Spontaneous Pneumothorax (SP) in COVID-19 Is Associated With Worse Outcomes Than SP in Non-COVID-19 Patients, Which Suggests That SP in COVID-19 is a Sign of Disease Severity

To the Editor:

We read with great interest the recent article in CHEST (March 2021) by Miró et al¹ who concluded that spontaneous pneumothorax (SP) is associated with worse outcomes than SP in patients without COVID-19 and in patients with COVID-19 without SP. We would like to comment. When we look carefully to the results, we see that 32.3% of the patients with COVID-19 with SP went to ICU and that patients died significantly more with an OR of 4.07.¹ Compared with the control group that did not have COVID-19 with SP, the ICU admission was only 2.6%, and the mortality rate was 1.6%. Compared now with COVID-19 without SP, ICU admission was only 1.8%, and the mortality rate was 13.8%.¹ Clearly, the two control groups were much less sick when we see the ICU admission compared with COVID-19 with SP. So, there is no certainty that SP is a sign of higher severity on itself because it might be just a pure association and not a strong relationship. Indeed, the difference in severity might be due to other comorbidities not described in the study. The literature is very controversial regarding the mortality rate and this potential relationship. In a study looking at 15 cases of COVID-19, spontaneous pneumomediastinum was associated with a much lower mortality rate of 26%.² In another cohort study with 18 patients with SP, the mortality rate was only 27%.³ In another review, the authors concluded that it should be emphasized that a causal relationship between COVID-19 severity and pneumothorax cannot be concluded.⁴ The presence of prior bullous disease, underlying connective tissue disease, hormonal irregularities, environmental exposure, and vigorousness of coughing are unknown considerations.⁴ The majority of these precipitating factors were not evaluated in the study of Miro et al.¹ In addition, when comparing COVID-19 with SP with COVID without SP, we found that history of asthma was significantly higher (20% vs 6.8%) as was dyspnea (87.5% vs 54.3%), which are well-known precipitating factors for SP. Regarding the severity of the disease between COVID-19 with SP compared with COVID-19 without SP, classic severity indicators for COVID-19 were not different between the two groups, such as C-reactive protein levels, procalcitonin levels, and aspartate amino transferase levels.¹ In a more recent study,⁵ the authors showed the importance early surgical treatment for SP, and we do not know how many of the patients in the study of Miro et al¹ underwent rapid surgery that could save their lives.