CT sinus imaging utilization in Norway: trends over time and variation by region, age, and sex.

BACKGROUND: Computed tomography (CT) of the sinuses is a standard component of radiological diagnostics. CT of the sinuses are often regarded as low-value care owing to their minimal impact on disease management. The aim of this study is to describe geographical and temporal variations in outpatient CT sinus utilisation in Norway from 2013 to 2023. METHODS: Administrative data on outpatient CT sinus performed in Norway between 2013 and 2023 were analysed. Descriptive statistics were performed on both unadjusted and adjusted data. Measures of geographical variation applied were: the coefficient of variation (CV), the extremal quotient (EQ), and the systematic component of variation (SCV). Sex-specific differences were formally examined by comparing female and male rates using Mantel-Haenszel standardised statistical measures. RESULTS: Between 2013 and 2023, the sex- and age-adjusted rates of CT sinus per 10,000 individuals in Norway decreased from 52 to 46. The EQ increased from 2.42 to 3.86, the CV from 26% to 31% and SCV values from 6.10 to 8.76, indicating a high level of geographical variation. The ratio of female to male for CT sinus is 1.42 (SD ± 0.11). CONCLUSIONS: The decline in CT sinus is partially linked to the coronavirus pandemic and is likely attributable to the 'Choosing Wisely' campaign. Geographical variability, evident from 2013 to 2015 and becoming more pronounced through 2023, indicates differing CT sinus routines across hospital catchment areas in Norway. It is possible that a substantial proportion of examinations conducted on women may constitute low-value care.