Reliability and validity of the Japanese version of the Work Limitations Questionnaire in employees of multiple private companies

Abstract

Objective: Previous studies reported that presenteeism costs the enterprises more than absenteeism. It becomes more important for corporate management to evaluate the outcomes of health promotion initiatives for their employees using work performance scales in Japan. We previously developed a Japanese version of Work Limitations Questionnaire (WLQ-J), a presenteeism scale developed by Lerner D. et al., and conducted an internet survey to examine the reliability and validity of WLQ-J with 710 employees from an IT company and a medical institution as subjects and reported the study results (Ida et al, 2012). The objective of the present study is to examine the reliability and validity of WLQ-J with employees from more companies and industries than those included in the previous study. Methods: We analyzed for 4,440 employees from 14 companies and 9 industries as subjects, who were selected from a total of 4,712 employees who answered both WLQ-J and Brief Job Stress Questionnaire (BJSQ) on the internet or paper survey conducted from September 2014 to January 2015. Results: The subjects' average age was 40.3±11.8 years (33.2±9.5 years in the previous study), with the percentage of males and females being 77.9% and 21.1%, respectively. The factor structure of WLQ-J accorded with that of the original version of WLQ. This supports the factorial validity of WLQ-J. In addition, sufficient internal consistency was recognized by Cronbach's alpha of the whole scale (0.87 for the present study and 0.97 for the previous study) and the subscales (0.77-0.94 for the present study and 0.88-0.95 for the previous study). The four subscale scores of WLQ-J were significantly correlated with the stress response of BJSQ with correlation coefficients of 0.28-0.64 for the present study and 0.39-0.60 for the previous study (p < 0.01 for both studies). Moreover, criterion-related validity of WLQ-J was also supported by the significant dose-response relationship between the subscale scores of WLQ-J and stress response of BJSQ (p < 0.01 for the previous study and p < 0.001 for the present study). Conclusions: The present study demonstrated the reliability and validity of WLQ-J in a population of employees from more companies and industries than those in the previous study, with its average age and percentage of males and females close to those of the whole Japanese industries. This suggests that WLQ-J is available as a stable scale for presenteeism in different populations in Japan.