[Chinese expert consensus on the diagnosis and treatment of severe pneumonia in immunocompromised hosts].

The population of immunocompromised hosts has steadily increased in recent years. Clinical evidence indicates that these individuals are at a significantly higher risk of developing severe pneumonia following infection, with the mortality rates markedly higher than those observed in immunocompetent individuals. However, there is currently a lack of specific national or international guidelines or expert consensus addressing the management of severe pneumonia in this population. To address this unmet need, the Chinese Thoracic Society (CTS) of the Chinese Medical Association and the Oncology Respiratory Disease Committee of China Anti-Cancer Association (CACA) convened a multidisciplinary panel of experts from respiratory and critical care medicine, infectious diseases, and related fields in China to develop the present consensus.This consensus addresses 14 key clinical questions, covering topics such as the definition and classification of immunocompromised hosts, and the diagnosis and treatment of severe pneumonia in this high-risk group. The panel systematically reviewed evidence and formulated recommendations using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework. The resulting consensus aims to standardize clinical practice, support evidence-based decision-making, and eventually improve outcomes for immunocompromised patients with severe pneumonia in China.Question 1: Definition and classification of immunocompromised Hosts.Recommendation 1: An immunocompromised host is defined as a patient with a significantly weakened or absent immune response to pathogens owing to various intrinsic or extrinsic factors. The immunocompromised status is categorized as either primary or secondary. This assessment should integrate the patient's underlying conditions with available immunological parameters.Question 2: What are the diagnostic criteria for severe pneumonia in immunocompromised hosts, and which indicators are recommended for severity assessment?Recommendation 2: Severe pneumonia in immunocompromised hosts is diagnosed based on the criteria outlined by the 2016 Chinese guidelines for community-acquired pneumonia (CAP). Disease severity and immune status should be assessed at initial diagnosis to evaluate risk and guide treatment decisions. Hospitalization thresholds may be appropriately reduced in this population (1C).Question 3: What are the diagnostic and therapeutic workflows for severe pneumonia in immunocompromised hosts, and how should infectious pneumonia be distinguished from non-infectious pulmonary infiltrates?Recommendation 3: A multidimensional approach is recommended for differentiating severe pneumonia from non-infectious pulmonary infiltrates in immunocompromised hosts. Clinical, radiological, and microbiological data should be integrated. When necessary, histopathological biopsy and/or multidisciplinary team (MDT) consultation should be performed. The detailed diagnostic and therapeutic workflow are illustrated in Figure 1 (1A).Question 4: What are the major pathogens causing pneumonia in immunocompromised hosts, and how does pathogen distribution differ across immunosuppressive states?Recommendation 4: The core pathogens causing pneumonia in immunocompromised hosts are usually similar to those in immunocompetent hosts. However, pathogen distribution is more diverse, with immunocompromised hosts showing a higher prevalence of opportunistic pathogens and mixed infections (Table 5 and Figure 1A).Question 5: What are the recommended timings and methods for obtaining clinical specimens from immunocompromised hosts?Recommendation 5: High-quality clinical specimens are necessary for etiological diagnosis. Once infection is suspected, early sampling for microbiological testing is recommended. The sampling approach should be individualized based on the patient's condition and the clinical team's experience (1B).Question 6: How to choose diagnostic methods for pathogen identification in immunocompromised hosts with pneumonia?Recommendation 6: For immunocompromised hosts with severe pneumonia, comprehensive microbiological testing should be performed before or concurrently with empirical therapy to identify pathogens as early as possible and guide treatment strategies (1A).Question 7: What are the principles of anti-infective therapy for severe pneumonia in immunocompromised hosts?Recommendation 71. Initial empirical therapy should target drug-resistant Gram-negative and Gram-positive bacteria, with expansion of coverage when risk factors are present (1A).2. For ventilator-associated pneumonia (VAP), combination regimens that include β-lactams are recommended (1A).3. Echinocandins are preferred for treating invasive pulmonary candidiasis, and a switch to azoles may be considered when appropriate (1A).4. Empirical coverage for cytomegalovirus pneumonia is recommended for patients developing bilateral interstitial pneumonia shortly after lung transplantation or hematopoietic stem cell transplantation (1A).Question 8: What factors should be considered when selecting empirical anti-infective therapy for severe pneumonia in immunocompromised hosts?Recommendation 8: Empirical therapy should be selected based on the type and degree of immunodeficiency, healthcare exposure, risk of antimicrobial resistance, severity of infection, microbiological findings, treatment response, and preventive strategies (1A).Question 9: What are the recommended treatment durations for different pathogens in severe pneumonia among immunocompromised hosts?Recommendation 9: Treatment duration primarily depends on clinical presentation, radiographic changes, severity of infection, pathogen resistance profile, and the immune status of patients (1A).Question 10: Which respiratory support strategies should be prioritized for immunocompromised hosts with severe pneumonia complicated by respiratory failure?Recommendation 10: Noninvasive respiratory support is preferred for immunocompromised hosts with severe pneumonia and respiratory failure who do not require immediate intubation. High-flow nasal oxygen (HFNO) or noninvasive positive-pressure ventilation (NPPV) may be selected (1A).Question 11: When is tracheal intubation most appropriate for immunocompromised hosts with severe pneumonia?Recommendation 11: The timing of tracheal intubation in immunocompromised hosts is usually similar to that in immunocompetent hosts (1A).Question 12: When should extracorporeal membrane oxygenation (ECMO) be initiated in immunocompromised hosts with severe pneumonia and respiratory failure?Recommendation 12: The timing of ECMO initiation should be determined based on the same criteria as those used for immunocompetent hosts (1A).Question 13: For immunocompromised patients with severe pneumonia and respiratory failure, is early extubation followed by NPPV or HFNO a viable option?Recommendation 13: Early extubation followed by NPPV or HFNO can be actively considered for immunocompromised patients with severe pneumonia complicated by respiratory failure. In the absence of contraindications to NPPV, NPPV may be attempted as the initial post-extubation strategy (1A).Question 14: What recommendations are there for immunomodulatory therapy in immunocompromised hosts with severe pneumonia?Recommendation 14: Immunomodulation is an important component of therapy in immunocompromised hosts with severe pneumonia. Immune status should be assessed to guide individualized immunoregulatory strategies (1B).