Features of post-obstructive pneumonia in advanced lung cancer patients, a large retrospective cohort.

Background: Post-obstructive pneumonia refers to an infection of the lung parenchyma distal to a bronchial obstruction. Previous experience-based studies reported a high prevalence of this infection among patients with a medical history of advanced lung neoplasia, up to 40-55%.

Objectives: The current study was designed to investigate the features of post-obstructive pneumonia in lung cancer, including its predictors and the discriminants for 30-day mortality.

Method: Data from medical records at the tertiary University centre, UZ Brussel, were collected retrospectively between January 2016 and January 2021. Patients affected by lung cancer stages III and IV were included. A multidisciplinary team, composed of a pulmonologist, an infectious disease specialist and a chest radiologist, identified patients affected by post-obstructive pneumonia.

Results: A total of 408 patients were included, of which 46 (11%) were diagnosed with post-obstructive pneumonia. Multivariable logistic regression for predictors of disease onset found significant differences for squamous cell carcinoma (OR:2.46 -value: .014) and hilar location of the tumour (OR:2.72 -value: .021). However, no significant differences were identified with regards to age or comorbidities. Furthermore, 30-day mortality among post-obstructive pneumonia patients was 30%. Multivariable logistic regression for prediction of 30-day mortality found significant differences in CURB-65 score (OR:73.20 -value: .001) and smoking status (OR:0.009 -value: .015).

Conclusions: Within this cohort, the prevalence of post-obstructive pneumonia in advanced lung cancer patients was lower than previously reported. Squamous cell carcinoma and a hilar tumour location were two variables associated with disease development, independent of age and comorbidities. Furthermore, a higher CURB-65 score at post-obstructive pneumonia diagnosis was correlated with mortality.