Prevalence and variables associated with solitary pulmonary nodules in a routine clinic-based population: A cross-sectional study

Objective: To determine the prevalence of solitary pulmonary nodules (SPNs) in chest radiology studies and patient's features associated with malignancy in a non-high-risk clinical population. Methods: Patients ≥35 years were referred for thoracic imaging in two hospitals (2010-2011). Eight radiologists determined the presence and characteristics of SPN. Selected variables were collected from radiological register and medical records. Observer agreement in the diagnosis of SPN was assessed. Results: 25,529 patients were included: 23,102 (90.5 %) underwent chest radiograph and 2,497 (9.5 %) a CT. The prevalence of SPN was 2.1 % (95 % CI 1.9 - 2.3) in radiographs and 17.0 % (95 % CI 15.5 - 18.5) in CT. In patients undergoing chest radiograph, detection of SPN with an irregular border was more frequent among smokers. In patients who had a CT, larger SPNs appeared to be associated with 60 years of age or over, diagnosis of a respiratory illness, or male gender. In addition, an irregular border was also more common among men. Conclusions: The prevalence of SPNs detected by both radiograph and CT was lower than that shown in screening studies. Patient characteristics such as age, sex, respiratory disease, or smoking habit were associated with nodule characteristics that are known to be related with malignancy. Key Points: • There is a lower SPN prevalence in the clinical population than in screening studies. • SPN prevalence is associated with some patient characteristics: sex, age, imaging test. • Nodule characteristics related to malignancy were associated with some patient characteristics. © 2014 The Author(s).