Table 1.
Definitions of diagnostic criteria
| Variable | Definition |
|---|---|
| AKI | Increase in serum creatinine by ≥ 0.3 mg/dL (≥26.5 µmol/L) within 48 h OR increase in SCr to >1.5 times baseline that is known or presumed to have occurred within the prior 7 days OR urine volume <0.5 mL/kg/h for 6 h [13] |
| Pre-existing kidney dysfunction | eGFR <60 mL/min/1.73 m2 [14] |
| Anaemia | Haemoglobin <11 g/dL [15] |
| Sepsis | The presence of confirmed (culture) or presumed identifiable microbes with two or more features of SIRS. Features of SIRS include fever (temperature >38 °C) or hypothermia (temperature <36 °C), tachycardia (pulse rate >90/min), tachypnoea (respiratory rate >20/min) and leucocytosis (WBC >11 × 106/mm3) or leucopenia (WBC <4 × 106/mm3) [16, 17] |
| Hypertension | SBP ≥140 mmHg or diastolic DBP ≥90 mmHg, presence of hypertension previously diagnosed by a physician or use of antihypertensive medications to control BP [18] |
| Diabetes mellitus | Fasting plasma glucose >7 mmol/L, diabetes mellitus diagnosed previously by a physician or use of antidiabetic medications to control blood sugar [19] |
| Intra-operative hypotension | Increase in mean arterial BP > 20% from the baseline, lasting 5–10 min. Intra-op hypotension was defined as absolute SBP <80 mmHg or a drop in the baseline SBP of >20% lasting at least 5–10 min [20, 21] |
| Major surgery | Any surgical procedure that required at least a regional or general anaesthesia, surgery that lasts >120 min in duration or surgery requiring in-hospital care |
| Full recovery of kidney function | SCr return to baseline value or below [22] |
| Partial recovery of kidney function | Change from higher AKI severity stage to a lower one but not below Stage I or a reduction in SCr of > 25% from the highest value attained [22] |
| Prolonged surgery | Surgical interventions lasting >120 min [23] |
| KDIGO staging of AKI | |
| Stage I | Increased SCr 1.5–1.9 times from the baseline OR urine output <0.5 mL/kg/h for 6–12 h |
| Stage II | Increased SCr 2.0–2.9 times from baseline OR urine output <0.5 mL/kg/h for ≥12 h |
| Stage III | Increased absolute SCr to > 4.0 mg/dL (>353.6 mmol/L) OR initiation of RRT OR increased SCr 3.0 times from baseline OR 0.3 mL/kg/h for ≥24 h OR anuria for ≥12 h [13] |
SIRS, systemic inflammatory response syndrome; WBC, white blood cell count.