Development and calibration of a novel social relationship item bank to measure health-related quality of life (HRQoL) in Singapore

Abstract

Background Social relationships (SR) is an important domain of health-related quality of life. We developed and calibrated a novel item bank to measure SR in Singapore, a multi-ethnic city in Southeast Asia. Methods We developed an initial candidate pool of 51 items from focus groups, individual in-depth interviews and existing instruments that had been developed and/or validated for use in Singapore. We administered all items in English to a multi-stage sample of subjects, stratified for age and gender, with and without medical conditions, recruited from community and hospital settings. We calibrated their responses using Samejima’s Graded Response Model (SGRM). We evaluated a final 30-item bank with respect to Item Response Theory (IRT) model assumptions, model fit, differential item functioning (DIF), and concurrent and known-groups validity. Results Among 503 participants (47.7% male, 41.4% above 50 years old, 34.0% Chinese, 33.6% Malay and 32.4% Indian), bi-factor model analyses supported essential unidimensionality: explained common variance of the general factor was 0.805 and omega hierarchical was 0.98. Local independence was deemed acceptable: the average absolute residual correlations were < 0.06 and 1.8% of the total item-pair residuals were flagged for local dependence. The overall SGRM model fit was adequate ( p = 0.146). Five items exhibited DIF with respect to age, ethnicity and education, but were retained without modification of scores because they measured important aspects of SR. The SR scores correlated in the hypothesized direction with a self-reported measure of global health (Spearman’s rho = − 0.28, p < 0.001). Conclusion The 30-item SR item bank has shown acceptable psychometric properties. Future studies to evaluate the validity of SR scores when items are administered adaptively are needed. Electronic supplementary material The online version of this article (10.1186/s12955-019-1150-9) contains supplementary material, which is available to authorized users.

Developing item banks to measure three important domains of health-related quality of life (HRQOL) in Singapore

“…The next step towards using these domain-specific items banks in CATs is to calibrate them using IRT and evaluate the validity of test scores when these item banks are administered adaptively. To date, item-calibration of the domain specific item banks have been completed [15, 16]. Once fully developed, it is hoped that the resulting domain-specific instruments would make possible more precise measurements of HRQOL at the population and individual level, most especially in Singapore and Asia.…”

“…The developed item banks were subsequently calibrated using IRT (Stage 4); results of the item-calibration survey for the item bank on Social Relationships, and Positive Mindset have been published [15, 16]. Once validated, the calibrated, domain-specific item banks can be developed into CATs to measure HRQOL.…”

Development and calibration of a novel positive mindset item bank to measure health-related quality of life (HRQoL) in Singapore

“…The detailed methodology for the development of candidate items has been reported separately. [2, 10–12] In brief, we adapted the Patient Reported Outcome Measurement Information System (PROMIS) Qualitative Item Review (QIR) protocol[13], with input and endorsement from expert panels (comprised patients, members of the general public, and experts in psychology, social work and psychometrics). Items were generated from thematic analyses from focus groups and in-depth interviews and a literature search to identify studies that developed or validated a health-related quality of life instrument among adults in Singapore.…”