For large primary spontaneous pneumothorax (PSP), drainage or simple aspiration are the two first-line treatment options. Outpatient ambulatory strategies have a success rate of almost 80% with few complications. New French recommendations suggest that an outpatient strategy should be preferred if an appropriate care network is in place. However, establishing this care network remains the main obstacle to the use of this strategy. Thus, outpatient management of PSP remains rare, which is neither optimal for the patient, with a likely impact on quality of life (QOL) and satisfaction with care, nor for the healthcare system, with increased costs. We hypothesise that outpatient treatment of PSP compared with usual inpatient management could improve quality of care and represent a more efficient, generalisable and sustainable strategy.

In this multicentre, cluster-controlled, randomised interventional study with stepped wedge implementation, patients aged 18–50 presenting to the emergency department (ED) with a first episode of large PSP will be enrolled in seven university hospitals in France. The main objective of this study is to evaluate the impact on changes in QOL of an ambulatory strategy for the management of large PSP in the ED compared with usual inpatient management. The primary outcome is the difference in QOL as measured by SF-36 score, between drain placement and 6 months. Clinical criteria (pulmonary expansion at 6 days, pain, dyspnoea, complications, recurrence), perceived quality of care (satisfaction, patient preference, anxiety) and ease of implementation of the care pathway will also be assessed. A cost-utility analysis will be carried out to evaluate the incremental cost-utility ratio at 1 year, defined as the difference in costs divided by the difference in utility estimated by the EQ-5D scores.

Ethics approval has been obtained by the Comité de Protection des Personnes Nord Ouest III N° 2024-36. Study findings will be disseminated by publication in a high-impact international journal. Results will be presented at national and international emergency healthcare meetings, and participating patients notified of the main conclusions.

This trial is registered with Clinical Trials Registry NCT06471608. The trial protocol and statistical design are fully described in this study protocol. Additional data can be provided on reasonable request to the sponsor. Protocol version: V2.1 - 21/11/2024.