2016 Volume 82 Issue 2 Pages 73-82
The purpose of this study was to investigate whether the number of patients examined could be a useful indicator of workload influencing natural killer cell activity (NKCA) among Japanese emergency physicians (EPs). The subjects were 34 healthy EPs from six critical care emergency centers in Japan. They completed a questionnaire regarding their workload and provided blood samples at the beginning and end of work shift for the measurement of NKCA in 2005. The subjects stayed at the hospital from the morning to the following evening for approximately 32 continuous hours. Relative to residents, staff members examined a significantly greater number of seriously ill inpatients (p＜0.01). NKCA at the end of shift was significantly lower than the beginning of shift among staff members (p＜0.01), while no significant change was observed among residents. Multiple linear regression analysis (stepwise method), using change in NKCA as a dependent variable, showed that the number of seriously ill inpatients examined was the only workload factor significantly associated with change in NKCA (standard partial regression coefficient＝-0.59, p＜0.01). Additionally, the confounding factor of sex was significantly associated with change in NKCA (standard partial regression coefficient＝-0.33, p＝0.04). The results suggested that physiciansʼ NKCA may be affected by the number of seriously ill inpatients they examined, although circadian rhythm and sex may confound this relationship; thus, number of seriously ill patients may serve as an indicator of workload in Japanese EPs.