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Table 2 Definition of outcome measures

From: 0.9% Sodium chloride solution versus Plasma-Lyte 148 versus compound sodium lacTate solution in children admitted to PICU—a randomized controlled trial (SPLYT-P): study protocol for an intravenous fluid therapy trial

Outcome Criterion Definition
Primary
 Hyperchloremia Increase in serum chloride ≥ 5 mmol/L - Difference from baseline level to the highest chloride level measured within 48 h post-randomization
- Baseline level: measured on blood gas at randomization or using the closest lab or blood gas value up to a maximum of 12 h before randomization
- Highest chloride level: obtained in the first 48 h post-randomization
- Patients will be assumed to have no hyperchloremia if chloride has not been measured in the first 48 h post-randomization
Secondary (clinical)
 Organ dysfunction free survival Survival free of organ dysfunction - Organ dysfunction defined by Paediatric Logistic Organ Dysfunction 2 Score – PELOD-2) [19]
- A PELOD-2 score of > 0 indicates organ dysfunction
- Censored at 28 days post-randomization
- Assume PELOD-2 is zero at discharge from PICU in survivors
- PELOD-2 calculated using the worst values of individual components each day until discharge
- If a certain variable (such as creatinine) was not measured on a given day, it is assumed to be normal [19]
 Acute kidney injury (AKI) New-onset AKI - AKI defined as per KDIGO 2012 criteria using serum creatinine values [20]
- Includes AKI within the first 7 days post-randomization if not present on admission. Serum creatinine values measured in the first 7 days post-randomization will be used to assess AKI as per KDIGO 2012 criteria
- Baseline creatinine: closest serum creatinine value prior to randomization, up to 12 h before randomization
- Predicted baseline creatinine: for children <1 year, the reported predicted creatinine values by Boer et al. will be used, whilst for children >1 year, the below formula will be employed [21].
Mean creatinine (micromol/L) = − 2.37330 − 12.91367 * loge (age) + 23.93581 * (age)1/2 [22]
Presence of AKI on admission:
For those with baseline creatinine:
- Baseline creatinine ≥ 1.5 times predicted baseline creatinine for those with baseline creatinine
For those without baseline creatinine:
- Patients will be assumed to have no AKI on admission
New onset AKI:
For those with baseline creatinine:
- New-onset AKI will be according to KIDIGO 2012 criteria using follow-up creatinine values. If no follow-up creatinine available, these patients would be deemed to have no AKI
For those without baseline creatinine:
- Predicted baseline creatinine value will be calculated and assumed to be the baseline value. This value will be compared to the follow-up value (where available) as per KDIGO 2012 criteria. Where no follow-up value is available, these patients would be deemed to have no AKI.
 Length of stay Length of stay - Length of stay in PICU from randomization to discharge
- Length of stay in hospital from randomization to discharge
 Survival PICU free survival - Censored at 28 days from the post-randomization
- Patients will be assumed to be alive once discharged from PICU
- For patients who die within 28 days, are discharged to a hospice or for palliative care, this value will be recorded as zero
Secondary safety outcomes, defined as serum electrolyte/metabolite abnormalities present from randomization to 48 h post-randomization
 Adverse event Hyperkalaemia - Serum potassium > 6.2 mmol/L
Hypokalaemia - Serum potassium < 2.5 mmol/L
Hypercalcaemia - Serum corrected total calcium > 3.1 mmol/L
Hypocalcaemia - Serum corrected total calcium < 1.6 mmol/L
Hypermagnesaemia - Serum magnesium > 1.4 mmol/L
Hyponatraemia - Serum sodium < 125 mmol/L
Hyperlactataemia - Arterial or venous blood gas lactate > 4 mmol/L
Death in hospital - Number of deaths
  1. Legend: PICU paediatric intensive care unit, AKI acute kidney injury, KDIGO Kidney Disease: Improving Global Outcomes, PELOD-2 Paediatric Logistic Organ Dysfunction 2 Score