Table 1 Tested severity criteria with the scoring system or severe sepsis definition from each

Systemic inflammatory response syndrome (SIRS) [5]

Two or more of (means SIRS): heart rate ≥90 beats/minute, respiratory rate ≥20 breaths/minute, temperature <36 or ≥38°C, white blood cell count <4 or ≥12 cells/mm³

Standardised early warning system (SEWS) score [12]

Sum of scores allocated for each clinical observation:* respiratory rate, oxygen saturation, temperature, SBP, heart rate, stimulus required to invoke a response

CURB65 pneumonia severity score [16]

One point for each of: new confusion, urea >7 mmol/l, respiratory rate ≥30 breaths/min, SBP <90 mmHg or DBP ≤60 mmHg, age ≥65 years

Institute for Healthcare Improvement website [8]

One or more of (means severe sepsis): SBP <90 mmHg or decreased by >40 mmHg, MAP <70 mmHg, lactate >2 mmol/l, SpO₂ ≤90%, urine output <30 ml/hr, creatinine >177 mmol/l, INR >1.5, APTT >60secs, platelets <100/mm³, bilirubin >35 mmol/l

Surviving Sepsis Campaign guidelines 2008 [7]

One or more of (means severe sepsis): SBP <90 mmHg or decreased by >40 mmHg, MAP <70 mmHg, lactate >4 mmol/l, oliguria, altered mental status

Survive Sepsis™ website [13]

One or more of (means severe sepsis): SBP <90 mmHg, MAP <65 mmHg, lactate >2 mmol/l, SpO2 ≤90%, urine output <30 ml/hr, creatinine >177 mmol/l, INR >1.5, APTT >60secs, platelets <100/mm³, bilirubin >34 mmol/l