A pragmatic randomized clinical trial of multilevel interventions to improve adherence to lung cancer screening (The Larch Study): Study protocol

Background In real-world settings, low adherence to lung cancer screening (LCS) diminishes population-level benefits of reducing lung cancer mortality. We describe the Larch Study protocol, which tests the effectiveness of two patient-centered interventions (Patient Voices Video and Stepped Reminders) designed to address barriers and improve annual LCS adherence. Methods The Larch Study is a pragmatic randomized clinical trial conducted within Kaiser Permanente Washington. Eligible patients (target n = 1606) are aged 50–78 years with an index low-dose CT (LDCT) of the chest with negative or benign findings. With a 2 × 2 factorial-design, patients are individually randomized to 1 of 4 arms: video only, reminders only, both video and reminders, or usual care. The Patient Voices video addresses patient education needs by normalizing LCS, reminding patients when LCS is due, and encouraging social support. Stepped Reminders prompts primary care physicians to order patient's repeat screening LDCT and patients to schedule their scan. Intervention delivery is embedded within routine healthcare, facilitated by shared electronic health record components. Primary outcome is adherence to national LCS clinical guidelines, defined as repeat LDCT within 9–15 months. Patient-reported outcomes are measured via survey (knowledge of LCS, perception of stigma) approximately 8 weeks after index LDCT. Our mixed-methods formative evaluation includes process data, collected during the trial, and interviews with trial participants and stakeholders. Discussion Results will fill an important scientific gap on multilevel interventions to increase annual LCS adherence and provide opportunities for spread and scale to other healthcare settings.Registration: Trial is registered at clinicaltrials.gov (#NCT05747443).