Association of Operative Day of the Week with the Length of Stay and Total Hospitalization Costs in Patients with Partial Mastectomy: A Nationwide Database Study in Japan

INTRODUCTION: Length of stay (LOS) is a major concern while optimizing medical resources and costs. Hence, factors influencing LOS should be investigated. In Japan, breast cancer surgery generally involves several days of hospitalization for observation, despite few complications. We hypothesized that the day of surgery (weekday; Monday-Friday) affects LOS. METHODS: Using a Japanese nationwide database, we retrospectively identified 146,610 patients who underwent partial mastectomy for stage 0-III breast cancer from July 2010 to March 2017. We conducted multivariable linear and logistic regression analyses adjusting for background characteristics (such as comorbidities and hospital characteristics) with a generalized estimating equation for within-hospital clustering to compare postoperative and total LOS, total hospitalization costs, and postoperative complications between the groups for whom the surgery was performed on different days of the week. RESULTS: In total, whereas the median postoperative LOS was 4 days (interquartile range, 3-6 days), the median total LOS was 6 days (5-8 days). The median total hospitalization cost was 6,189 US dollars (5,609-6,668 US dollars), and postoperative complications occurred in 3.3% of cases. Despite no significant difference in postoperative complications, Monday-Wednesday surgeries showed significantly shorter postoperative LOS than Friday surgeries (−0.11 days [95% confidence interval, −0.14 to −0.07] on Monday with reference to Friday). Nevertheless, Monday surgeries showed significantly increased total LOS (0.69 days [0.64-0.74]) and hospitalization costs (93 US dollars [71-116]) in comparison with Friday surgeries. CONCLUSIONS: The operative day of the week was associated with increased LOS and cost, with no difference in postoperative complications after partial mastectomy. Surgeries on Monday involved longer preoperative hospital stays and higher total hospitalization costs than those on other weekdays.