Last month's column opened a discussion of several complex conditions that complicate the care of oncology patients. Diagnostic documentation needs to properly reflect, in the correct code assignments, the severity of illness of these patients, as well as associated risks, complexity of care, and use of resources.
In this month's column we will investigate the clinical, coding and documentation nuances of 2 common and serious conditions associated with malignancy and cancer treatment: pancytopenia and the sepsis/systemic inflammatory response syndrome (SIRS).
Pancytopenia is a very important, serious comorbid condition commonly occurring among oncology patients, but it is often not specifically documented as such in the medical record. It is defined as suppression of all 3 bone marrow cell-lines resulting in simultaneous neutropenia, thrombocytopenia and anemia. The difficulty with correct identification and diagnosis of pancytopenia lies in the definitions and clinical criteria for these 3 terms.
The medical literature defines neutropenia as an absolute neutrophil count (ANC) less than 1,500 cells per mm3. ANC is often routinely reported and is derived by multiplying the total white blood cell count (WBC) by the percent of neutrophilic cells in the differential count. An ANC less than normal but above 1,500 is not “neutropenia.”
Neutropenia is categorized as:
- mild: 1,000 to 1,500 cells per mm3
- moderate: 500 to 1,000 cells per mm3
- severe: less than 500 cells per mm3
The definition of thrombocytopenia is less clear. The usual lower limit of normal for platelets is 150,000 per mm3 but the finding is not considered clinically significant unless it is less than 100,000 per mm3. The National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE) indicates it should be less than 75,000 per mm3 with categories of:
- mild: 50,000 to 75,000 per mm3
- moderate: 25,000 to 50,000 per mm3
- severe: less than 25,000 per mm3
For anemia, from a clinical perspective, any result below the lower limit of normal for hemoglobin (Hbg)/hematocrit (Hct) is significant. However, the CTCAE only addresses hemoglobin less than 10 g per dL without further specification. The World Health Organization's definition of anemia is more specific and consistent with clinical practice based on hemoglobin levels:
- men: Hbg <13.0 g per dL
- women: Hgb <12.0 g per dL
- pregnant women: Hgb <11.0 g per dL
As a rule of thumb, assuming stable plasma volume, 1 g per dL of Hgb is typically equivalent to 3% Hct, so Hgb of 12.0 g per dL = Hct of 36%.
Identifying the underlying cause of pancytopenia is crucial for correct severity classification. Pancytopenia of any cause is significant, but the condition is considered more severe when due to chemotherapy or other drugs, making it imperative to document this distinction. Pancytopenia is not separately classified when due to aplastic anemia or myelodysplastic or myeloproliferative disorders.
Sepsis is now defined by authoritative, professional consensus standards as SIRS due to suspected or confirmed infection. Non-infectious SIRS can be caused by many conditions including, but not limited to, malignancy, tumor lysis syndrome, extensive or prolonged surgery, pancreatitis and severe burns. Non-infectious SIRS often goes undocumented even when multiple clinical indicators are present.
SIRS or sepsis is recognized when “some” (2 or more) clinical indicators are present (see sidebar at right). The clinician must decide how many indicators are enough in any particular case to warrant the diagnosis based on the clinical circumstances. If a particular indicator, in the clinician's judgment, can be easily explained by another co-existing condition, it should be excluded from consideration in the diagnosis of sepsis/SIRS.
A common clinical scenario is a patient admitted with fever and other signs of sepsis/SIRS without an obvious source of infection. Cultures are obtained; multiple, broad-spectrum antibiotics are administered intravenously; and a search for an infectious source is diligently pursued. After several days, the fever and other signs of sepsis resolve, cultures are negative and no source is identified. What should the final diagnosis be? Is it occult sepsis or was it non-infectious SIRS, due to malignancy or some other cause?
The diagnosis should be established by the management provided based on the physician's judgment of the clinical circumstances. If a full course of antibiotics is continued, the conclusion must be that sepsis of unknown cause was considered likely. Discontinuation of antibiotics following negative cultures indicates that bacterial infection was apparently ruled out. In this case, even though some uncertainty may exist, documentation of the probable, or most likely, cause of SIRS (which could be malignancy) is necessary.
Physicians should be aware that it is a legitimate practice, endorsed by the official coding guidelines, to qualify any uncertain or unconfirmed diagnosis, if clinically reasonable, as “probable,” “possible,” “suspected,” “most likely,” “consistent with,” “compatible with,” “indicative of,” “suggestive of,” “comparable with,” or “appears to be.” When such qualifying terminology is used, it ought to be included in the discharge diagnoses to demonstrate that circumstances did not change prior to discharge.
Diagnosing “fever of unknown origin” or “neutropenic fever” will not reflect the severity of illness or seriousness of the patient's condition since these terms are classified only as the minor symptom of “fever.” Probable sepsis or non-infectious SIRS is preferred for documentation if criteria are met, or at least “possible culture-negative bacteremia” if this is clinically reasonable and a full course of antibiotics has been prescribed.
In summary, identify and document sepsis or non-infectious SIRS together with the underlying cause when clinical criteria are met. Remember that terms of uncertainty like “probable,” “likely,” and “suspected” can be used when they are consistent with clinical findings and management. Pancytopenia (and its cause) is always a significant diagnosis that affects severity of illness classification. It is considered most severe when due to chemotherapy or other drugs.