What is the incidence of pneumothorax in patients with asthma overall and in high‑risk subgroups such as children under six years, females, and those with severe or poorly controlled disease?

Pneumothorax Incidence in Asthmatic Patients

The incidence of pneumothorax in asthmatic patients ranges from 0.5% to 2.5% in those admitted with status asthmaticus, with higher rates in specific high-risk subgroups including young children under 6 years, females, and those with severe or poorly controlled disease. 1

Overall Incidence in Asthma

• In hospitalized patients with status asthmaticus, pneumothorax occurs in 0.5-2.5% of cases, making it one of the most concerning complications during acute exacerbation 1
• Pneumothorax was the direct cause of death in 27% of fatal asthma cases in one series, underscoring its clinical significance despite relatively low incidence 1
• Among pediatric asthmatic patients followed long-term, the overall incidence is approximately 0.3%, though this increases substantially in high-risk subgroups 2

High-Risk Subgroups with Elevated Incidence

Children Under 6 Years

• Young children under 6 years have a 1.76-fold increased hazard ratio for pneumothorax compared to non-asthmatic children (95% CI: 1.21-2.57) 2
• The mean age of pediatric asthmatic patients developing pneumothorax is 11.8 years, with a male:female ratio of 1.15:1 3

Female Patients

• Female asthmatic children demonstrate a 2.27-fold increased hazard ratio for pneumothorax compared to non-asthmatic females (95% CI: 1.23-4.16) 2
• This represents a significantly higher risk than the overall asthmatic population 2

Severe or Poorly Controlled Asthma

The incidence escalates dramatically with markers of disease severity:

• Patients with >5 outpatient visits per year have a hazard ratio of 2.81 (95% CI: 1.79-4.42) 2
• Those with >4 emergency department visits per year have a hazard ratio of 1.68 (95% CI: 1.02-2.78) 2
• Patients requiring >4 hospitalization days due to asthma have a hazard ratio of 3.42 (95% CI: 1.52-6.94), representing the highest risk group 2
• The trend test demonstrates statistical significance (P < 0.0001) across all severity markers 2

Clinical Context and Recurrence Patterns

• Pneumothorax occurring during an acute asthma episode is rare and unlikely to recur, with no recurrences reported in one pediatric series of seven patients 4
• In contrast, apparent spontaneous pneumothorax not associated with acute exacerbation has a 83% recurrence rate (5 of 6 patients) when treated conservatively 4
• Asthmatic children overall have a 1.35-fold higher incidence of pneumothorax compared to matched non-asthmatic controls over 12-year follow-up 2

Critical Warning Signs Requiring Immediate Recognition

• Subcutaneous emphysema has 100% positive predictive value for pneumomediastinum in asthmatic patients and should heighten suspicion for air leak syndromes 3
• Mean oxygen saturation is significantly lower in asthmatic patients with pneumomediastinum (90.4% vs 94.1%, P = 0.03) 3
• Chest pain occurs in 27% of asthmatic patients with air leak complications, though this is not statistically different from controls 3
• Tension pneumothorax has even greater fatality potential in high-risk asthmatic patients with chronic severe disease, particularly those with underlying hypoxia or cor pulmonale 5

Important Clinical Caveats

• Routine chest radiography in uncomplicated asthma exacerbation has extremely low yield, with <2% showing pneumonic opacities and 99% showing either normal findings or only hyperinflation 1
• However, chest radiography is essential when pneumothorax or pneumomediastinum is suspected, as these are the most concerning complications 1
• Bilateral simultaneous spontaneous pneumothoraces can occur in asthmatics, though this is exceedingly rare, and requires immediate bilateral needle decompression followed by chest tube placement 6
• Physicians must maintain high clinical suspicion in mechanically ventilated asthmatic patients, as pneumothorax risk increases to 14% during transbronchial procedures in this population 7