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Coding in the Long-Term Acute Care Setting

Coding in the Long-Term Acute Care Setting

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Coding in the Long-Term Acute Care Setting

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Understanding the similarities and differences of coding in the LTAC setting is a challenge unlike any you find when coding in the acute care hospital

The patient is a 78-year-old female with a history of coronary artery disease (CAD) and hypertension, who was in relatively good health until found at home exhibiting altered mental status and profound weakness. She was brought to the acute care hospital in a dehydrated state with an elevated temperature. Upon work-up, the patient was found to have a non-displaced fracture of the neck of the femur and was brought to surgery for open reduction, internal fixation of the fracture. During the postoperative hours, the patient suffered a cerebrovascular accident. Her course continued downhill, and she developed atrial fibrillation, a urinary tract infection and deep vein thrombosis. She was evaluated and subsequently transferred to the long-term acute care (LTAC) hospital with the above diagnoses and on the following IV medications: Lasix, Coumadin and Zosyn.

During her stay at the LTAC, she was treated for all the above diagnoses and received comprehensive rehabilitative services. What is her principal diagnosis?


The above scenario is a common one for those of us who code in one of the more than 275 LTACs in the United States. Understanding the similarities and differences of coding in this setting is a challenge unlike any that you find when coding in the acute care hospital. Use and interpretation of the ICD-9-CM coding guidelines pose specific difficulties not routinely found in the short-term acute care hospital setting.

What is a Long-Term Acute Care Hospital (LTAC)?
"Long-term acute care hospital" is defined as a hospital with an average length of stay that is longer than 25 days, yet it is neither a rehabilitation nor a psychiatric hospital (according to Medicare definitions.) LTACs admit patients with medically complex diseases, with almost all the patients arriving from acute care hospitals, many directly from the ICU. LTACs usually combine aggressive therapeutic and clinical intervention in a holistic manner to achieve the best possible patient outcome for the medically complex patient.

How Did LTACs Come Into Existence?
LTAC hospitals came into existence approximately 15 years ago. They arose from the need for treatment of patients who are expected to need an extended hospital stay.

Since the mid 1980s, Medicare has reimbursed hospitals using the DRG system. The complexly ill patient, requiring an extended stay, would fall into the category of an outlier—a financial disaster for the short-term hospital. The federal government realized the need for a different type of hospital, one that is DRG exempt and would specialize in those patients requiring a comprehensive treatment approach for all their diagnoses and complications. Hence, LTAC hospitals were created.

The LTAC is equipped to treat these patients for a number of reasons. First, they are reimbursed on a cost-based basis. Second, patients admitted to an LTAC must average at least a 25-day length of stay. Third, the LTAC specializes in treatment of the catastrophic patient, and focuses its time and talents solely on those patients who otherwise would be lost in the DRG world of reimbursement.

For an example and comparison of how the LTAC differs from other methods of treatment, see the accompanying table.

So What Is the Principal Diagnosis?
Now that we have defined the LTAC and have shown its differences from other health care settings, we can return to our initial question: "How is the principal diagnosis chosen for a patient in the LTAC setting?" Does the LTAC patient present a dilemma when comparing LTAC coding to that in the acute care hospital? My answer is a decided "yes" and my answer is a decided "no." Looking back to my first year of coding in this setting, it seemed there was a definite paradox. When do you use the diagnosis from the acute care setting and extend it to the LTAC? A patient may be admitted to the LTAC on the third day following a stroke or an acute fracture. When can one say that the condition is no longer acute and the late effect codes must be used: three days? Three weeks? A claim can be made for the fact that a stroke is still evolving or the fracture takes weeks to months to heal.

The other dilemma is LTAC patients are most often admitted with an array of diagnoses currently under treatment. If the majority of them meet acute care criteria for assignment of a principal diagnosis, which one is chosen?

An experienced coder in the LTAC setting comes to rely heavily on both coding guidelines and common sense. Although these patients present with difficult case histories, the following may be helpful in determining the principal diagnosis (the assumption is made that all diagnoses meet acute care criteria and patients are treated for all conditions):

  1. The principal diagnosis at the LTAC will often differ from the principal diagnosis at the short-term acute care (STAC) facility.

    1. A. The patient is admitted with congestive heart failure and renal failure. She went into respiratory failure at the STAC and was ventilated. The patient transfers to the LTAC on the ventilator. Principal diagnosis at the acute care hospital is congestive heart failure. Principal diagnosis at the LTAC is respiratory failure; principal procedure is the ventilation.
    2. B. Patient is admitted to the STAC with diabetic foot ulcer and gangrene, undergoes a transmetatarsal amputation of the toes, develops osteomyletis at the amputation site and is transferred to the LTAC. Principal diagnosis at the STAC is diabetic foot ulcer. Principal diagnosis at the LTAC is osteomyletis.
    3. C. Patient is admitted with pneumonia, develops myelodysplastic syndrome and is transferred to the LTAC for continued treatment. Pneumonia is the principal diagnosis at the STAC; myelodsyplastic syndrome is the principal diagnosis at the LTAC.
    4. D. The patient is admitted to the STAC with CAD, undergoes a CABG surgery and presents at the LTAC with complications, including pneumonia, graft site infection and sternal wound dehiscence. Principal diagnosis at the STAC is CAD. Principal diagnosis at the LTAC is infection of the graft site.

      The main coding principals used in the above case samples are: "PDX #4—Two or more interrelated conditions, each potentially meeting the definition for principal diagnosis" and "PDX #5—Two or more diagnoses that equally meet the definition for principal diagnosis" (Reference: Coding Clinic for ICD-9-CM, Volume 7, Number 2, Second Quarter 1990, p. 4).

  2. The principal diagnosis at the LTAC may, on occasion, be the same as in the STAC.

    1. Patient is admitted to the STAC for infected stage III decubitus ulcer with MRSA. The patient is transferred to the LTAC for continued IV antibiotics and a skin flap. Principal diagnosis is the same, decubitus ulcer.
    2. Patient is admitted to the STAC with an acute myocardial Infarction (AMI), CAD, and transferred to the LTAC. Principal diagnosis at both facilities is the AMI.

      The coding principal used in this case is based on the Uniform Hospital Discharge Data Set—principal diagnosis is the condition established after study to be chiefly responsible for occasioning admission to the hospital (Reference: Coding Clinic for ICD-9-CM, Volume 2, Number 2, March-April 1985, p. 1).

  3. All admissions to the LTAC for rehabilitation have the same principal diagnosis, regardless of the reason for the admission.

    1. Patient is admitted to the STAC with a cerebrovascular accident, hemiplegia and aphasia.
    2. Patient is admitted to the STAC with a newly diagnosed fracture of the femur, undergoes reduction and fixation of fracture.

      Patient is admitted to the STAC status post fall, diagnosed with closed head injury, subdural hematoma with evacuation of the hematoma.

      Principal diagnosis on the above cases is Admission for Rehabilitation (Reference: Coding Clinic for ICD-9-CM, Volume 14, Number 3, Third Quarter 1997, pp. 11-13).

      So, go back to the initial case scenario, and based on the information provided within this article, you should be able to come up with the principal diagnosis for this case. Happy coding!

Carmen Blakeman is the director of health information management/medical staff services of LifeCare Hospital of New Orleans, which is the largest LTAC hospital in Louisiana. Blakeman has been in this position since the opening of LifeCare in late 1994, and can be reached at


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