A simple blood test called the Prognostic Nutritional Index (PNI) can predict which patients will develop new blockages in their leg arteries after surgery, according to a 2026 study of 227 patients. Gram Research analysis shows PNI correctly identified 73% of patients who developed blockages within 6 months, outperforming three other similar blood tests. However, this finding is preliminary and requires testing in larger patient groups before doctors should use it routinely in clinical practice.
Doctors use blood tests to predict which patients might develop blocked arteries after leg surgery. According to Gram Research analysis, a test called the Prognostic Nutritional Index (PNI) was better at predicting problems than three other similar tests. In a study of 227 patients who had surgery to open blocked leg arteries, the PNI test correctly identified 73% of patients who would develop new blockages within 6 months. This finding could help doctors decide which patients need closer monitoring or different treatment approaches after their surgery.
Key Statistics
A 2026 cohort study of 227 patients found that the Prognostic Nutritional Index (PNI) achieved 73% accuracy in predicting new artery blockages within 6 months after leg artery surgery, compared to 63%, 58%, and 57% for three alternative blood tests.
According to research reviewed by Gram, among 227 patients who had surgery to open blocked leg arteries, 34.8% developed new blockages within 6 months, and the Prognostic Nutritional Index was the strongest predictor of this outcome.
A 2026 study found that adding the Prognostic Nutritional Index to standard clinical prediction improved accuracy from 67% to 78% for identifying patients at risk of restenosis after leg artery surgery.
Research shows that for every unit decrease in Prognostic Nutritional Index score, the risk of developing new artery blockages increased 2.72 times in a study of 227 leg artery surgery patients.
The Quick Take
- What they studied: Whether simple blood tests can predict which patients will develop new blockages in their leg arteries after surgery to open blocked vessels
- Who participated: 227 patients who had successful surgery to open chronically blocked superficial femoral arteries (major blood vessels in the thigh) between 2015 and 2021
- Key finding: The Prognostic Nutritional Index (PNI), a blood test measuring protein and immune cell levels, was the best predictor of new blockages. It correctly identified problems 73% of the time, compared to 63%, 58%, and 57% for three other tests.
- What it means for you: If you have leg artery surgery, your doctor might use a simple blood test to estimate your risk of developing new blockages. This could help determine how often you need follow-up appointments. However, this research is preliminary and needs testing in larger patient groups before becoming standard practice.
The Research Details
Researchers looked back at medical records from 227 patients who had surgery to open blocked leg arteries between 2015 and 2021. They measured four different blood tests on each patient before surgery and then tracked whether new blockages developed within 6 months using imaging scans. The four tests measured different combinations of inflammation markers (C-reactive protein), protein levels (albumin), and immune cells (lymphocytes). The researchers compared how well each test predicted which patients would develop new blockages.
To ensure fair comparison, the researchers used statistical methods to account for other factors that might affect blockage risk, such as age, smoking status, and the severity of the original blockage. They also used a technique called bootstrap validation, which is like testing the results multiple times with slightly different data samples to make sure the findings are reliable.
The study focused specifically on one type of leg artery (the superficial femoral artery) with complete blockages that had been present for a long time. This narrow focus means the results apply specifically to this patient group and may not work the same way for other types of blockages or arteries.
After surgery to open blocked arteries, some patients develop new blockages (restenosis) that can require additional treatment. Being able to predict which patients are at highest risk would help doctors provide better follow-up care. A simple blood test would be much cheaper and easier than repeated imaging scans. This study compared four different blood tests to find which one works best for this specific purpose.
This was a well-designed retrospective study with 227 patients, which is a reasonable sample size for this type of research. The researchers used proper statistical methods including adjustment for other risk factors and internal validation testing. However, the study has limitations: it looked back at past data rather than following patients forward, it was conducted at a single center, and the results need to be confirmed in other patient groups before doctors should use this test in routine practice. The authors themselves noted these limitations and called for external validation.
What the Results Show
Among 227 patients who had surgery to open blocked leg arteries, 79 patients (34.8%) developed new blockages within 6 months. The Prognostic Nutritional Index (PNI) was the best predictor of this outcome. When tested using a statistical method called ROC analysis, PNI achieved an accuracy score of 0.728 on a scale where 1.0 is perfect and 0.5 is no better than guessing. This compared favorably to the other three tests: CONUT scored 0.625, CALLY scored 0.582, and CAR scored 0.568.
When researchers adjusted for other factors that might affect blockage risk (such as age, smoking, and lesion characteristics), PNI remained strongly associated with new blockages. For every unit decrease in PNI score (indicating worse nutritional status and more inflammation), the risk of restenosis increased 2.72 times. The CONUT test also remained significant with a 1.61 times increased risk per unit decrease, but the other two tests did not show independent associations after adjustment.
When PNI was added to a basic clinical prediction model, it improved the model’s accuracy from 0.670 to 0.782. This improvement held up even when the researchers tested it using bootstrap validation, a method that simulates how the test would perform in new patient populations. The improvement was substantial enough that it could meaningfully change clinical decision-making about which patients need closer monitoring.
