NEW YORK — The notion that low-acuity patients are an important cause of overcrowding in the emergency department is probably not true, Michael J. Schull, M.D., reported at the annual meeting of the Society for Academic Emergency Medicine.
Administrators, politicians, researchers, and physicians often blame low-acuity patients for worsened ED crowding. Plans to reduce ED overcrowding include diverting low-acuity ED patients to places such as fast-track emergent care centers or primary care clinics.
But it is unknown if low-acuity patients are actually responsible for extended lengths of stay for patients with more acute conditions, said Dr. Schull, an emergency physician at the Institute for Clinical Evaluative Sciences at Sunnybrook and Women's College Health Sciences Centre, Toronto.
He and his colleagues analyzed the assumption that low-acuity patients contribute to ED overcrowding by reviewing consecutive 8-hour intervals in an administrative data set that included all visits to all high-volume EDs in Ontario during 2002–2003. Overall, the investigators analyzed 4.1 million visits to 110 EDs (16 teaching and 94 community) that had patient volumes ranging from 13,000 to 81,000 per year.
He classified high-acuity ED patients as those who were admitted to the hospital and low-acuity patients as those who arrived at the ED under their own power, received a score of 4 or 5 on the Canadian Triage & Acuity Scale, and were later discharged. All other ED patients were medium-acuity patients.
A patient's entire length of stay in the ED was credited to the 8-hour interval in which he or she arrived, even if the stay extended into the next interval.
Dr. Schull did not find that the EDs were able to reduce the collective length of stay of medium- and high-acuity patients any faster when fewer low-acuity patients were present. For every new low-acuity patient, the combined length of stay for medium- and high-acuity patients increased by only 0.6 minutes. Each new high-acuity patient increased the total length of stay for medium- and high-acuity patients by 7 minutes.
“It takes about 12 new low-acuity patients to be equivalent to 1 high-acuity patient” in increasing the length of stay of medium- and high-acuity patients, he said.
During a typical 8-hour interval, a median of 16 new low-acuity patients arrived at an ED, resulting in an average increase in the length of stay of medium- and high-acuity patients of 9.7 minutes (4% increase), which is not clinically significant, Dr. Schull said. A median of three new high-acuity patients arrived at an ED during the 8-hour interval, increasing the mean length of stay of medium- and high-acuity patients by 21 minutes (9%).