Initial validation of the International Crowding Measure in Emergency Departments (ICMED) to measure emergency department crowding

Abstract

Introduction Emergency department (ED) crowding is recognised as a major public health problem. While there is agreement that ED crowding harms patients, there is less agreement about the best way to measure ED crowding. We have previously derived an eight-point measure of ED crowding by a formal consensus process, the International Crowding Measure in Emergency Departments (ICMED). We aimed to test the feasibility of collecting this measure in real time and to partially validate this measure. Methods We conducted a cross-sectional study in four EDs in England. We conducted independent observations of the measure and compared these with senior clinician's perceptions of crowding and safety. Results We obtained 84 measurements spread evenly across the four EDs. The measure was feasible to collect in real time except for the 'Left Before Being Seen' variable. Increasing numbers of violations of the measure were associated with increasing clinician concerns. The area under the receiver operating characteristic curve was 0.80 (95% CI 0.72 to 0.90) for predicting crowding and 0.74 (95% CI 0.60 to 0.89) for predicting danger. The optimal number of violations for predicting crowding was three, with a sensitivity of 91.2 (95% CI 85.1 to 97.2) and a specificity of 100.0 (92.9-100). The measure predicted clinician concerns better than individual variables such as occupancy. Discussion The ICMED can easily be collected in multiple EDs with different information technology systems. The ICMED seems to predict clinician's concerns about crowding and safety well, but future work is required to validate this before it can be advocated for widespread use.

Effects of emergency department crowding on the delivery of timely care in an inner-city hospital in the Netherlands

“…Second, we used a crude measure of crowding: ED occupancy ≥100%. More sophisticated crowding measures such as the International Crowding Measure in Emergency Departments [25] and the National Emergency Department Overcrowding Score [26] are not available in our setting.…”

Comparison of the International Crowding Measure in Emergency Departments (ICMED) and the National Emergency Department Overcrowding Score (NEDOCS) to measure emergency department crowding: pilot study

“…Where observations are taken close together, sample sizes may need to be substantially increased to account for the temporal correlation. There are also implications for the interpretation of existing studies, and this methodological finding invalidates some of our own previous work 19. Extreme caution should be applied when drawing inferences based on naive treatment of observations which are likely to be correlated in time.…”

“…Seven of the eight measures are recordable in real time; however, the ‘left before treatment’ measure cannot easily be recorded in real time but is best reported historically. The ICMED in the real-time data collection 7-measure format has been partially validated and shows good discriminant and face validity 19. We now propose that, for real-time measurement of crowding, the 7-measure format of ICMED be used and referred to as short International Crowding Measure (sICMED) in emergency departments.…”

Prevalence of Crowding, Boarding and Staffing Levels in Swedish Emergency Departments - a National Cross Sectional Study

“…Occupancy rate is a simple numeric variable that accounts for the core resource, an ED treatment bed. Staff perception of crowding or workload has been used to derive the International Crowding Metric in Emergency Departments (ICMED), National Emergency Department Overcrowding Score (NEDOCS) and Swedish Emergency Department Assessment of Patient Load (SEAL), but is less studied outside these scores [19][20][21]. Workload is subjective in nature, but has face validity as a measure of human resource utilisation and may complement occupancy rate at times when available treatment beds does not re ect crowding.…”