Risk factors for the onset of pneumothorax in idiopathic pulmonary fibrosis

Pneumothorax is a serious complication in patients with idiopathic pulmonary fibrosis (IPF). This study aimed to clarify the clinical course of and risk factors for pneumothorax in patients with IPF.

This was a retrospective, cohort study of 164 patients with IPF diagnosed based on relevant guideline criteria. The clinical course of patients with pneumothorax was summarized, and risk factors for pneumothorax were assessed using Fine-Gray proportional hazards model analysis with time-dependent covariates.

Of the 164 patients, 30 (18.3 %) developed pneumothorax. Of the 30 patients with pneumothorax, 4 (13.3 %) died in hospital, and the median duration of chest tube insertion was 11 (6-17.5) days. Low body mass index (BMI) and upper lobe pleuroparenchymal thickening on high-resolution computed tomography (HRCT) were significantly associated with pneumothorax onset (hazard ratio [HR] = 0.85 and 2.55; 95 % confidence interval [CI]: 0.73-0.98 and 1.14-5.73; P = 0.031 and 0.023, respectively). In patients who had repeat pulmonary function tests 6-18 months after diagnosis, annual reduction rates of forced vital capacity (FVC) and diffusing capacity of the lungs for carbon monoxide (DLCO) were significantly associated with pneumothorax onset (HR = 0.97 and 0.97; 95 % CI: 0.93-1.00 and 0.94-0.99; P = 0.034 and 0.013, respectively).

Pneumothorax is a serious event having a poor prognosis and requiring long-term treatment in patients with IPF. Low BMI, upper lobe pleuroparenchymal thickening on HRCT, annual FVC reduction rates, and annual DLCO reduction rates are associated with the onset of pneumothorax in patients with IPF.