Utilisation and time to performance of diagnostic imaging in patients admitted to Danish emergency departments: a nationwide register-based study from 2007 to 2017.

Objectives: To describe the development of diagnostic imaging utilisation in Denmark from 2007 to 2017, coinciding with a major national reform of the emergency healthcare system.

Design: Nationwide descriptive register-based study.

Setting: All public hospitals in Denmark.

Participants: All unplanned hospital contacts ≥18 years old at somatic hospitals in Denmark from 1 January 2007 to 31 December 2017.

Primary And Secondary Outcome Measures: The primary outcome measure was the probability of having CT, X-ray, MRI or ultrasound performed during hospitalisation in 2017 compared with 2007. The secondary outcome measure was receiving diagnostic imaging within 4 hours of hospitalisation.

Results: The probability of having a radiological examination during unplanned hospital admission increased from 2007 to 2017 (CT: 3.5%-10.3%; MRI: 0.2%-0.8%; ultrasound: 2.3%-4.5%; X-ray: 23.8%-26.8%). For CT scan, the adjusted OR was 3.09 (95% CI: 2.73, 3.51); for MRI, the adjusted OR was 3.39 (95% CI: 1.87, 6.12) and for ultrasound, the adjusted OR was 1.93 (95% CI: 1.56, 2.38). The likelihood of having the examination within the first 4 hours in the hospital increased from 2007 to 2017. For X-ray, the adjusted OR was 1.39 (95% CI: 1.07, 1.56); for CT scan, the adjusted OR was 1.35 (95% CI: 1.16, 1.59); for MRI, the adjusted OR was 1.34 (95% CI: 1.09, 1.66) and for ultrasound, the adjusted OR was 1.38 (95% CI: 1.16, 1.64).

Conclusion: This nationwide study describes the development of diagnostic imaging utilisation in Denmark from 2007 to 2017. The probability of receiving radiological examinations during unplanned hospitalisation increased over this period, and the time from hospital contact to performance decreased. This supports the notion that enhancement in radiological equipment will also lead to more frequent and faster utilisation.