The aim of this study was to compare the effectiveness of chest X-ray to that of thoracic computed tomography (CT) for the detection of the causes of secondary spontaneous pneumothorax (SP).

A prospective cohort of patients with SP was studied. All chest X-ray and CT examinations of the patients were reviewed retrospectively by an expert radiologist blinded to clinical data. The concordance between the CT examination and chest X-ray was assessed using the Cohen Kappa coefficient (κ), based on a bootstrap resampling method.

A total of 105 patients with SP were included. There were 78 men and 27 women, with a mean age of 34.5 years±14.2 (SD) (range: 16–87 years). Of these, 44/105 (41%) patients had primary SP and 61/105 (59%) had secondary SP due to emphysema (47/61; 77%), tuberculosis (3/61, 5%), lymphangioleiomyomatosis (3/61; 5%), lung cancer (2/61, 3%) or other causes (6/61; 10%). Apart from pneumothorax, CT showed abnormal findings in 85/105 (81%) patients and chest X-ray in 29/105 (28%). Clinically relevant abnormalities were detected on 62/105 (59%) CT examinations. The concordance between chest X-ray and CT was fair for detecting emphysema (κ=0.39; 95% CI: 0.2420–0.55), moderate for a mass or nodule (κ=0.60; 95% CI: 0.28–0.90), fair for alveolar opacities (κ=0.39; 95% CI: −0.02–1.00), and slight for interstitial syndrome (κ=0.20; 95% CI: −0.02–0.85).

Chest X-ray is not sufficient for detecting the cause of secondary SP. As the detection of the cause of secondary SP may alter the therapeutic approach and long-term follow-up in patients with SP, the usefulness of a systematic CT examination should be assessed in a prospective trial.