Table 1. Systematic review, patient characteristics.

Study (year)	Country	Study type (level of evidence)	Patients, (n)	Gender, male (%)	Age, median (IQR)	Primary disease (n)	Comorbidities
Sciortino et al. (2009)	USA	Case-study (level V)	1	100	70	Secondary spontaneous pneumothorax due to bullous emphysema	None
Byun et al. (2013)	Korea	Case-series (level V)	4	100	73 (69–76)	Secondary spontaneous pneumothorax due to COPD with emphysema	NR
Towe et al. (2014)	USA	Case-study (level V)	1	100	74	Malignancy treated with VATS lobectomy	Coronary disease
Son et al. (2014)	Korea	Case-series (level V)	10	70	Mean 62 (range, 42–81)	Lung surgery-related (1), blunt trauma-related lung laceration (1), ventilator associated barotrauma (5), bronchopleural fistula post-lung transplantation (1), secondary spontaneous pneumothorax (1)	NR
Mihanović et al. (2018)	Croatia	Case-study (level V)	1	100	60	Traumatic pneumothorax (rib fractures with bilateral pneumothorax)	Lung malignancy treated with lobectomy
Sindi et al. (2019)	Saudi Arabia	Case-study (level V)	1	100	7	Traumatic pneumothorax	None
Taylor et al. (2020)	USA	Case-study (level V)	1	0	52	Traumatic pneumothorax (rib fractures with bilateral pneumothorax and pneumomediastinum)	COPD, cardiomyopathy, bipolar disorder
Prakash et al. (2020)	New Zealand	Case-study (level V)	1	100	54	Traumatic pneumothorax	Emphysema, blood dyscrasia, schizophrenia, end-stage liver failure with coagulopathy
Huan et al. (2020)	Malaysia	Case-study (level V)	1	100	80	Secondary spontaneous pneumothorax due to COPD	None
Wezel et al. (2020)	The Netherlands	Case-series (level V)	2	100	(range, 66–75)	Secondary spontaneous pneumothorax due to bullous emphysema (1), secondary spontaneous pneumothorax due to COPD (1)	NR

COPD, chronic obstructive pulmonary disease; IQR, inter-quartal range; NR, not reported; VATS, video assisted thoracic surgery.