Hospital Harm - Acute Kidney Injury

Inpatient hospitalizations: Includes time in the emergency department and observation when the transition between these encounters (if they exist) and the inpatient encounter are within an hour or less of each other.

The numerator harm, AKI (stage 2 or greater), is defined as a substantial increase in serum creatinine value during the encounter, as evidenced by a subsequent increase in value at least 2 times higher than the lowest serum creatinine value, and the increased value is greater than the highest sex-specific normal value for serum creatinine. The following steps are performed to determine if this criterion for AKI is met: 

 - To identify AKI, evaluate if any serum creatinine value obtained between 48 hours after the start of the encounter and either 30 days after the start of the encounter or discharge, whichever is sooner, is at least 1.5 times higher than the lowest value obtained within the prior 7 days. If yes, then:
 - Evaluate if the increased serum creatinine is greater than the highest sex-specific normal value for serum creatinine. If yes, then:
 - To stage AKI, evaluate if any serum creatinine value obtained between 48 hours after the start of the encounter and either 30 days after the start of the encounter or discharge, whichever is sooner, is at least 2 times higher than the lowest prior value (at any prior time) during that encounter. If yes, then:
 - Evaluate if the increased serum creatinine value is greater than the highest sex-specific normal value for serum creatinine. If yes, then a harm (AKI stage 2 or greater) has been identified.

The highest normal serum creatinine value for females is defined as 1.02 mg/dL. 
The highest normal serum creatinine value for males is defined as 1.18 mg/dL.

The eGFR values are calculated using the CKD-EPI Creatinine Equation (2021), recommended by the National Kidney Foundation. This is a sex-specific, race-neutral formula.

The CKD-EPI Creatinine Equation used for females: 142 x [min((Serum Creatinine)/0.7,1)] raised to the power of (-0.241) x max [((Serum Creatinine)/0.7,1) raised to the power of (-1.200)] x [0.9938] raised to the power of Age x 1.012  

The CKD-EPI Creatinine Equation used for males: 142 x [min((Serum Creatinine)/0.9,1)] raised to the power of (-0.302) x max [((Serum Creatinine)/0.9,1) raised to the power of (-1.200)] x [0.9938] raised to the power of Age  

The "index" serum creatinine is defined as the lowest serum creatinine value within the first 24 hours of encounter start. If there are no serum creatinine values within the first 24 hours, then the index is the first serum creatinine value within the first 48 hours of the encounter start. This serum creatinine value is used to identify and exclude patients with AKI at the start of the encounter.

The "index" eGFR is calculated using the "index" serum creatinine, patient sex, and patient age based on the CKD-EPI Creatinine Equation.

"Initiation" of kidney dialysis (CRRT, hemodialysis and peritoneal) during hospitalization is defined as documentation that kidney dialysis (CRRT, hemodialysis or peritoneal) was started during the encounter.

In addition to clinical electronic health record data, this measure uses Present on Admission (POA)
indicators (e.g., POA = U) as found in billing/claims system within the measure criteria.

The POA Indicator is intended to differentiate conditions present at the time of admission from those conditions that develop during the inpatient admission. 
 - A POA Indicator of Y = yes (Diagnosis was present at time of inpatient admission)
 - A POA Indicator of N = no (Diagnosis was not present at time of inpatient admission)
 - A POA Indicator of W = clinically undetermined
 - A POA Indicator of U = documentation insufficient to determine if the condition was present at the time of inpatient admission

Per CMS and the Agency for Healthcare Research and Quality (AHRQ) convention, POA indicators of Y and W are accepted indicators of a diagnosis present on admission. POA indicators of N and U are accepted indicators of a diagnosis that is not present on admission.

