Application of Rasch Analysis for Development and Psychometric Properties of Adolescents' Quality of Life Instruments: A Systematic Review

Background: Due to the importance of assessing quality of life (QoL) in healthy and ill adolescents, the evaluation of psychometric properties of these questionnaires is important. Objective: To investigate the application of Rasch analysis in psychometric assessment studies on adolescents' QoL instruments, and to evaluate the quality of reporting Rasch parameters in these studies. Methods: This systematic review was conducted by searching for papers in electronic databases PubMed, Web of Science, EMBASE, Cochrane Library and Scopus until December 2018. Results: After screening 122 papers, 31 remained in the study. Around 68% of the studies used the Rasch analysis for instrument testing and 32% for the development of new instruments. In 77.4% of studies, both classical and Rasch methods were used parallel to data analysis. In 32.2% of studies, healthy adolescents were the main target group. The most commonly used instrument in Rasch studies was, KIDSCREEN, administered in different countries. Six Rasch parameters were reported with a higher percentage in the studies. Major reported parameters of Rasch analysis were application of the software program (96.7%), test of item fit to the Rasch model (93.5%), unidimensionality (80.6%), type of the identified mathematical Rasch model (74.1%), threshold (58%) and differential item functioning (54.8%). Based on the psychometric evaluation of the QoL instruments, 71% of studies showed acceptable results. Conclusion: The application of the Rasch model for psychometric assessment of adolescents' QoL questionnaires has increased in recent decades. But, there is still no strong and commonly used critical appraisal tool or guideline for the evaluation of these papers.