LAUSR

Supplemental Digital Content is available in the text. Objective A new nationwide guideline for minor head injury was introduced in the Netherlands in 2010. The effect on computed tomography (CT) ratio and hospital admission ratio after introduction of the guideline is unknown. The aim was to reduce these numbers as part of cost-effective health care. Therefore, we assessed the effect on these variables after introduction of the guideline. Methods We used an interrupted time-series study design. Data selection was done 3 years before (2007–2009) and several years after (2012, 2014, 2015) introduction of the guideline. Results Data collection was performed for 3880 patients. Introduction of the new guideline was associated with an increase in CT ratio from 24.6% before to 55% after introduction (P < 0.001). This increase is the result of both the new guideline and a secular trend. Besides this, hospital admissions increased from 14.7 to 23.4% (P < 0.001) during the study period. This increase was less clearly associated with the new guideline. After introduction of the guideline there was no significant difference in (intra)cranial traumatic findings (2.6% vs. 3.4%; P = 0.13) and neurosurgical interventions (0.1% vs. 0.2%; P = 0.50). Conclusion Between 2007 and 2015, a marked increase in CT ratio and hospital admissions has been observed. The increase in CT ratio seems to be caused both by the new guideline and by a secular trend to perform more CT scans. Adaptations to the guideline should be considered to improve patient care and cost-effectiveness in patients with minor head injury.