Identifying lung cancer in Emergency Department patients outside national lung cancer screening guidelines

Background: Lung cancer has become the second most common cancer and the leading cause of cancer death in the United States. We aim to determine factors associated with newly diagnosed lung cancer at the Emergency Department (ED) and identify specific patient populations eligible for lung cancer diagnostic screening. Methods: This is a single-center retrospective observational study. We included all patients aged between 50 and 80 years old, who presented to the ED seeking healthcare between January 1, 2019, and December 31, 2023. Patients' socio-demographics, clinical information, and whether they were eligible for lung cancer screening determined by the United States Preventive Services Task Force (USPSTF) guideline were analyzed and compared between patients who had newly diagnosed lung cancer at ED and those without. Factors associated with newly diagnosed lung cancer patients were determined by multivariable logistic regressions with inverse probability weighting (IPW) to account for observed selection bias of lung cancer screening eligibility. Results: Out of 75,516 patients in this study, 18,641 (25%) patients had documented smoking histories. Among these, only 8,051 (10.66%) were eligible for lung cancer screening, while 18,348 patients received lung computer tomography (CT). Among all patients whose CTs were performed, 123 individuals were identified as having been newly diagnosed with lung cancer. Multivariable logistic regressions showed that the adjusted odds ratio (AOR) for eligible lung cancer diagnostic screening was 3.07 [95% confidence interval (CI): 2.08-4.53, P<0.001] without IPW and 3.49 (95% CI: 2.24-5.42, P<0.001) with IPW. Other factors associated with newly diagnosed lung cancer in ED were older age, female, and patients who spoke neither English nor Spanish. Conclusions: To optimize the identification of suitable patients for lung cancer diagnostic screening in the ED, it may be beneficial to modify the eligibility criteria beyond those currently outlined by the USPSTF guidelines. Integrating additional factors such as advanced age, female sex, and a preference for non-English languages could improve the screening's effectiveness by capturing at-risk populations that might otherwise be overlooked.