Researchers studied 61 people with high blood pressure to understand a new blood test called the systemic immune-inflammatory index (SII). This test measures inflammation in the body, which can damage blood vessels and lead to heart attacks or strokes. The study found that the SII test was higher in older patients and those with kidney problems. While this test is cheap and easy to do, the researchers say it could help doctors identify which patients with high blood pressure are at greatest risk for serious complications.

The Quick Take

  • What they studied: Whether a new blood test called the systemic immune-inflammatory index (SII) can help predict which people with high blood pressure are most at risk for heart problems
  • Who participated: 61 patients with high blood pressure from a clinic in Brazil, mostly Black women, with an average age in the older adult range. About 19% also had type 2 diabetes.
  • Key finding: The SII blood test was higher in patients who were older and had worse kidney function. The test showed a strong connection with another inflammation marker called the neutrophil-lymphocyte ratio.
  • What it means for you: If you have high blood pressure, your doctor might use this simple blood test to check your inflammation levels and assess your risk. However, this is early research, and more studies are needed before this test becomes standard practice.

The Research Details

This was a cross-sectional study, which means researchers looked at a group of people at one point in time rather than following them over months or years. In 2020, researchers in Brazil collected blood samples and health information from 61 patients with high blood pressure at an outpatient clinic. They measured many different things in the blood, including cholesterol levels, kidney function, and various inflammation markers. The systemic immune-inflammatory index (SII) is calculated from three simple blood test measurements that doctors already routinely check: white blood cells, neutrophils (a type of white blood cell), and platelets (cells that help with clotting). The researchers then looked at how the SII related to other health factors like age, kidney function, and overall heart disease risk.

Understanding what causes high blood pressure complications is important because high blood pressure can lead to heart attacks, strokes, and kidney disease. Inflammation plays a hidden role in these complications, even when blood pressure is controlled. By finding a simple, inexpensive blood test that shows inflammation levels, doctors could potentially identify high-risk patients earlier and treat them more aggressively.

This study has some important limitations to consider. The sample size was small (only 61 people), so the results may not apply to larger populations. The study was done at one clinic in Brazil, mostly with Black women, so results might differ in other groups. Because this is a cross-sectional study, researchers could only show that certain factors were associated with higher SII scores—they couldn’t prove that one thing caused another. The study didn’t follow patients over time to see if higher SII scores actually predicted who would have heart attacks or strokes.

What the Results Show

The main finding was that the SII blood test score was higher in patients who were older and had worse kidney function. When researchers looked at multiple factors together, age, kidney function, and another inflammation marker called the neutrophil-lymphocyte ratio (NLR) were all positively connected to SII scores. This means that as these factors increased, the SII score tended to increase as well. Interestingly, the SII score did not correlate with the Framingham risk score, which is a traditional way doctors calculate heart disease risk. This suggests that the SII might be measuring something different about heart disease risk than traditional methods.

The study found that about 19% of participants had type 2 diabetes, and none of the participants had experienced a stroke or heart attack at the time of the study. According to the Framingham risk calculation, most of the patients in the study were classified as having high or very high risk for future heart problems. The researchers also noted that inflammation caused by organ damage appears to play an important role in the bad outcomes that can happen with high blood pressure.

This research adds to growing evidence that inflammation is important in high blood pressure complications. Previous studies have shown that inflammation markers can predict heart disease risk, but this is one of the first studies to specifically look at the SII in high blood pressure patients. The finding that SII relates to kidney function is particularly interesting because kidney damage is both a cause and a consequence of high blood pressure.

The study was small with only 61 participants, mostly Black women from one clinic, so results may not apply to other groups or larger populations. The study only looked at people at one point in time, so researchers couldn’t determine if higher SII scores actually predict who will have heart attacks or strokes in the future. The study didn’t compare the SII test to other inflammation tests to see if it’s better or worse. Additionally, the study didn’t look at whether treating inflammation would help reduce heart disease risk in these patients.

The Bottom Line

If you have high blood pressure, talk to your doctor about whether the SII blood test might be useful for your care. This test appears promising as a low-cost way to check inflammation levels, but it’s not yet standard practice. Continue following your doctor’s recommendations for managing blood pressure, taking medications as prescribed, and making healthy lifestyle changes. This research suggests that inflammation may be important to monitor, but more studies are needed before doctors widely use this test.

People with high blood pressure, especially those who are older or have kidney problems, should be aware of this research. Doctors and healthcare providers interested in new ways to assess heart disease risk should follow this research. People with diabetes and high blood pressure may find this particularly relevant. However, this research is too early to change treatment for most people—it’s mainly important for researchers and doctors to know about.

This is early-stage research, so it will likely take several years before this test becomes widely available in clinical practice. Researchers need to do larger studies following patients over time to confirm that higher SII scores actually predict heart problems. If the test proves useful, it could become available within 2-5 years, but that timeline is uncertain.

Want to Apply This Research?

  • If your doctor orders an SII blood test, track the result in your health app along with your blood pressure readings, age, and kidney function test results (creatinine or glomerular filtration rate). Record the date and numerical value so you can see trends over time.
  • Use the app to set reminders for regular blood pressure checks and kidney function tests, which appear to be connected to inflammation levels. Log any symptoms like fatigue or swelling that might relate to kidney function or inflammation.
  • If you have high blood pressure, use your app to track blood pressure readings, weight, and any blood work results your doctor orders. Note lifestyle factors like exercise, diet, and stress that might affect inflammation. Share this data with your doctor at regular visits to help them assess your overall risk.

This research is preliminary and should not be used to diagnose or treat any condition. The systemic immune-inflammatory index (SII) is not yet a standard clinical tool for assessing heart disease risk. If you have high blood pressure or concerns about your heart health, consult with your healthcare provider about appropriate testing and treatment options. This study involved a small group of patients and cannot be applied to all populations. Always follow your doctor’s recommendations for managing high blood pressure and reducing your risk of heart disease.