Table 2.

Endpoints and definitions proposed for infection and inflammation theme. ^∗Note any deviation from CDC definition is attributable to paraphrasing for ease of presenting in results table. ^†Note as per the CDC definitions there is a group of operations where a 90 day duration is used for this endpoint, please consult Supplementary Table S4.The exact CDC definition is proposed, and these are given fully in the appendix. ^‡Definition as per the Third International Consensus Definitions for Sepsis and Septic Shock (SEPSIS-3). CDC, US Centers for Disease Control; CRP, C-reactive protein; SOFA, Sequential Organ Failure Assessment; WBC, white blood cell count

Endpoint	Proposed definition
Fever	▪Core body temperature >38.5°C more than 24 h after operation, and two readings in a 12 h period
Respiratory Infectious Complication—CDC definition∗	▪Signs/Symptoms/Laboratory: ONE of [fever >38.0°C, WBC <4×109 or >12×109 L−1, altered mental status in >70 yr old with no other recognised cause] and TWO of [new onset purulent sputum/change in character of sputum/increased respiratory secretions or increased suctioning OR worsening cough/dyspnoea/tachypnoea OR rales or bronchial breath sounds OR worsening gas exchange] ▪Imaging: two or more serial chest imaging results with either [new and persistent OR progressive and persistent] changes of [infiltrate OR consolidation OR cavitation] ▪ OR one of: - Organism seen on Gram stain of lung tissue or pleural fluid, or identification of pathogenic organism from fluid or tissue from affected site (see outcome 3) - Abscess or other evidence of infection on gross anatomical or histopathologic examination - Imaging test evidence of abscess or other infection which if equivocal is supported by clinical correlation, specifically, physician documentation of antimicrobial treatment for lung infection
Neurological Infectious Complication—CDC definition∗	▪ ONE of: - Identification of pathogenic organism from fluid or tissue from affected site (see outcome 3) - Abscess or evidence of intracranial infection on gross or anatomical or histopathologic examination ▪TWO of [headache, dizziness, fever >38°C, localising neurological signs, changing level of consciousness, confusion] and ONE of [organism seen on microscopic examination of brain or abscess tissue obtained by needle aspiration or during invasive procedure or autopsy OR imaging suggestive of infection which is equivocal is supported by clinical correlation OR diagnostic single antibody titre or 4-fold increase in paired sera for organism] ▪TWO of [fever >38°C or headache, meningeal signs, cranial signs] AND ONE OF: [increased WBC elevated protein and low glucose in CSF OR organism on Gram stain of CSF OR organism identified on blood culture, diagnostic antibody titre or 4-fold increase in paired sera for organism] ▪Within 30 days2
Urinary System Infectious Complication—CDC definition1∗	▪ ONE of: - Identification of pathogenic organism from fluid or tissue from affected site (see outcome 3) - Abscess or other evidence of infection on gross anatomical examination, during invasive procedure, or during histopathologic examination - ONE of [Fever >38°C, localised pain or tenderness with no other recognised cause] AND ONE OF [purulent drainage from affected site OR organism identified in blood by culture or non-culture based biological testing OR imaging suggestive of infection which if equivocal is supported by clinical correlation, specifically physician documented treatment for urinary system infection] ▪Within 30 days2
Clostridium difficile Colitis/Infection—CDC definition∗	▪ ONE of: - Positive test for toxin-producing C. difficile on an unformed stool sample - Patient has evidence of pseudomembranous colitis on gross anatomical or histopathologic examination ▪Within 30 days2
Endometritis—CDC definition∗	▪ ONE of: - Identification of pathogenic organism from fluid or tissue from affected site (see outcome 3) - TWO of [fever >38.0°C, uterine or abdominal pain or tenderness with no other recognised cause, purulent drainage from the uterus] ▪Within 30 days2
Identification of Pathogenic Organism from Tissue or Fluid	▪Organisms identified from aseptically obtained fluid or tissue in the organ space by a culture or non-culture based testing method which is performed for the purposes of clinical diagnosis and treatment ▪Within 30 days2
Surgical Site Infection	▪Total of superficial and deep SSIs
Superficial Incisional Surgical Site Infection—CDC definition∗	▪Involves only skin and subcutaneous tissue of the incision AND at least one of [purulent discharge from superficial incision or subcutaneous tissue OR organisms identified from specimen from superficial incision OR superficial incision deliberately opened by surgeon/treating physician with one of pain, tenderness, localised swelling, erythema, or heat OR diagnosis of superficial SSI by surgeon/treating physician] ▪Within 30 days2
Deep Incisional Surgical Site Infection—CDC definition∗	▪Involves deep soft tissues of incision (fascial and muscle layers) AND at least one of [purulent discharge from deep incision OR deep incision that spontaneously dehisces or is deliberately opened or aspirated by treating surgeon/treating physician and has microorganism identified on microbiological testing with either fever >38.0°C or localised pain or tenderness OR an abscess or other evidence of infection involving the deep incision is identified on gross anatomical examination or imaging] ▪Within 30 days†
Organ/Space Surgical Site Infection—CDC definition∗	▪Infection involves a part of the body deeper than the fascial/muscle layers, that is opened or manipulated during the operative procedure AND one of [purulent drainage from drain in organ/space OR organisms identified from aseptically obtained fluid or tissue in the organ space by a culture or non-culture based testing method which is performed for the purposes of clinical diagnosis and treatment OR an abscess or other evidence of infection involving the organ/space that is detected on gross histopathologic examination OR imaging test evidence suggestive of infection] ▪Within 30 days†
Sepsis‡	▪Increase in SOFA score of 2 or more, with evidence of infection ▪Within 30 days†
Septic Shock‡	▪Sepsis (SOFA score or 2 or more with evidence of infection) with shock ▪Vasopressor requirement to maintain a mean arterial pressure of 65 mm Hg or greater and serum lactate level greater than 2 mM (>18 mg dl−1) in the absence of hypovolaemia