Wide variation and rising utilization of stroke magnetic resonance imaging: data from 11 states.

OBJECTIVE

Neuroimaging is an essential component of the acute stroke evaluation. Magnetic resonance imaging (MRI) is more accurate than computed tomography (CT) for the diagnosis of stroke, but is more costly and time-consuming. We sought to describe changes in MRI utilization from 1999 to 2008.

METHODS

We performed a serial cross-sectional study with time trends of neuroimaging in patients with a primary International Classification of Diseases, 9th Edition, Clinical Modification discharge diagnosis of stroke admitted through the emergency department in the State Inpatient Databases from 10 states. MRI utilization was measured by Healthcare Cost and Utilization Project criteria. Data were included for states from 1999 to 2008 where MRI utilization could be identified.

RESULTS

A total of 624,842 patients were hospitalized for stroke in the period of interest. MRI utilization increased in all states. Overall, MRI absolute utilization increased 38%, and relative utilization increased 235% (28% of strokes in 1999 to 66% in 2008). Over the same interval, CT utilization changed little (92% in 1999 to 95% in 2008). MRI use varied widely by state. In 2008, MRI utilization ranged from a low of 55% of strokes in Oregon to a high of 79% in Arizona. Diagnostic imaging was the fastest growing component of total hospital costs (213% increase from 1999 to 2007).

INTERPRETATION

MRI utilization during stroke hospitalization increased substantially, with wide geographic variation. Rather than replacing CT, MRI is supplementing it. Consequently, neuroimaging has been the fastest growing component of hospitalization cost in stroke. Recent neuroimaging practices in stroke are not standardized and may represent an opportunity to improve the efficiency of stroke care.