Objectives & Background Emergency department crowding is recognised as a major public health problem. While there is agreement that emergency department crowding harms patients, there is less agreement about the best way to measure emergency department crowding. We have previously derived an eight point measure of emergency department 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 emergency departments in England. We conducted independent observations of the measure and compared this to senior clinician's perceptions of crowding and safety (see tables 1 and 2).

Results We obtained 84 measurements, spread evenly across the four emergency departments. 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 Receiving Operator Curve was 0.80 (95% CI 0.72–0.90) for predicting crowding and 0.74 (95% CI 0.60–0.89) for predicting danger. The optimal number of violations for predicting crowding was three, with a sensitivity of 91.2 (95% CI 85.1–97.2) and a specificity of 100.0 (92.9–100). The measure predicted clinician concerns better than individual variables such as occupancy.

Conclusion The ICMED is easily to collect in multiple emergency departments with different IT 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.