Coding Corner

Distinguishing between stroke and TIA requires taking into consideration various definitions, including cerebral infarction, cerebral hemorrhage, aborted stroke, impending stroke and TIA.

Mrs. Brainy presented to the emergency department following acute onset of right-sided weakness and slurred speech. Her physical exam was within normal limits except for new onset of right-sided hemiparesis and a blood pressure of 190/100 mm Hg. A CT scan was ordered and interpreted as within normal limits. After a three-day hospitalization, Mrs. Brainy was discharged home with plans for physical therapy in the outpatient setting. Her principal diagnosis was reported as transient ischemic attack (TIA). What's wrong with this picture?

Distinguishing between stroke and TIA requires taking into consideration various definitions, including cerebral infarction, cerebral hemorrhage, aborted stroke, impending stroke and TIA.

Cerebral infarction. A negative CT does not preclude a diagnosis of stroke. When the CT and/or the MRI is positive for stroke, remember that ICD-9-CM codes may not be assigned based on positive findings from the diagnostic studies unless the physician documents their significance in the medical record. Diagnostic statements should differentiate between acute embolic, thrombolic or ischemic stroke if known and should pinpoint the specific cerebral artery involved. Diagnostic statements can be qualified as possible or probable in the inpatient setting.

Be sure to document residual neurological deficits that persist at the time of discharge. These deficits describe the reason for posthospital rehabilitation. Some residual deficits are also considered as complications/comorbidities (CCs) for the inpatient hospital stay. For example, hemiplegia and hemiparesis are considered CCs and should be reported when they continue to be present at the time of discharge. If the patient has experienced a previous stroke, describe the old deficits as well as the new deficits.

Cerebral hemorrhage. This condition is assigned to the same MS-DRG as cerebral infarction. Data differentiating between cases of hemorrhage versus infarction are identifiable by the different ICD-9-CM codes assigned.

Aborted stroke. This condition is coded as an infarction and is assigned to the Medicare Severity-Adjusted Diagnostic- Related Group (MS-DRG) for cerebral infarction.

Impending stroke. For ICD-9-CM coding purposes, this is reported as a TIA. If there is neurological evidence of residual deficit after 24 hours, consider reporting a diagnosis of stroke.

TIA. This describes acute or sudden onset of distinct focal neurological dysfunction persisting less than 24 hours. These transient deficits may last only a few minutes. Most symptoms of a TIA disappear within an hour, although they may persist for up to 24 hours. In some studies, 50% of TIA patients experience a stroke within the first 24 to 48 hours after the TIA.

When the reason for admission to the inpatient setting is TIA, the DRG is one of a few not impacted by the presence of a secondary diagnosis that is a major complication/comorbidity (MCC) or a CC. However, TIA, subclavian steal syndrome, and vertebrobasilar insufficiency are considered CCs when reported as a secondary diagnosis.

Basilar artery syndrome, vertebral artery syndrome and subclavian steal syndrome. These conditions are classified in the same MS-DRG as TIA.

For patients with cerebral infarction, cerebral hemorrhage and other related cerebrovascular diagnoses who are managed without thrombolytic therapy, the MS-DRG assignment is determined by the documented principal diagnosis (see Table 1).

For the stroke DRGs, the presence of a secondary diagnosis that CMS has determined to be an MCC or a CC increases the payment. Common secondary diagnoses that count as MCCs include but are not limited to:

  • acute renal failure/injury,
  • end-stage renal disease,
  • acute respiratory failure,
  • encephalopathy (specify type),
  • pneumonia (specify type),
  • acute myocardial infarction,
  • coma,
  • and cerebral edema (requiring treatment).

Common secondary diagnoses that count as CCs include but are not limited to:

  • chronic kidney disease stage 4-5,
  • malnutrition,
  • body mass index greater than 40 kg/m2,
  • hemiplegia (new),
  • late effect of previous stroke,
  • chronic systolic/diastolic heart failure,
  • atrial flutter,
  • and accelerated or malignant hypertension.

For optimal reporting of illness severity, stenosis of extracranial carotid arteries (common carotid or internal carotid artery) and intracranial arteries should be documented and coded when associated with TIA or cerebral infarct. MS-DRG 69 TIA is changed to MS-DRG 68 with the additional documentation of significant carotid stenosis, resulting in a payment of $4,651, up from $3,936, and a 0.3-day increase in geometric mean length of stay.

While the MS-DRG payment does not recognize the additional cost of thrombolytic therapy for acute MI, a DRG has been established to recognize the cost of tissue plasminogen activator (tPA) for treatment of stroke. To receive this payment, coders must assign ICD-9-CM procedure code 99.10 when tPA is administered (see Table 2) coding_table2.jpg .

Payment for thrombolytic therapy is made to the facility administering the tPA. Because tPA is often given by Hospital A with immediate patient transfer to a tertiary hospital, the American Society of Interventional and Therapeutic Neuroradiology requested that CMS provide additional payment to the receiving hospital to cover the high cost of managing these patients. CMS denied this request because “the quantification of the increased resource consumption of these patients is not currently possible in the existing ICD-9-CM coding system.”

In 2009, a new ICD-9-CM code (V45.88) was added to allow receiving hospitals to identify post-tPA patients whether they received tPA for a stroke or a myocardial infarction. Consistently reporting V45.88 as a secondary code will enable CMS to monitor costs incurred for hospitals receiving the post-tPA patient. Cerebral infarction or aborted cerebral infarction would be reported as the principal diagnosis in these cases (Inpatient Prospective Payment System Final Rules for 2009, Federal Register, Aug. 19, 2008).