Inpatient hospitalizations for patients age 18 and older without a diagnosis of obstetrics, with a length of stay of 48 hours or longer, and who had at least one serum creatinine value after 48 hours from the start of the encounter

This measure focuses on stage 2 or greater acute kidney injury as an outcome in the hospital inpatient setting. Acute kidney injury affects up to 10% of hospitalized patients (Wilson et al., 2015; Chertow 2005), comparable to the rates of severe sepsis (Hoste, Schurgers, 2008) and acute lung injury (Wilson et al., 2015; Goldstein et al., 2016; McCoy et al., 2010). Less severe acute kidney injury and acute kidney injury requiring dialysis affects approximately 2,000 to 3,000 and 200 to 300 per million population per year, respectively. Up to two thirds of intensive care patients will develop acute kidney injury. Acute kidney injury may result in the need for dialysis, and is associated with an increased risk of mortality (Wilson et al., 2013).

While not all instances of acute kidney injury are avoidable and may be due to natural progression of underlying illness or a complication of a necessary treatment such as chemotherapy, a proportion of acute kidney injury cases are preventable and treatable. The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines suggest careful management of hemodynamic status, fluids, and vasoactive medications for the prevention of acute kidney injury (Wilson et al, 2015). Several studies identified through systematic literature searches developed or evaluated the effectiveness of acute kidney injury electronic alert systems (Selby et al., 2012; Ahmed et al., 2015; Porter et al., 2014; Wilson et al., 2014; Kirkendall et al., 2014; Cho et al., 2012). These studies used data elements for defining acute kidney injury that were already present and populated in the EHR. For acute kidney injury diagnosis, all except two were limited to using serum creatinine levels, suggesting that this is the most reliable and consistently available electronic data element for defining acute kidney injury.

Sex and Age

First vital signs since the encounter start:
 - Temperature
 - Heart Rate
 - Respiratory Rate
 - Systolic Blood Pressure 

The estimated glomerular filtration rate (eGFR) calculated using the index serum creatinine, patient sex, and age-based formula. 

Patient sex collected for risk adjustment and to calculate the eGFR is determined by the AdministrativeGender codes 'F' (female) and 'M' (male). These codes make up the "ONC Administrative Sex" value set and are also used to derive the supplemental data element of patient sex for the measure. 

All encounter diagnoses along with their present on admission (POA) indicators are being collected for the development of baseline risk adjustment model. Targeted diagnoses at the time of development include: 
 - Cancer (leukemia, lymphoma, or metastatic cancer)
 - Diabetes
 - Heart failure
 - Hypertension
 - Obesity

Encounter length of stay

Please see the Hospital Harm - Acute Kidney Injury Risk Adjustment Methodology Report on the eCQM-specific page on the eCQI Resource Center website: https://ecqi.healthit.gov/

Serum creatinine is an accepted proxy for acute kidney disease (KDIGO, 2012). It is cited by many guidelines for defining and monitoring acute kidney injury (Lopes, J., 2013; KDIGO, 2012).

The KDIGO offers clinical practice guidelines for preventing and managing acute kidney injury:

FLUIDS
3.1.1: In the absence of hemorrhagic shock, we suggest using isotonic crystalloids rather than colloids (albumin or starches) as initial management for expansion of intravascular volume in patients at risk for acute kidney injury or with acute kidney injury.

VASOPRESSORS
3.1.2: We recommend the use of vasopressors in conjunction with fluids in patients with vasomotor shock with, or at risk for, acute kidney injury. 

PROTOCOLIZED HEMODYNAMIC MANAGEMENT
3.1.3: We suggest using protocol-based management of hemodynamic and oxygenation parameters to prevent development or worsening of acute kidney injury in high-risk patients in the perioperative setting (2C) or in patients with septic shock.

In April 2019, KDIGO held a follow-up conference entitled Acute Kidney Injury with the following goals: determine best practices and areas of uncertainty in treating AKI; review key relevant literature published since the 2012 KDIGO AKI guideline; address ongoing controversial issues; identify new topics or issues to be revisited for the next iteration of the KDIGO AKI guideline; and outline research needed to improve AKI management. Their discussion identified emerging evidence related to the choice of crystalloid fluids and prevention of drug-related nephrotoxicity, which will be systematically reviewed in a forthcoming KDIGO update.