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3 Reasons to Use Shock Index Assessment With Stroke Patients

Analysis  |  By Christopher Cheney  
   November 27, 2018

In less than 5 minutes, the Shock Index assessment can gauge the severity of a patient's condition.

Stroke is a deadly and expensive-to-treat condition that kills about 140,000 Americans each year, with annual costs for healthcare services and medications estimated at $34 billion, according to the Centers for Disease Control and Prevention.

But what can clinical leaders do to mitigate deaths and healthcare costs due to stroke?

For stroke patients prior to hospital admission, a simple and inexpensive assessment can guide treatment decisions and predict a range of outcomes, recent research shows.

A Shock Index (SI) calculated as heart rate divided by systolic blood pressure can quickly and inexpensively assess stroke patients, researchers wrote recently in Journal of the American Heart Association.

"Our study shows that SI is a significant predictor of important patient-related acute stroke outcomes including mortality, acute hospital length of stay, discharge destination, ambulatory status at the time of discharge, and poststroke disability," they wrote.

The researchers collected data from more than 425,000 patients. Most of the patients (89.7%) had experienced ischemic stroke.

Here are three reasons to use the Shock Index assessment on your stroke patients.

1. It's a good predictor of outcomes
 

The lead author of the research says the SI is a powerful predictive tool.

"SI appears to be a very good predictor of several stroke outcomes immediately after stroke—not just mortality but also for dependency and discharge destination other than home," Phyo Kyaw Myint, MD, of the Institute of Applied Health Sciences at University of Aberdeen's School of Medicine in the United Kingdom, told HealthLeaders.

2. It does not require expensive equipment
 

The SI is particularly valuable for healthcare facilities that struggle to fund expensive assessment technology or to train staff on the National Institutes of Health Stroke Scale (NIHSS), he said.

"SI is calculated based on the heart rate and blood pressure, and these measurements are usually done by trained clinical staff. It doesn't require any special equipment or computer system to calculate SI. It is easy to perform and takes less than 5 minutes. Therefore, SI as an alternative tool to assess the prognosis of stroke patients at the time of assessment is extremely useful in low-resource settings such as rural hospitals and low-income settings," Myint said.

3. It can be used in clinical settings now
 

Although Myint and his research coauthors are calling for more research on the SI, he says the assessment tool is appropriate for use in clinical settings now.

"As this is a physiological index, it can be applied in clinical practice immediately. We stated more research is needed in the sense that, to make change in practice, large numbers of studies are required before we can start to see changes. Therefore, our findings should be replicated in different populations as well as in different healthcare settings to demonstrate the external validity of the findings to convince clinicians of the robustness of the SI as a useful prognostic assessment," Myint says.

As more studies are conducted, patients can benefit from clinicians using the SI, he says.

"In the interim, we would recommend that stroke patients with high SI should be carefully monitored and clinicians should be made aware of their likely poor diagnosis to ensure appropriate management strategies can be implemented and realistic expectations of the outcome can be communicated with the patient's relatives," Myint said.

SI by the numbers
 

Myint and his coauthors divided the patients in their study into three SI cohorts: patients with SI values greater than 0.7, patients with SI values between 0.5 and 0.7, and patients with SI values less than 0.5.

Patients with SI values greater than 0.7 were at higher risk for poor outcomes and comorbidities, the researchers found.

For example, compared to patients with lower SI values, patients with high SI values were prone to have peripheral vascular disease and heart failure. "They had significantly higher heart rate and lower systolic BP on admission and were associated with significantly higher rates of poor outcomes for all outcomes examined," the researchers wrote.

The researchers found SI greater than 0.7 was associated with several poor outcomes.

  • There was high mortality relative to other stroke patients. In-hospital mortality was 11.0% for patients with SI greater than 0.7 compared to 5.9% for other stroke patients.
     
  • For patients with high SI values, 55.7% were not able to ambulate independently, compared to 48.0% of other stroke patients.
     
  • Other poor outcomes for patients with high SI values included longer hospital length of stay and higher likelihood of disability.

The SI provides clinicians with a powerful stroke assessment tool at low cost, the researchers wrote.

"This information may be useful in clinical practice for managing stroke patients, to identify those with high risk of poor outcomes from the point of contact, particularly if NIHSS is not available, and to better inform patients and their significant others about the prognosis of these important outcomes," they wrote.

Christopher Cheney is the senior clinical care​ editor at HealthLeaders.


KEY TAKEAWAYS

Shock Index is easy to calculate—heart rate divided by systolic blood pressure.

The assessment tool can forecast several outcomes for stroke patients, including mortality, hospital length of stay, and discharge destination.

Shock Index is a powerful tool with low cost.


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