Contralateral Recurrence and Temporal Trend After First Side Surgery for Primary Spontaneous Pneumothorax: A Multicenter Analysis

Background: Contralateral recurrence following surgically treated primary spontaneous pneumothorax represents clinical concern yet remains poorly understood. This study aims to expand the current understanding by evaluating a large, multicenter cohort over a 10-year period and to determine the true incidence of contralateral recurrence assessing the potential role of clinical factors in risk stratification. Methods: A total of 479 patients surgically treated for PSP (2012–2024) across three Italian high-volume centers were retrospectively reviewed. Secondary pneumothorax, patients <18 years old, lung emphysema or intraparenchymal large bullae, and the thoracotomy approach were excluded. The association between categorical variables and contralateral recurrence was assessed using the chi-square (χ2) test, while the association with continuous variables was evaluated using the t-test. Time to recurrence was analyzed using Kaplan–Meier survival curves. Variables with a p-value < 0.05 were considered statistically significant. Results: We identified 59 patients who experienced contralateral recurrence: 45 were males, the mean age was 26.66 ± 12.32 and the mean BMI was 22.00 ± 2.92; only 13 were active smokers. Age (p < 0.001) and smoking history (p = 0.029) were significantly associated with contralateral recurrence in univariate analysis, though these were not confirmed in multivariate analysis. Among the cohort of recurrence, 53 patients only had a recurrence on the contralateral side, with a median time to recurrence of 139 days. The incidence rate ratio (IRR) of recurrence for patients with a mean age of < 34 years was 1.23, which translates to a 23% increased risk. No significant impact of age (p = 0.25), sex (p = 0.67), or smoking (p = 0.59) on the time to recurrence on the other side was observed through Kaplan–Meier analysis. The peak incidence for the first episode of PNX surgically treated and contralateral recurrence was observed in October, November and January. Conclusions: This study highlights a 12% contralateral recurrence rate after PSP surgery. Younger age is associated with earlier contralateral recurrence. Seasonality may influence recurrence patterns. Further studies should explore underlying mechanisms and preventive strategies.