Open AccessDevelopment and calibration of a novel positive mindset item bank to measure health-related quality of life (HRQoL) in Singapore
Author(s) -
Yu Heng Kwan,
Elenore Judy B. Uy,
Dianne Bautista,
Xiaohui Xin,
Yunshan Xiao,
Geok Ling Lee,
Mythily Subramaniam,
Janhavi Ajit Vaingankar,
Mei Fen Chan,
Nisha Kumar,
Yin Bun Cheung,
Terrance Chua,
Julian Thumboo
Publication year - 2019
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0220293
Subject(s) - malay , item response theory , item bank , local independence , differential item functioning , mindset , ethnic group , quality of life (healthcare) , demography , psychology , statistics , construct validity , gerontology , medicine , clinical psychology , psychometrics , mathematics , computer science , philosophy , linguistics , artificial intelligence , sociology , anthropology , psychotherapist
Background Positive mindset (PM) is an important domain of health-related quality of life in Singapore, a multi-ethnic urban city state in Southeast Asia. We therefore developed and calibrated a novel item bank to measure and improve PM. Methods We developed an initial candidate pool of 48 items from focus groups, in-depth interviews and existing instruments locally developed and validated for use in Singapore. We administered all items in English to a multi-stage sample stratified for age and gender, of subjects with and without medical conditions recruited from the community and a hospital, and calibrated their responses using Samejima’s Graded Response Model. We evaluated a final 36-item bank with respect to Item Response Theory (IRT) model assumptions, model fit, differential item functioning (DIF), concurrent and known-groups validity. Results Among 493 participants (49.3% male, 41.6% above 50 years old, 33% Chinese, Malay and Indian), bifactor model analyses supported unidimensionality: explained common variance of the general factor was 0.86 and omega hierarchical was 0.97. Local independence was deemed acceptable: the average absolute residual correlations were <0.06 and 3.3% of the total item-pair residuals were flagged for local dependence. The overall model fit was adequate and provided good coverage of the PM construct (theta range: -3.6 to +2.4). Five items exhibited DIF with respect to ethnicity and gender, but were retained without modification of scores because they measured important aspects of PM. Scores correlated in the hypothesized direction with a self-reported measure of global health (Spearman’s rho = -0.28, p<0.001) and discriminated between groups of participants with and without a self-reported diagnosis of a mood disorder (p = 0.007) adjusting for age, gender, ethnicity, education and marital status. Conclusion The 36-item PM item bank demonstrated satisfactory psychometric properties for the English-speaking Singaporean population. IRT model assumptions were sufficiently met and scores showed concurrent and known-groups validity. Future studies to evaluate the validity of PM scores when items are administered adaptively are needed.