Trends in the Incidence of Pulmonary Nodules in Chest Computed Tomography: 10-Year Results from Two Dutch Hospitals

Purpose: To study trends in the incidence of reported pulmonary nodules in chest computed tomography (CT) since 2008. Methods: We retrospectively collected the radiology reports from chest CT studies performed between 2008 and 2019 from the hospital information systems of two large Dutch hospitals. Cases were included between 2008 and 2017; two years served as follow-up. A natural language processing algorithm was used to identify studies with any reported pulmonary nodule measuring up to 3 cm in diameter. Results: Between 2008 and 2017, a total of 68,656 patients underwent 142,111 chest CT examinations at both hospitals combined. The number of annual chest CT scans increased from 11,315 in 7,861 patients to 18,511 in 12,565 patients during this period, an increase of 64%. The percentage of patients, in whom nodules were reported, increased from 33% (2,605 individuals) in 2008 to 50% (6,253 individuals) in 2017. The proportion of these patients who received a follow-up chest CT increased from 911/2,605 (35%) to 2,792/6,253 (45%). The average number of follow-up scans per patient remained similar (1.58 in 2008; 1.64 in 2017). Conclusion: The number of patients who underwent chest CT examinations substantially increased over the past decade. The proportion of patients in whom a pulmonary nodule has been found significantly increased, as did the percentage of those who received follow-up CT. These findings underline that effective nodule management becomes an increasingly important public health issue. Limitations: CT scans that only contain portions of the lungs (e.g. abdominal CT) were not included. Ethics committee approval: This study was approved by the medical ethical review boards of both institutions. Funding for this study: Junior Researcher grant from the Radboud Institute for Health Sciences, Radboudumc, Nijmegen, the Netherlands.