The outcome and risk factors for recurrence and extended hospitalization of secondary spontaneous pneumothorax.

Purpose: Secondary spontaneous pneumothorax (SSP) is difficult to treat by itself and due to its association with serious underlying diseases. It has a high rate of recurrence and often requires extended hospitalization. Therefore, we evaluated the outcome and risk factors associated with recurrence and extended hospitalization.
Methods: We retrospectively examined 61 patients with SSP, and evaluated the patients' characteristics, underlying diseases, introduction of home oxygen therapy, Brinkman index, and X-ray imaging findings to determine the risk factors for recurrence and extended hospitalization.
Results: There were 28 patients (46.0%) with chronic obstructive pulmonary disease, 8 (13.1%) with interstitial pneumonia, 16 (26.2%) with massive emphysema, and 9 (14.8%) with other diseases. Adhesion and mediastinal shift visualized by X-ray imaging were observed in 37 (37.9%) and 25 patients (40.1%), respectively. Recurrence occurred in 25 patients (40.9%) and the average hospitalization duration was 14.5 days (±11.2). A multivariate analysis showed that adhesion on X-ray imaging was a significant risk factor for recurrence (odds ratio 4.90, 95% confidence interval 1.38-21.44) and mediastinal shift on X-ray imaging was a significant risk factor for extended hospitalization (odds ratio 6.05, 95% confidence interval 1.44-31.06).
Conclusions: Findings from X-ray imaging, and not underlying diseases, are risk factors for recurrence and extended hospitalization.