Length of stay will be calculated as the total number of full days between admission and discharge from the ICU. A calendar day will be counted toward the total only if the duration of stay on that day is two hours or longer.

Length of stay will be calculated as the total number of full days between admission and discharge from the hospital. A calendar day will be counted toward the total only if the duration of stay on that day is two hours or longer.

Recovery will be defined as improvement in kidney function based on serum creatinine value at hospital discharge compared with baseline serum creatinine.

Baseline serum creatinine will be defined as either of the following (in order of priority) 1) Average of 3 closest outpatient values 7-365 days before index hospitalization; 2) Lowest value in the inpatient setting 7-365 days before index hospitalization; 3) Lowest value in the first 30 days during index hospitalization (not during or within 48h after RRT discontinuation).

Patients who have serum creatinine <0.3 mg/dL higher than baseline at hospital discharge will be considered to have recovered renal function.

Recovery will be defined as improvement in kidney function based of serum creatinine value at follow-up compared with baseline serum creatinine.

Baseline serum creatinine will be defined as either of the following (in order to priority) 1) Average of 3 closest outpatient values 7-365 days before index hospitalization; 2) Lowest value in the inpatient setting 7-365 days before index hospitalization; 3) Lowest value in the first 30 days during index hospitalization (not during or within 48h after RRT discontinuation).

Patients who have serum creatinine <0.3 mg/dl higher than baseline at follow-up will be considered to have recovered renal function.

Patients will be classified as RRT-dependent if they continue to require any form of RRT at discharge. Patients who no longer require RRT will be classified as RRT-independent.

Patients will be classified as RRT-dependent if they continue to require any form of RRT at follow-up assessment. Patients who no longer require RRT will be considered RRT-independent.

These include complications attributable to different types of anticoagulation (systemic unfractionated heparin, systemic low molecular weight heparin, regional citrate anticoagulation, other) used during RRT. Events include hemorrhage, heparin-induced thrombocytopenia (where relevant), citrate excess (where relevant), and citrate deficit (where relevant).

These include infections associated with RRT. Events include catheter-related bloodstream infections, catheter insertion-site infections, and secondary peritonitis.

Procedural or mechanical complications occurring during RRT will be identified from medical records and bedside documentation. These include catheter malfunction (e.g., kinking, disconnection, malposition, migration, catheter tip adherence to vessel wall), circuit interruptions, circuit replacements, RRT downtime (where relevant).