Table 2 ESM: Assessment of internal validity of the included articles

Important parameters / Number of valid studies
Sample of patients / (= Hospitalised burn patients)
- Inclusion criteria defined / N= 57 'burn patients'; Inclusion: Minimal TBSA (N= 30); Exclusion: Chronic/previous renal failure (n= 10), death within 48h after admission or do not resuscitate orders (N= 9), late hospital admission (N= 3)
- Sample selection explained / N= 57 (N= 6 only AKI patients mentioned)
- Adequate description of diagnostic criteria (= burn injury) / N= 57
- Clinical and demographic characteristics fully described / Age: N= 47, TBSA: N= 44, Inhalation injury: N= 18, Gender: N= 33
- Representative / N= 57
- Assembled at common point of disease / N= 57 (=admission in burn unit)
- Complete (all eligible patients included) / N= 50 (N= 7 only included AKI patients)
Follow up of patients
- Sufficiently long (= until hospital discharge) / N= 57
- Follow-up after discharge? / N= 7
Outcome
- Objective / n.a.
- Unbiased / n.a.
- Fully defined / n.a.
- Appropriate / N= 57
- Known for all or high proportion of patients / N= 50
Prognostic Variable / (= Acute Kidney Injury)
- Fully defined (= which variables are used for diagnosis AKI?) / N= 50
- Includes details of measurement methods if relevant / n.a.
- Precisely measured (= which exact values are used?) / N= 44
- Available for all or high proportion of patients / N= 57
Analysis / (= Mortality AKI vs. no AKI)
- Continous predictor variable analysed appropriately / n.a.
- Statistical adjustment for all important prognostic factors (=Age, TBSA, inhalation injury, Etiology, …) / N= 0
Treatment subsequent to inclusion in cohort / (= RRT reported?)
- Fully described (= number of AKI-RRT patients is provided) / N= 29
- Treatment standardised or randomised
(= indication of RRT described) / N= 11

Table legend

AKI, Acute Kidney Injury; (AKI-) RRT, (Acute Kidney Injury requiring) Renal Replacement Therapy; n.a., not applicable; N, number of studies