A Retrospective Study on Clinical Characteristics and Outcomes of Patients With Pneumonia

Inclusion criteria

• Age ≥ 18 years old;
• Meet the diagnostic criteria for pneumonia (acute onset + new infiltrates on imaging);
• Have a positive result from pathogen testing;
• Time from onset to admission ≤ 72 hours (to ensure being in the acute phase of the disease);
• Sign a written informed consent form.

Inclusion criteria

for the severe group:

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 Tracheal intubation requiring mechanical ventilation

② Need for vasoactive drugs after active 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)

• Thrombocytopenia (PLT < 100×10⁹/L)

• Decreased body temperature (central body temperature < 36 ℃) ⑨ Hypotension requiring fluid resuscitation

Exclusion criteria

• 1) Patients with severely lacking medical records;

• Those whose main manifestations are other non-infectious diseases (such as pulmonary edema, lung cancer, pulmonary embolism, etc.); 3) Those whose main diagnosis is active pulmonary tuberculosis, non-infectious interstitial lung disease, etc.; 4) Patients considered not applicable by the researchers.