Temporal Patterns of Air Leak Resolution in Secondary Spontaneous Pneumothorax: A Hazard Function Analysis for Optimal Intervention Timing.

: This study was aimed to identify risk factors for persistent air leak after chest tube placement for secondary spontaneous pneumothorax and to determine the optimal timing of treatment. : We retrospectively analyzed 221 cases of secondary spontaneous pneumothorax in patients aged ≥50 years who were treated with chest tube drainage. Patients were categorized into the observation group or additionally treated group based on whether they received interventional treatment beyond chest tube drainage. Air leak resolution patterns were analyzed using hazard function analysis. Risk factors were evaluated using univariate and multivariate analyses. : Hazard function analysis revealed that the probability of air leak resolution decreased by approximately 50% within the first 5 days after the initiation of chest tube drainage, with only 33% of cases resolving by day 7. Beyond days 7-10, resolution probability stabilized at a minimal level. Multivariate analysis identified previous pneumothorax history (HR: 0.422, = 0.007) and low geriatric nutritional risk index (GNRI) (HR: 2.521, < 0.001) as significant independent risk factors for persistent air leak. Further analysis of early resolution (within 7 days) identified female sex (HR: 0.24, = 0.003), absence of previous pneumothorax (HR: 0.21, = 0.003), and higher GNRI values (HR: 1.04, = 0.008) as positive predictors. : Risk stratification based on pneumothorax history and nutritional status enables the optimization of the timing of intervention for persistent air leak. We recommend considering additional treatment between days 7 and 10 of chest tube drainage, with earlier intervention for high-risk patients. This approach may improve patient outcomes while avoiding unnecessarily prolonged conservative management.