Effort–reward imbalance and social support are associated with chronic fatigue among medical residents in Japan

The purpose of this study was to determine the associations of effort–reward imbalance and social support with chronic fatigue among medical residents in Japan. A total of 104 men and 42 women at 14 teaching hospitals participated in this study. Chronic fatigue was measured by the checklist individual strength questionnaire. Effort, reward and overcommitment were determined by the effort–reward questionnaire developed by Siegrist. Social support was determined by a visual analog scale. Sleeping hours for the last 30 days were estimated based on the number of overnight shifts worked, the average number of sleeping hours, and the number of hours of napping during overnight work. Multiple regression analysis was used to examine the multivariate relationship between these variables and chronic fatigue. In both men and women, effort–reward imbalance was positively associated, and higher social support was negatively associated with chronic fatigue. In men, higher overcommitment was positively associated with chronic fatigue. In women, longer sleeping hours was negatively associated with chronic fatigue and an interaction between sleeping hours and social support was found. The adjusted variance in fatigue explained by the exposure variables was 34% in men and 51% in women. The result of this study suggested that it is desirable to take these factors into consideration in the management of chronic fatigue among medical residents.