Table 2.

Algorithm components and incidence rates

¹⁾Worsening oxygenation: defined as at least 2 days of stable or improving oxygenation followed by at least 2 days of (1) decrease in daily minimum oxygen saturation from at least 95% in a patient on ambient air to less than 95%on ambient air, (2) initiation of supplemental oxygen, or (3) escalation of supplemental oxygen. All additional criteria were required to be present on the first or second day of worsening oxygenation

²⁾Chest imaging obtained

³⁾Three days of new antibiotics (less than 3 days of new antibiotics was allowed if the patient died on the first or second day of antibiotics)

⁴⁾Non-intubated patients

⁵⁾Respiratory culture obtained

⁶⁾ICD-10-Australian Modification

⁷⁾Chest radiology including text analysis (a natural language processing searching imaging reports for opacity descriptors consistent with new pneumonia that persisted for > 24 h)

⁸⁾Discharge diagnosis of pneumonia occurring > 48 h after admission

⁹⁾Respiratory and/or blood culture specimen positive for at least one gram-negative organism obtained at hospital day 3 or later for HAP

¹⁰⁾Antibiotic treatment on day of respiratory culture and for a subsequent 3 days or more, or until death or discharge

¹¹⁾ICD-9 pneumonia as a secondary (not primary) diagnosis

¹²⁾Radiological procedures with reports not containing key phrases ruling out pneumonia, and not performed within 48h after admission (unless re-admission

¹³⁾Permanent absence of respiratory device during 48h before radiology

¹⁴⁾ICD-10 U 69.00 proxy code for hospital-acquired pneumonia

¹⁵⁾Positive blood culture from microbiology report

¹⁶⁾General clinical notes or discharge summaries were parsed and mapped to SNOMED-CT concepts (“Lung consolidation” or “pneumonitis”) using a Natural Language Processing (NLP) program

¹⁷⁾Positive blood culture from microbiology report (NLP)

¹⁸⁾(1) antibiotic prescription (ATC: J01) and (2) antibiotic prescription 48 h after ICU admission or time antibiotic prescription changed ≥ 48 h after ICU admission

¹⁹⁾Primary or associated diagnosis of ICU stay coded by anatomical site (ICD 10) as follows: Pneumonia J10-, J11-, J12-, J13-, J14-, J15-, J16-, J17-, J18

²⁰⁾Chest radiology reports including text analysis with an existing NLP system (MedLEE) and chest radiology not performed within 48h after admission