Frequency, Risk Factors, Clinical Characteristics, and Outcomes of Spontaneous Pneumothorax in Patients With Coronavirus Disease 2019: A Case-Control, Emergency Medicine-Based Multicenter Study.

<bold>Background: </bold>Recent reports of patients with coronavirus disease 2019 (COVID-19) developing pneumothorax correspond mainly to case reports describing mechanically ventilated patients. The real incidence, clinical characteristics, and outcome of spontaneous pneumothorax (SP) as a form of COVID-19 presentation remain to be defined.<bold>Research Question: </bold>Do the incidence, risk factors, clinical characteristics, and outcomes of SP in patients with COVID-19 attending EDs differ compared with COVID-19 patients without SP and non-COVID-19 patients with SP?<bold>Study Design and Methods: </bold>This case-control study retrospectively reviewed all patients with COVID-19 diagnosed with SP (case group) in 61 Spanish EDs (20% of Spanish EDs) and compared them with two control groups: COVID-19 patients without SP and non-COVID-19 patients with SP. The relative frequencies of SP were estimated in COVID-19 and non-COVID-19 patients in the ED, and annual standardized incidences were estimated for both populations. Comparisons between case subjects and control subjects included 52 clinical, analytical, and radiologic characteristics and four outcomes.<bold>Results: </bold>We identified 40 occurrences of SP in 71,904 patients with COVID-19 attending EDs (0.56‰; 95% CI, 0.40‰-0.76‰). This relative frequency was higher than that among non-COVID-19 patients (387 of 1,358,134, 0.28‰; 95% CI, 0.26‰-0.32‰; OR, 1.93; 95% CI, 1.41-2.71). The standardized incidence of SP was also higher in patients with COVID-19 (34.2 vs 8.2/100,000/year; OR, 4.19; 95% CI, 3.64-4.81). Compared with COVID-19 patients without SP, COVID-19 patients developing SP more frequently had dyspnea and chest pain, low pulse oximetry readings, tachypnea, and increased leukocyte count. Compared with non-COVID-19 patients with SP, case subjects differed in 19 clinical variables, the most prominent being a higher frequency of dysgeusia/anosmia, headache, diarrhea, fever, and lymphopenia (all with OR > 10). All the outcomes measured, including in-hospital death, were worse in case subjects than in both control groups.<bold>Interpretation: </bold>SP as a form of COVID-19 presentation at the ED is unusual (< 1‰ cases) but is more frequent than in the non-COVID-19 population and could be associated with worse outcomes than SP in non-COVID-19 patients and COVID-19 patients without SP. [ABSTRACT FROM AUTHOR]