Part 5: Reasons for AKI Denials and Prevention | AKI Series

Part 5 of this series is the final part. In this tip, we will look at some of the common reasons given for acute kidney injury (AKI) denials and what coders can do to help prevent these.

Why are so many AKI records being denied?

It’s hard to give one answer for why so many AKI records are being denied lately, but most appear to be due to the multiple sets of criteria available for use in determining if a patient has AKI, as well as physician documentation. As stated in Part 3 of this series, there are three main criteria/classifications used to diagnose AKI. Below are the common classifications used to help explain what some of the denial examples are referring to:

  • RIFLE Classification—Risk, Injury, Failure, Loss and End-stage kidney disease. Established and published in 2004. Created with primary goal to develop a consensus and have evidence-based guidelines for the treatment and prevention of AKI. (See criteria reference below)
  • AKIN Classification—Acute Kidney Injury Network. Established and published in 2007. This is a  modified version of the RIFLE criteria. This was established in order to increase the sensitivity and specificity of the diagnosis of AKI. AKIN advised that acute renal failure be changed to acute kidney injury to represent the full spectrum of renal injury (mild to severe). (See criteria reference below)
  • KDIGO Classification—Kidney Disease Improving Global Outcomes. Released in 2012 for use and is a build off of the RIFLE and AKIN criteria already being used. This criteria reserved the baseline creatinine that was established in RIFLE and a small increase in creatinine from AKIN. This is thought to give KDIGO greater sensitivity than RIFLE or AKIN. (See criteria reference below)

When looking at these different classifications for AKI, and the criteria that is being used, it’s evident that the majority of the issues for denials depend on which classification is being used by the physician, and which by the patient’s insurance carrier. There are no specific classification or criteria mandated for use in diagnosing AKI, so oftentimes the one used by the physician and the insurance provider don’t match.

This makes it difficult for coders as well as CDI, physicians and facilities. Coders, CDI and physicians should be aware of any specific coding and documentation guidelines that have been agreed upon with an insurance company or payer. Some contracts will specify which AKI classification they will be using to validate a reported diagnosis of AKI. If there is a contract stating which classification they will be using to validate the diagnosis of AKI, then that is the one that must be met for reporting purposes. It is evident by the reason for denials (listed below) that this is not being followed. Coding and or Health Information Management (HIM) should be involved and aware of anything in a contract that pertains to coding and documentation requirements of health care records. The language used in contracts for some payers on reporting the diagnosis of AKI is relevant to being able to appeal a denial.

Are AKI denials the coder’s fault? Not usually! The majority of these denials are clinical denials. A clinical denial audit is when the payer is questioning whether or not the physician’s diagnosis of AKI is clinically supported. The rest are usually due to conflicting documentation amongst multiple physicians documenting the diagnosis of AKI (such as injury, insufficiency, specific cause or possible condition not documented at discharge) and no query sent for clarification. Coders should be querying whenever conflicting documentation of a diagnosis is in the record.

Examples of denial reasons:

  • “The diagnosis of ATN was not found in the medical record”
  • “The query was noncompliant”
  • “There were no documented signs or symptoms that would have been consistent with the diagnosis of AKI. Only a slight increase in creatinine documented. Without additional signs and symptoms, or other laboratory proof or treatment the diagnosis is not supported”
  • “Significant resources were not used in the management of the diagnosis”
  • “A query was warranted in the situation but not found”
  • “Lack of clinical indicators documented in the medical record”
  • “The treatment provided did not reflect resources needed for the diagnosis of AKI”
  • “Diagnosis is acknowledged to be in the medical record from the physician but don’t think this is a valid diagnosis”
  • “Documentation does not support the diagnosis of AKI as defined by the RIFLE criteria”
  • “Documentation does not support the diagnosis of AKI as defined by the AKIN criteria”
  • “Documentation does not support the diagnosis of AKI as defined by the KDIGO criteria”
  • “The clinical indicators within the medical record can be explained by the patient’s dehydration and do not justify a diagnosis of acute kidney injury”

Can the coders prevent acute kidney injury (AKI) denials for clinical validity?

Absolutely! As you can see, in the examples above the majority of the denials for the diagnosis of AKI are due to lack of clear documentation of the diagnosis, or the lack of clinical indicators to support the diagnosis of AKI within the medical record. Remember, even if coded based on the physician documentation, if there are no clinical indicators present to support the diagnosis, there is a high chance of denial. When this occurs, it impacts the entire facility. Denials are expensive. Payment must be returned and/or not received. The facility must spend time to review the records that are denied and all this just adds up.

What can coders do to help prevent costly denials on AKI?

  • Educate providers and CDI on what is needed in the documentation such as a good history and physical if AKI is present at time of admission and/or in the hospital course to capture the severity of illness, and also any signs and symptoms related to the diagnosis of AKI. The hospital course should include a detailed summary of the finding, the workup done as well as treatment needed to improve the acute injury.
  • Any clinical signs and symptoms or other indicators that are related to AKI should be linked to the diagnosis in the medical record. If they are not linked, it is easy for the payer to relate them to another condition such as dehydration.
  • Documentation should be consistent and complete…if not, a query is necessary for clarification.
  • Collaboration between coders, CDI and physicians to ensure that the documentation clearly describes the condition of AKI.
  • Facilities should have an escalation policy for CDI and/or coders to send records that lack clinical support of AKI prior to finalizing the record.
  • Coders, CDI and physicians should be aware of the different AKI classifications/criteria used.
  • If there are contracts with certain payers on what classification/criteria will be used for validation of AKI, the coders, CDI and physicians should be aware of this. If they are not aware then there may surely be lacking documentation in the record.
  • QUERY at the time of coding prior to billing/finalization.
  • NEVER depend on the denial letter to list all the clinical indicators in the record. ALWAYS complete a full review of the medical record to be sure that there are no other clinical findings to help support the diagnosis that was reported. Oftentimes, only a superficial or minimal review of the record may lead to a claim denial.
  • Consider having a second level review to determine if there is clinical validity within the record to support the diagnosis of AKI before billing/finalizing.
  • Appeal letters should include ALL of the supporting documentation in the record for AKI and any references that help to support reporting this diagnosis.
  • When writing an appeal letter, be sure and state that you realize that there are differences of opinion on the criteria used for the diagnosis of AKI, but none have been mandated for use.

Remember, even if coded based on the physician documentation, if there are lacking clinical indicators to support the diagnosis, there is a high chance of denials. When this occurs, it impacts the entire facility.



The information contained in this coding advice is valid at the time of posting. Viewers are encouraged to research subsequent official guidance in the areas associated with the topic as they can change rapidly. 

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