Impact of night float system on improving residents' work hours

Abstract

This study aimed to investigate whether introduction of a night float (NF) system changed residents' working conditions. A first in Japan, in 2017 the NF system was introduced at our institution. We retroactively compared first and second year residents' working hours between 2016 and 2017. The primary end point was weekly work hours of general internal medicine (GIM) rotators versus NF residents. Secondary endpoints were shifts of over 32 continuous hours, and more than 60 working hours/week. We compared these points before and after the introduction of the NF system. Median weekly working hours was 86 hours 56 minutes for GIM rotators in 2016, 88 hours 47 minutes for GIM rotators in 2017 (p=0.2), and 58 hours 10 minutes for the NF team (p<0.001). There were fewer instances of residents working more than 32 hours continuously in 2017 compared to 2016 (p<0.001), and there were no such occurrences in the NF team. There was also reduced instance of 60-plus hour weeks in the NF team compared to 2016 and 2017 GIM rotators. These results suggest that there was an improvement in residents' working hours in the NF team compared to GIM rotators. Moreover, introducing a NF system resulted in fewer 32-plus hour continuous shifts and 60-plus hour weeks, and overall improvement of residents working conditions.