Long waits in the emergency room aren't just an annoyance, they're often dangerous. That's the message of a recently published Canadian study. The longer a patient had to wait in the emergency room before seeing a doctor, the more likely they were to be admitted to the hospital or die within the next week.

The problem doesn't seem to be due to patients not being treated quickly enough. It seems more a consequence of overcrowded or understaffed emergency rooms leading to poor diagnosis and treatment.

For every additional hour a patient waited to be seen, their risk of death rose by 71-79% and risk of hospital admission rose by 66-95%. The lower numbers are for patients who were initially evaluated as low-risk when seen by the department nurse (triaged); the higher numbers are for those who were initially assessed as high-risk.

The problem doesn't seem to be due to patients not being treated quickly enough. It seems more a consequence of overcrowded or understaffed emergency rooms leading to poor diagnosis and treatment when patients finally do get to see a doctor. Crowded emergency rooms don't give doctors the time to do their job well — they're bad medicine.

The researchers estimate that cutting this wait by one hour would have lowered deaths by 6.5% in the high-risk group and 12.7% in the low-risk group.

The good news from the study is that patients who went home without ever seeing a doctor fared no worse than those who were seen and discharged. These untreated patients have long been thought be at greater than average risk for adverse events, but showed no greater frequency of death or hospitalization in the next seven days than other the patients in the study. Of course, not everyone looks at people seeking medical care and not getting it as good news.

The researchers suggest that observation periods that are too short, reluctance by doctors to order time consuming tests and inadequate doctor-patient communication may all play a part.

The study looked at nearly five years of emergency department visits in high volume emergency rooms in Ontario. It only looked at patients who were discharged (sent home) after seeing a doctor or who left without seeing a doctor at all. These accounted for about 90% of all visits. It did not include patients who were admitted to the hospital as a result of their visit.

The number of patients who died in the next seven days or were admitted to a hospital was then tracked separately for both groups.

Because the study was of patients who were treated and eventually sent home, it implies that they were given treatment that was thought to be adequate but actually was not. The researchers suggest that observation periods that are too short, reluctance by doctors to order time consuming tests and inadequate doctor-patient communication may all play a part in long waiting times leading to poor treatment. The long wait itself, while clearly annoying to patients, is not the primary problem.

The study looked at nearly 14,000,000 patients who were seen by a doctor and later discharged between April 2003 and March 2008. An additional 617,000 patients (about 3.6% of all visits) either left after being evaluated by a nurse but before seeing a doctor or were never evaluated at all. Length of stay in the emergency department was not determined for each individual patient; average length during a shift was used for all patients visiting during that shift.

Complexities aside, the study offers evidence that long waits in the emergency room are themselves a medical emergency.

An article on the study was published online by the British Medical Journal (BMJ) June 1, 2011 and is freely available.