Objectives: Long-term use of high-dose glucocorticoids can lead to severe immunosuppression and increased risk of treatment-resistant pneumonia and mortality. We investigated the aetiology and prognostic risk factors of mortality in hospitalised patients who developed pneumonia while receiving glucocorticoid therapy alone or glucocorticoid and other immunosuppressant therapies.

Design: Retrospective cohort study

Setting: Six secondary and tertiary academic hospitals in China

Participants: Patients receiving glucocorticoids who were hospitalised with pneumonia between 1^st January 2013 and 31^st December 2019.

Main Outcomes: We analysed the prevalence of comorbidities, microbiology, antibiotic susceptibility patterns, 30-day and 90-day mortality rates, and prognostic risk factors.

Results: A total of 716 patients were included, with pneumonia pathogens identified in 69.8% of patients. Significant morbidities occurred, including respiratory failure (50.8%), intensive care unit (ICU) transfer (40.8%), and mechanical ventilation (36%), with a 90-day mortality rate of 26.0%. Diagnosis of pneumonia occurred within 6 months of glucocorticoid initiation for 69.7% of patients with Cytomegalovirus (CMV) pneumonia and 79.0% of patients with Pneumocystis jirovecii pneumonia (PCP). Pathogens, including Pneumocystis, CMV, and multidrug-resistant bacteria, were identified more frequently in patients with persistent lymphocytopenia and high-dose glucocorticoid treatment (≥ 30 mg/day of prednisolone or equivalent within 30 days before admission). The 90-day mortality rate was significantly lower for non-CMV viral pneumonias than for PCP (P < 0.05), with a similar mortality rate as CMV pneumonias (24.2% vs 38.1% vs 27.4%, respectively).Cox regression analysis indicated several independent negative predictors for mortality in this patient population, including septic shock, respiratory failure, persistent lymphocytopenia, interstitial lung disease, and high-dose glucocorticoid use.

Conclusions: Patients who developed pneumonia while receiving glucocorticoid therapy experienced high rates of opportunistic infections, with significant morbidity and mortality. These findings should be carefully considered when determining treatment strategies for this patient population.

We retrospectively recruited patients with pneumonia who were hospitalised between 1^st January 2013 and 31^st December 2017 at six secondary and tertiary academic hospitals in China. We identified patients with connective tissue diseases, nephrotic syndrome or chronic glomerulonephritis, idiopathic interstitial pneumonia, bronchial asthma, chronic obstructive pulmonary disease, or other causes for immunosuppressive therapy. Study patients were then selected based on the following inclusion criteria: (1) oral or intravenous glucocorticoid treatment [7-9] before admission; (2) pneumonia diagnosis on admission or during hospitalisation; and (3) at least 16 years of age. The exclusion criteria were as follows: (1) diagnosis of noninfectious pulmonary diseases, including lung cancer, interstitial lung diseases without infection, pulmonary embolism, or heart failure; (2) inability to provide consent for procedures.

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