220 Chapter 9 Discussion In this trial, we showed that using ULDCT in the diagnostic work-up of patients suspected of non-traumatic pulmonary disease at the ED resulted in functional health outcomes at 28 days that are at least similar to those obtained with management guided by CXR, with minimal differences in ED length of stay, hospital admissions, hospital length of stay, and mortality rates, less additional imaging but more incidental findings. CAP was more often diagnosed at ED discharge, with subsequent confirmation of diagnosis at day28, in the ULDCT group, reflecting the higher accuracy of ULDCT for CAP [1, 2, 5, 6]. However, this hardly affected clinical management. These results are in line with a previous prospective study comparing clinical management and outcomes in adults hospitalized with CAP who had radiological evidence of pneumonia on chestCT but not on CXR, as compared to patients with radiological evidence on CXR. The 66/2251 (2.9%) patients with only evidence of pneumonia on chest-CT had management and clinical outcomes comparable to CXR patients [24]. Similarly, congestive heart failure was more often diagnosed with CXR at day 28. The presumed reason for underdiagnosing congestive heart failure with ULDCT was unfamiliarity of radiologists to detect congestive heart failure on ULDCT in the ED setting. The similarity in health outcomes with CXR and ULDCT, despite the welldocumented lower diagnostic accuracy of CXR [1, 2, 5-7], is likely explained by CXR’s ability to detect the most relevant diagnoses in ED patients [25]. In case a presumed clinical diagnosis is not confirmed by CXR, the attending physician may decide to prompt treatment nonetheless, or perform additional imaging. Indeed, in our study CXR patients underwent significantly more additional imaging procedures within 28 days than in ULDCT patients. As expected, more ULDCT patients had incidental findings and more were in followup because of these findings at 28 days, mostly due to pulmonary nodules. The number of clinically relevant incidental pulmonary nodules and patients in follow-up at day 28 is lower than in previous studies. In a retrospective study of 1000 CT pulmonary angiographies ordered at the ED in a group of patients with an age distribution comparable to our ULDCT cohort, 9.9% of the patients with incidental pulmonary nodules required follow-up, compared to 4.1% in our study (Supplementary Table S2)[26]. This difference is very likely due to differences in comorbidities between both cohorts. The use of computer aided diagnosis for lung nodule detection can aid in the detection and follow-up of clinical relevant incidental pulmonary nodules, especially in the hectic work environment of the ED, but the software was not yet available in the radiology departments during our trial. Further studies should evaluate the added value of artificial intelligence in this setting. The impact of incidental findings on long-term functional health could not be assessed in our trial because of the limited follow-up period. As our study included consecutive ED patients, study limitations are mostly inherent to the demanding workflow at the ED, which sometimes interfered with obtaining informed consent and the logistics to perform ULDCT. Due to the pragmatic nature of this trial, concealment of allocation was not possible. This could have potentially led to information and selection biases. It may explain the higher number of patients with a clinical suspicion of bronchitis for ULDCT and the higher number of patients
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