Effects of a gratitude intervention program on work engagement among Japanese workers: a protocol for a cluster randomized controlled trial

Background: Work engagement is one of the most important outcomes for both employees and employers. Although the findings to date, integrated 40 intervention studies aiming to improve work engagement, consistent results have not yet been produced, suggesting the importance of further intervention studies. This study aims to investigate the effects of gratitude intervention programs focused on two important work engagement factors among Japanese workers: personal and job resources. Methods: This study will be a two-arm, parallel-group cluster (organization) randomized control trial. Japanese organizations and nested employees will be recruited through the first author's acquaintances using snowball sampling. Organizations that meet the inclusion criteria will be randomly allocated to intervention or control groups in a 1:1 ratio within the company unit. The intervention groups will be provided with a 1-month long gratitude intervention program, which aims to promote reciprocal gratitude exchanges within the same organization. The program consists of psychoeducation, gratitude lists, and behavioral gratitude expression. The control groups will not receive any intervention. The primary outcome will be work engagement measured by the Japanese version of the Utrecht Work Engagement Scale at baseline and after 1 (immediate post-survey), 3, and 6 months. Multilevel latent growth modeling will be conducted to examine the effectiveness of the intervention program. Discussion: This study will be the first cluster randomized controlled trial applied to the investigation of gratitude intervention aimed at improving work engagement among Japanese workers; to promote reciprocal gratitude exchanges within a given organization; and to include both gratitude lists and behavioral gratitude expression. Gratitude interventions have several strengths in terms of implementation: the objectives of the exercises are easy to understand and implement; it does not require much time or expense; they tend to have lower dropout rates; and they do not require experts in psychology. Although implementation difficulties have been common in previous interventions targeting work engagement, gratitude intervention may be suitable even for workers who have limited time to devote to the tasks.