A reader recently wrote asking about whether it was acceptable, in coding for a patient with sepsis, to automatically link lactic acidosis to acute organ dysfunction that qualifies for assignment of a severe sepsis code (e.g., R65.20) without further clarification. The medical staff at the reader's hospital had decided to follow Sepsis-2 definitions and criteria rather than Sepsis-3.
Coding guidelines state that any acute organ dysfunction (e.g., acute kidney injury, acute respiratory failure, coagulopathy) specifically documented as due to or associated with sepsis should be assigned a severe sepsis code and that no further clarification of whether the dysfunction represents severe sepsis is required.
Codes for any acute organ dysfunction are then assigned as secondary diagnoses with sepsis as the principal diagnosis. The severe sepsis code is also assigned as a secondary diagnosis. ICD-10-CM gives a nonexclusive list of several examples of acute organ dysfunction that qualify for assignment of a severe sepsis code (Table). But any condition attributed to sepsis by the clinician qualifies as long as it has a reasonable clinical basis. Sepsis-2 provides certain other conditions not specifically listed by ICD-10-CM that are also indicative of severe sepsis, including total bilirubin greater than 2 mg/dL, ileus, platelets less than 100,000/μl, international normalized ratio greater than 1.5, activated partial thromboplastin time greater than 60 seconds, and septic shock.
Elevated lactate levels (hyperlactatemia) may occur in sepsis with and without acidosis. The 2012 Surviving Sepsis Campaign (SSC) update of Sepsis-2 criteria for severe sepsis included hyperlactatemia with lactate levels above 2 mmol/L representing tissue hypoperfusion that is a manifestation of cardiovascular/circulatory system dysfunction.
Clinical research has shown that hyperlactatemia with lactate levels above 4 mmol/L is equivalent to septic shock even in cases that haven't met definitive hypotension criteria. For that reason, the 2012 SSC update added this criterion as an independent indicator of septic shock regardless of the severity of hypotension.
The CMS Hospital Inpatient Quality Reporting (IQR) Program has adopted the National Quality Foundation's (NQF) Severe Sepsis Management Bundle #0500, in which the definition of septic shock includes “sepsis-induced hypoperfusion persisting despite adequate fluid resuscitation or lactate >4 mmol/L.”
The question is sometimes raised whether hyperlactatemia and lactic acidosis can be considered “organ” dysfunction, and if so, what organ? The answer lies within ICD-10-CM itself.
Lactic acidosis is classified by ICD-10-CM as a specific diagnostic condition (coded E87.2) comparable to those conditions shown in the Table. It represents acute dysfunction of the cardiovascular/circulatory organ system. Hyperlactatemia (identified by ICD-10-CM as “excessive lacticemia”) is also assigned to this code.
Therefore, assignment of a severe sepsis code for lactic acidosis or hyperlactatemia specifically linked to sepsis by a clinician without further clarification is completely consistent with ICD-10-CM and the clinical reality. The cardiovascular/circulatory system does not have to be mentioned in this connection.
Despite this support from ICD-10-CM and authoritative clinical evidence, auditors may not agree. The most prudent approach is for clinicians to add documentation of “severe sepsis” when sepsis is clearly associated with hyperlactatemia indicated by lactate levels above 2 mmol/L and “septic shock” when lactate levels are above 4 mmol/L.
Another issue is that Sepsis-2 definitions and criteria (systemic inflammatory response syndrome [SIRS] due to infection) are no longer the authoritative clinical diagnostic standard for sepsis recognized by SSC, having been replaced by Sepsis-3, which was published in February 2016 and adopted by SSC in March 2017. Appeals of auditor denials based on Sepsis-2 criteria are unlikely to be successful, but all such cases should be reviewed for the possibility of using Sepsis-3 diagnostic criteria as the basis for appeal.
In summary, acute organ dysfunction (e.g., acute kidney injury) specifically documented as due to or associated with sepsis may be assigned a severe sepsis code without further clarification. Based on ICD-10-CM instructions, lactic acidosis or hyperlactatemia appear to qualify as a manifestation of acute organ dysfunction following this rule. Adding documentation of “severe sepsis” when sepsis is associated with hyperlactatemia indicated by lactate levels above 2 mmol/L and “septic shock” when lactate levels are above 4 mmol/L makes the case even stronger.