Implementing a preauthorization policy can lead to increased utilization of after-hours CT, according to a recent Canadian study published in Academic Radiology. The one exception to that rule, the study said, is some neurological examinations.

Kirsteen R. Burton, department of medical imaging at the University of Toronto, and colleagues studied the effects after-hours CT utilization in the emergency department (EDs) of two Canadian public hospitals for six months before a preauthorization policy was implemented and six months after successful implementation.

Burton et al. explained that the goal of the new policy was to improve the patient’s overall experience at the ED.

“The hypothesis is that a streamlined ordering process for all commonly requested CT ED studies should decrease the length of stay for ED patients who require one of those CT examinations included within the policy,” the authors wrote.

Overall, the team noted a significant increase in the numbers of thorax/abdomen/pelvis examinations (350 more), thorax/abdomen/pelvis angiography examinations (79 more), neuroangiography examinations (149 more), and musculoskeletal examinations (36 more) after implementation.

The number of neurological examinations, on the other hand, decreased more after implementation than any of the other subtypes increased.

“The only category of examination we found to show a significant decrease in ordering frequency was non-neuroangiographic neuroradiological studies,” the authors wrote. “This may be secondary to a potential ‘substitution effect’ wherein the decline in non-neuroangiographic study ordering was offset by an increase in the demand for neuroangiographic studies. The reasons for this substitution, and the degree to which it may explain our results, are a potential topic for future study.”

The authors noted that providers throughout the healthcare industry take the possibility of exposing patients to too much radiation as seriously now as ever before, yet utilization in most exam types still increased after the preauthorization policy was put in place. What could have led to that increase?

“There are a number of hypotheses as to why CT examination utilization may increase over time in spite of increased awareness of the radiation risks of CT examinations and the systemic costs associated with this tool,” the authors wrote. “These include an increase in desire for diagnostic certainty and decrease in tolerance of misdiagnosis, improved availability and speed of CT scanners, and improvements in the diagnostic capabilities of CT technology. The trend is especially concerning given that other authors have shown that increased use of CT examinations by ED physicians does not necessarily lead to improved clinical outcomes.”

Burton and colleagues noted that the same ED physicians worked at both sites where the new policy was implemented. However, they wrote, one limit of their study was that they did not track each physician’s shifts at the two sites, assuming that such numbers would even out over the course of six months.