The CONUT score, which measures nutritional status and inflammation, also remained independently associated with restenosis after statistical adjustment. However, its predictive power was notably weaker than PNI. The other two tests (CALLY and CAR) did not show independent associations with restenosis when other factors were controlled for, suggesting they may not be useful for this specific prediction task. The study also found that the combination of clinical factors alone (without any blood test) had moderate predictive ability, but adding PNI substantially improved predictions.
Previous research has shown that inflammation and nutritional status are associated with poor outcomes after vascular surgery. This study is the first to directly compare these four specific blood-based indices for predicting restenosis after leg artery surgery. The finding that PNI outperforms the other three tests suggests that the specific combination of measurements in PNI (albumin, total lymphocyte count, and body weight) may be particularly relevant for predicting this complication. The results align with general knowledge that both malnutrition and inflammation increase surgical complications.
This study has several important limitations. First, it was retrospective, meaning researchers looked back at past medical records rather than following patients forward prospectively. Second, it included only patients from a single medical center, so results may not apply to other hospitals or geographic regions. Third, the study focused specifically on one type of artery blockage (superficial femoral artery chronic total occlusion), so findings may not apply to other types of vascular disease. Fourth, the study did not include external validation in a separate patient population, which is necessary before a test can be recommended for routine clinical use. Finally, the authors did not establish that PNI is clinically validated or ready for real-world use; they explicitly stated that external validation is required.
The Bottom Line
Based on this research, the Prognostic Nutritional Index shows promise as a tool for predicting restenosis after leg artery surgery. However, it is not yet ready for routine clinical use. Patients who have had leg artery surgery should continue following their doctor’s recommended monitoring schedule. Doctors may consider PNI as one factor among many when assessing individual patient risk, but should not rely on it alone. Further research in larger, diverse patient populations is needed before PNI becomes standard practice.
This research is most relevant to vascular surgeons and interventional radiologists who treat patients with blocked leg arteries. Patients who have had or are planning to have surgery for leg artery blockages may find this information helpful for understanding their risk factors. However, individual patients should discuss their specific situation with their doctor rather than trying to interpret PNI scores on their own. This research does not apply to people without leg artery disease or those with blockages in other blood vessels.
The restenosis (new blockage) that this test predicts occurs within 6 months of surgery. If a patient has a high PNI score indicating risk, they would likely need imaging follow-up within this timeframe. However, this research does not establish how quickly patients should be monitored or what interventions should be used based on PNI results.
Frequently Asked Questions
What is the Prognostic Nutritional Index and how does it predict artery blockages?
The Prognostic Nutritional Index (PNI) is a blood test that measures albumin (a protein), lymphocyte count (immune cells), and body weight. These measurements reflect nutritional status and inflammation. A 2026 study found PNI correctly predicted new artery blockages 73% of the time after leg surgery.
Should I ask my doctor about the Prognostic Nutritional Index after leg artery surgery?
This research is preliminary and not yet standard practice. Discuss with your vascular surgeon whether PNI testing might be useful for your individual situation. Continue following your doctor’s recommended monitoring schedule regardless, as this test is not yet clinically validated for routine use.
How common are new blockages after leg artery surgery?
In this study of 227 patients, about 35% developed new blockages within 6 months of surgery to open blocked leg arteries. This is why doctors recommend regular follow-up appointments and imaging after the procedure.
Can I improve my Prognostic Nutritional Index score to prevent blockages?
Since PNI measures nutritional status and inflammation, maintaining good nutrition, healthy weight, and managing inflammation through exercise and disease control may help. However, this research does not prove that improving PNI scores prevents blockages, so discuss nutrition strategies with your doctor.
Is this blood test better than imaging scans for detecting new blockages?
No. The PNI blood test predicts risk but cannot detect actual blockages. Imaging scans like ultrasound or CT are needed to confirm new blockages. PNI could help doctors decide which patients need more frequent imaging follow-up.
Want to Apply This Research?
- If you have had leg artery surgery, track your follow-up appointment dates and imaging scan results. Record any symptoms like leg pain, weakness, or coldness that might indicate new blockages. Note your albumin and lymphocyte levels from blood tests if your doctor provides them.
- Work with your doctor to maintain good nutrition before and after leg artery surgery, as nutritional status appears to influence blockage risk. Maintain a healthy weight, eat adequate protein, and follow any dietary recommendations your doctor provides. Manage inflammation through exercise, smoking cessation, and controlling conditions like diabetes.
- Set reminders for scheduled follow-up appointments after leg artery surgery. Keep records of blood test results and imaging findings. Report any new symptoms to your doctor promptly. If your doctor mentions nutritional or inflammatory markers, ask how they relate to your individual risk.
This article summarizes research findings and should not be used for self-diagnosis or to replace medical advice from your doctor. The Prognostic Nutritional Index is not yet an established clinical tool for routine use. If you have had or are considering leg artery surgery, discuss your individual risk factors and monitoring needs with your vascular surgeon or interventional radiologist. This research applies specifically to patients with chronic total occlusions of the superficial femoral artery and may not apply to other types of vascular disease. Always follow your doctor’s recommended follow-up care and imaging schedule.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.