Temporal and geographical variations of chest x-rays: A ten-year register study from Norway.

Background: Although plain chest x-rays (CXRs) have become standard examinations in many countries, they vary greatly and are recognized as potentially inappropriate imaging procedures. Purpose: To enhance the safety, quality, effectiveness, and efficiency of healthcare services, by providing knowledge of the temporal and geographical variations in the use of CXRs. Materials and methods: Outpatient and inpatient data for CXRs was collected for Norway for the years 2013-2022. Data included patients' age and sex, NCRP code, examination name, modality, hospital/imaging centre, and whether they were in- or outpatients. Results: On average 648,005 CXRs were performed per year in Norway. This amounts to 123 CXRs per 1000 persons per year (2022). 92% of the examinations were performed at public hospitals, and 39% were outpatient examinations. There was a 17% reduction in CXRs from 2013 to 2022. More male than female patients (54%) got a CXR, especially for the age years 60-79. Geographical variations with a factor of 3.7 and 4.7 were observed for inpatient and outpatient examinations, respectively. The differences between catchment areas decreased from 2013 to 2022. Conclusions: This is the first study of the number of CXRs from a whole nation for as long as 10 years. It documents substantial geographical variations in number of examinations and a temporal reduction in the total number of examinations. Information of the temporal and geographical variations is crucial for addressing the issue of appropriate imaging and to increase the safety, quality, effectiveness, and efficiency of the healthcare services.