 and Cronbach’s Alpha (CA) = 0.881 for physical domain, PSI = 0.739 and CA = 0.746 for psychological domain, and PSI = 0.753 and CA = 0.781 for environmental domain. The social domain (PSI = 0.650 and CA = 0.669) had below acceptable reliability. All items in each domain had ordered thresholds except one item of the environmental domain. All four domains of the 19-item WHOQOL scale showed unidimensionality and was free from local dependency. Each domain also showed similar functioning for adults and older adults, males and females, no education and at least primary level of education, low and high socio-economic conditions. Conclusion The 19-item modified WHOQOL scale is confirmed as an efficient screening tool for measuring QoL among healthy rural Bangladeshi people. The scale could be implemented more widely. In particular, validations are required for diseases-specific population in Bangladesh to measure the Health Related Quality of life (HR-QoL) assessments for people suffering from chronic or other diseases.