Reduced Functional Bed Capacity Due to Inpatient Boarding Is Associated with Increased Rates of Left Without Being Seen in the Emergency Department.

INTRODUCTION: We evaluated the relationship between inpatient boarding, measured as functional bed capacity, and left-without-being-seen (LWBS) rates. Functional bed capacity is defined as the mean percentage of ED beds available for new and existing patients over a 24-hour period. METHODS: We performed quantile regression models examining the association between LWBS and terciles (low, medium, and high) of functional bed capacity, as well as median admit-to-departure times, controlling for other daily operational metrics. We additionally performed an encounter-level analysis to assess the relationship between functional bed capacity at the time of a patient's arrival and their likelihood of LWBS. Study sites included one academic, one community, and one pediatric ED in a single, urban medical system. RESULTS: Our study included 373,388 visits. In the adjusted regression at the daily level, low functional bed capacity was associated with an increase of 1.59% in LWBS compared to high functional bed capacity, which represented a 26.5% relative increase (about three patients) compared to median LWBS of 6.0% (P < .001). Larger daily census (+ 0.07% for each additional patient, P <.001), resulted in two additional patients LWBS for every 15-patient increase in daily census from the median. Additionally, longer length of stay of discharged patients (+ 0.05% for each minute increase, P < .001), resulted in two additional patients LWBS for every 20-minute increase in length of stay from the median. Weekdays relative to weekend days were associated with a 1.28% decrease in LWBS (P < .001) (approximately three fewer patients who left without being seen relative to the median LWBS of 6.0%). At the encounter level, functional bed capacity in the low and middle tercile was significantly associated with an increased probability of a patient LWBS (91% and 40% increases, respectively, P < .001). Of the patients who LWBS, 9.3% were high acuity, 59.5% medium acuity, and 31.2% low acuity. CONCLUSION: Functional bed capacity is a new and pragmatic operational metric strongly associated with left-without-being-seen rates and provides an improved way to measure, study, and communicate the impact of inpatient boarding. We propose using functional bed capacity as a metric in future studies of ED operations. Additional studies that incorporate staffing levels to more accurately approximate functional bed capacity and better characterize its true impact on LWBS rates are needed.