A Prospective Observational Cohort Study Protocol for Disease Severity Stratification and Prognosis Assessment in Patients With Pneumonia

A Prospective Observational Cohort Study Protocol for Disease Severity Stratification and Prognosis Assessment in Patients With Pneumonia

This is a prospective, multicenter observational cohort study involving approximately 2,700 patients, designed to delineate the natural history of pneumonia by tracking the complete clinical course and dynamic multi-omics evolution from the acute phase to recovery; the study aims to quantify severe conversion rates and mortality by comparing baseline characteristics, pathogen distribution, and immune response trajectories between severe and non-severe groups, ultimately revealing the underlying molecular mechanisms of disease progression and optimizing clinical risk stratification strategies.

1. Inclusion and Exclusion Criteria for Pneumonia Patients 1.1 Inclusion Criteria 1) Age ≥ 18 years old; 2) Meeting the diagnostic criteria for pneumonia (acute onset + new infiltrates on imaging); 3) Time from onset to admission ≤ 72 hours; 4) Signed written informed consent. 1.1.1 Inclusion Criteria for Severe Pneumonia Patients A diagnosis of "severe pneumonia" can be made if one of the main criteria or ≥ 3 of the secondary criteria are met.

   Main Criteria:

   ① Requires mechanical ventilation with tracheal intubation

   ② Requires vasopressor drugs after aggressive fluid resuscitation for septic shock

   Secondary Criteria:

   • Respiratory rate ≥ 30 breaths/min

     • PaO₂/FiO₂ ≤ 250 mm Hg

       • Multiple lobe infiltrates

         • Confusion and/or disorientation

           ⑤ Blood urea nitrogen ≥ 20 mg/dL

           ⑥ Leukopenia (WBC < 4×10⁹/L)

           ⑦ Thrombocytopenia (PLT < 100×10⁹/L)

           ⑧ Decreased body temperature (central body temperature < 36 ℃)

           ⑨ Hypotension requiring fluid resuscitation 1.2 Exclusion Criteria

           1. End-stage diseases (such as expected survival < 48 hours);
           2. Long-term immunosuppressive therapy (prednisone > 20mg/d for more than 3 weeks, or neutropenia after chemotherapy);
           3. Pregnant or lactating women. 2. Inclusion and Exclusion Criteria for Patients with Suspected Infection but Negative Pathogen Testing 2.1 Inclusion Criteria
           1. Age ≥ 18 years old;
           2. Having infection-related symptoms or signs (such as fever, cough, sputum production, elevated white blood cells, etc.), clinically suspected of pneumonia;
           3. All pathogen tests are negative within 3 days after admission;
           4. Time from onset to admission ≤ 72 hours;
           5. Signed written informed consent. 2.2 Exclusion Criteria
           1. End-stage diseases (such as expected survival < 48 hours);
           2. Long-term immunosuppressive therapy;
           3. Pregnant or lactating women;