Close to a third of emergency departments closed shop over the last two decades, a new study shows.

Between 1990 and 2009, the number of hospital emergency departments in non-rural areas in the USA declined by 27%, according to a study in Wednesday’s Journal of the American Medical Association.

‘That’s a hefty number, and more than I expected,’ says study author Renee Hsia, an assistant professor of emergency medicine at the University of California, San Francisco.

Hsia says she and colleagues did a ‘survival analysis,’ much like researchers do for breast cancer patients. ‘In our study, we used the ER as the patient,’ says Hsia.

They found that the number of emergency departments dropped from 2,446 to 1,779 - an average of 89 closings per year. The figure included only non-rural locations since those in rural areas generally receive special funding from federal sources.

Hsia says researchers also wanted to examine the factors that led to closings. ‘Certain hospitals are at higher risk for losing their ERs than others,’ she says. ERs shut down were more likely to: