Rate of Secondary Pneumothorax in Lung Disease
Secondary pneumothorax occurs at a combined hospital admission rate of 5.8-16.7 per 100,000 per year for all causes, with COPD being the most common underlying lung disease responsible for secondary pneumothorax (accounting for approximately 70% of cases), while cystic fibrosis represents a less common but clinically significant cause. 1, 2
Epidemiological Data
Overall Incidence Rates
Combined primary and secondary pneumothorax hospital admission rates in the UK are reported at 5.8 per 100,000 per year for women and 16.7 per 100,000 per year for men 1
Mortality rates for all spontaneous pneumothorax (primary and secondary combined) in the UK were 0.62 per million per year for women and 1.26 per million per year for men between 1991 and 1995 1
Disease-Specific Patterns
COPD represents the dominant underlying cause of secondary spontaneous pneumothorax:
In a large retrospective study from southern China, COPD accounted for 69.7% of all secondary spontaneous pneumothorax cases, followed by tuberculosis at 16.5% 2
Secondary pneumothorax patients with COPD demonstrate significantly different clinical characteristics compared to primary pneumothorax, with symptoms typically out of proportion to pneumothorax size 1
Cystic fibrosis is mentioned as an underlying lung disease associated with secondary pneumothorax, though specific incidence rates are not provided in the available guidelines 3, 4
Clinical Significance and Risk Factors
Prognostic Factors
Patient characteristics that increase recurrence risk in secondary pneumothorax include 2:
- Taller height
- Lower body weight
- Presence of underlying lung disease (secondary vs. primary pneumothorax)
Mortality Considerations
Secondary pneumothorax carries substantially higher mortality risk than primary pneumothorax:
Arterial PaO₂ was below 7.5 kPa (55 mm Hg) and PaCO₂ above 6.9 kPa (50 mm Hg) in 16% of secondary pneumothorax cases 1
In COPD patients with coexisting pulmonary fibrosis and emphysema, the mortality rate from respiratory failure during follow-up was significantly higher (6/7 patients, 85.7%) compared to emphysema alone (11/51 patients, 21.6%) 5
Postoperative mortality in patients with pulmonary fibrotic diseases undergoing surgical treatment for secondary pneumothorax was 21.4%, compared to only 1.4% in COPD patients 6
Clinical Presentation Differences
Secondary pneumothoraces present with more severe symptoms than primary pneumothoraces 1:
Most patients with secondary pneumothorax complain of breathlessness that is out of proportion to the size of the pneumothorax 1
Clinical symptoms are generally more severe in secondary compared to primary pneumothorax, requiring more aggressive intervention 1
Arterial blood gas measurements show PaO₂ less than 10.9 kPa (80 mm Hg) in 75% of all pneumothorax patients, with more severe hypoxemia in those with underlying lung disease 1
Management Implications
The presence of underlying lung disease fundamentally changes treatment approach 1:
Observation alone is only recommended for secondary pneumothoraces less than 1 cm depth or isolated apical pneumothoraces in asymptomatic patients, with hospitalization required 1
Simple aspiration success rates are significantly lower in secondary pneumothorax (33-67%) compared to primary pneumothorax (59-83%) 1
Age significantly impacts aspiration success: patients under 50 years show 70-81% success, while those over 50 years show only 19-31% success 1