Rising immune cell ratio can risk survival with CKD-related PH
Study links higher neutrophil-to-lymphocyte ratio in blood to poorer outcomes
Elevated blood levels of an inflammatory biomarker called the neutrophil-to-lymphocyte ratio (NLR) were associated with a higher risk of death among people with pulmonary hypertension (PH) related to chronic kidney disease (CKD), according to a recent report.
“NLR, which is a convenient and inexpensive parameter, may be a novel marker of adverse outcomes among these patients,” the researchers wrote. “Future studies are warranted to determine whether patients with CKD-related PH and elevated NLR levels will have benefits from anti-inflammatory therapies.”
The study, “Neutrophil-to-lymphocyte ratio predicts poor prognosis in patients with chronic kidney disease–related pulmonary hypertension: A retrospective study,” was published in Medicine.
NLR levels and risks of PH with chronic kidney disease not well known
Pulmonary hypertension refers to a group of conditions marked by excessive pressure in the pulmonary arteries, which carry blood from the heart to the lungs. Disease symptoms range from breathing problems to fatigue and chest pain, and patients are at risk of heart failure.
PH can occur as a complication of other health conditions including kidney disease. In people with CKD, also having pulmonary hypertension is associated with more advanced disease and a poorer prognosis.
Inflammation is known to play an important role in both PH and CKD with various inflammatory markers linked to disease progression.
An elevated NLR increasingly has been recognized as an important inflammatory marker of potentially poor outcomes in several diseases. This measure takes into account the ratio between two immune cell types, neutrophils and lymphocytes.
Neutrophils are part of what’s called the innate immune system, and serve as first responders to a potential threat. Lymphocytes, a part of the adaptive immune system, work more slowly but are able to recognize threats they’ve seen before and launch a more targeted attack.
Previous research found a link between an elevated NLR and a worse prognosis in people with certain other types of PH, but the relationship between the biomarker and outcomes in CKD-related PH have not been explored.
Researchers in China set out to determine possible links by reviewing the medical records of 176 adults with CKD-related PH treated at a hospital in Hunan province between 2012 and 2020.
The majority of patients, 133 of the 176, were in CKD stage 5, the most advanced disease stage where kidney function is severely reduced and a person is either in or very near to kidney failure. None had yet received a kidney transplant or dialysis, a procedure used to mimic the kidney’s functions when they fail.
Most patients (151) also were found to have mild PH. Still, those with stage 5 CKD had significantly higher pulmonary artery pressure, an indicator of PH severity, than did people in earlier stages of kidney disease.
Overall, 36 people had high NLR levels — above 4.3 — while the remaining 140 had an NLR at or below that cutoff level.
Risk of death rose with rise in neutrophil-to-lymphocyte ratio in blood
People with a high NLR, on average, were found to have lower levels of hemoglobin, a protein that helps red blood cells carry oxygen, than patients with lower NLR levels.
They also showed signs of poorer kidney function, including higher levels of creatinine, a waste product normally filtered from the blood by the kidneys, and a lower estimated glomerular filtration rate (eGFR), which estimates how well the kidneys are filtering waste. Overall, an increasing NLR correlated with a decreasing eGFR.
A rising NLR also associated with higher blood levels of C-reactive protein, a standard inflammatory biomarker.
Over a median follow-up of 32.5 months (more than 2.5 years) 23 patients died. An NLR over 4.3 significantly associated with poorer survival, raising the risk of death by more than three times compared with people whose NLR levels were below that cutoff value.
Across different types of statistical analyses, a higher NLR consistently linked to a worse prognosis, even when controlling for factors such as age, the presence of diabetes, eGFR measures, and PH severity.
“In conclusion, our study suggested that an increased NLR was independently associated with a higher risk of all-cause mortality in hospitalized patients with CKD-related PH,” the researchers wrote.
They noted this analysis was limited by its retrospective nature and data covering a relatively small group of patients from a single hospital.
“Therefore, a large-scale prospective validation study will be needed to confirm the results,” they concluded.
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