Baseline Characteristics of Participants and Pulmonary Nodules in the Watch the Spot Trial: A Pragmatic Trial of Less versus More Intensive Strategies for Active Surveillance of Patients With Small Pulmonary Nodules

Background: Optimal surveillance strategies for patients with small pulmonary nodules are uncertain. The Watch the Spot Trial, a large, cluster-randomized, pragmatic clinical trial, compared less- versus more-intensive strategies for surveillance of patients with incidental or screening-detected nodules ≤15 mm. Methods: We describe between-site variation in methods to identify and enroll patients with small nodules; we used standard measures to describe baseline characteristics of participants and nodules. Results: Participants included a diverse sample of 34,686 individuals who were passively enrolled at one of 14 participating healthcare systems using methods tailored to fit each site. Most patient characteristics were similar between the more- and less-intensive study arms, but participants in the more-intensive arm were more likely to identify as Hispanic/Latino (19.9% vs. 16.5%) or Black (17.8% vs. 10.5%). People who never smoked comprised 35.9% of the sample, and 22.7% of participants had ≥3 comorbidities. Screening-detected nodules were more common in the less-intensive arm (26.2% vs. 14.3%), but arms were balanced for nodule size, lobe, laterality and attenuation. Over 40% of identified nodules measured ≤4 mm in size, while only 14.1% of nodules measured >8 mm. Nodule attenuation and edge characteristics were not described in 36.7% and 74.5% of radiology reports, respectively. Few nodules were noted to be nonsolid (9.5%) or part-solid (3.2%). Conclusions: In a real-world sample of patients with pulmonary nodules measuring ≤15 mm, many nodules were of questionable importance (≤4 mm), and information about nodule attenuation and edge was often not specified by radiologists, representing important opportunities for quality improvement. Clinical Trials Registration: NCT 02623712.