Intensive Monitoring of Renal Function

Intensive monitoring of renal function provides an early opportunity to modify or attenuate certain risk factors (e.g., nephrotoxin exposure) for AKI. Intensive monitoring of urine output (UO) provides a real-time continuous assessment of renal function in the ICU. However, the association between intensive monitoring and less-intensive monitoring of urine output, with or without close monitoring of serum creatinine (sCr), on susceptibility to AKI and outcomes from AKI are unknown. Our preliminary data indicates that intensive monitoring of UO is associated with lower hospital mortality as compared to less-intensive monitoring for patients that develop AKI. If intensive monitoring of renal function is associated with lower risk of AKI and improved outcomes from AKI, then such monitoring techniques could be widely used in hospitalized patients including non-intensive care settings to either prevent AKI or progression of AKI.

Therefore, this observational retrospective cohort study aims to compare the outcomes of patients undergoing intensive monitoring of renal function (UO and/or sCr) with those of patients undergoing less intensive monitoring. Outcomes will include mortality within 30 days of ICU admission among critically ill patients with and without AKI. Development of severe AKI within 7 days of ICU admission and fluid overload on any ICU day in patients who develop severe AKI (KDIGO stage 3) will also be assessed.

This study will utilize a large, heterogeneous cohort (n=~54,800) of critically ill patients admitted to the ICU over 8 year period at the University of Pittsburgh Medical Center. The study population will consist of patients who receive intensive monitoring of UO (defined as measured at least every 2 hours within the first 48 hours of ICU admission) and strict creatinine measurement (defined as at least daily). Patients who fail to meet criteria for intensive monitoring will be controls (less-intensive monitoring group). AKI will be diagnosed according to the KDIGO stage 1-3 criteria over a 7-day period. Mortality at 30-days from ICU admission will be ascertained using the social security death master file. In order to account for indication bias, a propensity score for intensive monitoring will be built using various risk factors. Risk and severity of illness-adjusted estimates will be generated for susceptibility to AKI and mortality from AKI between intensive and less-intensive monitoring groups.

Inclusion criteria

• Critically ill patient admitted to ICU
• Required vasopressor support or mechanical ventilation in the 24 hours from ICU admission

Exclusion criteria

• History of chronic dialysis and/or renal transplant
• Baseline serum creatinine >= 4 mg/dl
• Insufficient data to determine AKI stage in the 7 days from ICU admission
• Died within 48 hours from ICU admission
• ICU duration <2880 minutes