Fibrinogen Protein Levels May Help Predict Exacerbation Outcomes
Levels of the protein fibrinogen in the blood can be used to assess inflammation and the risk of non-invasive ventilation failure during acute exacerbations in people with chronic obstructive pulmonary disease (COPD), according to a new study.
Fibrinogen is an inflammation-associated protein that is known as a biomarker for assessing the severity of COPD.
“The current study suggested that circulating fibrinogen value during [acute exacerbation of] COPD strongly correlated with traditional inflammatory markers and can reflect the severity of systematic inflammatory response,” the researchers wrote, noting that high levels of fibrinogen may denote that antibiotics are needed.
“Moreover, fibrinogen was a better marker for predicting [non-invasive ventilation failure] than traditional inflammatory ones, and this indicated that it might be used for identifying [acute exacerbation of] COPD patients who may not benefit from [non-invasive ventilation],” they added.
The study, “Fibrinogen, a Promising Marker to Evaluate Severity and Prognosis of Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Retrospective Observational Study,” was published in the International Journal of Chronic Obstructive Pulmonary Disease.
A large body of evidence has shown that higher fibrinogen levels are tied to worse outcomes — such as more hospitalizations and higher mortality rates — among people with COPD.
However, whether fibrinogen levels can predict the severity of COPD exacerbations — times when symptoms suddenly worsen — has not been as extensively researched.
Can fibrinogen levels predict exacerbation severity?
To learn more, scientists at Beijing Chao-Yang Hospital, in China, analyzed data from people with COPD who experienced a disease exacerbation. The analysis included 535 patients treated at their center from January 2016 to June 2021.
“This study aimed to explore whether circulating fibrinogen could be used as a surrogate to measure the severity and predict the prognosis of” acute exacerbations of COPD, the team wrote.
Among the patients analyzed, 86 had circulating fibrinogen levels higher than 4 g/L; normal fibrinogen levels are between 2-4 g/L. These high-fibrinogen patients were comparable to the overall group in terms of age, sex, body mass index (BMI), and smoking history.
However, levels of several inflammatory markers were increased among the patients with these high fibrinogen levels. They also had markedly faster heart and breathing rates, and they more commonly had co-occurring health problems such as emphysema, pneumonia, or clotting disorders.
According to the researchers, the study “demonstrated that [acute exacerbation of] COPD patients with [greater than] 4 g/L fibrinogen had a more robust inflammatory response and that it is possible that fibrinogen could be used as a marker of ongoing airway inflammation.”
During exacerbation treatment, 223 of the patients in the study — more than 40% — received non-invasive ventilation. In all, 79.4% successfully responded to non-invasive ventilation and 20.6% failed ventilation. Such failure was described as a patient experiencing a substantial worsening in clinical status despite ventilation.
The patients in whom ventilation failed had significantly higher fibrinogen levels than those for whom ventilation was successful, or who did not require ventilation. These individuals also had higher levels of inflammatory markers.
The researchers used a statistical analysis called area under the receiver operating characteristic curve, or AUC, to evaluate whether fibrinogen levels could predict the risk of ventilation failure. AUC values can range from 0.5 to 1, with higher values reflecting a better ability to differentiate between two groups (in this case, ventilation failure or not).
The calculated AUC value for fibrinogen was 0.899, which essentially means that the accuracy of this biomarker in detecting patients who failed ventilation was close to 90%. This was notably higher than for established inflammatory markers such as C-reactive protein or immune cell levels.
Because non-ventilation failure is by definition associated with worse outcomes for patients, the researchers suggested that measuring fibrinogen levels “might be used in identifying those at great risk and who may therefore benefit from more aggressive treatment like early intubation.”
The scientists stressed that this study has a relatively small sample size and was conducted at a single center, so more research is needed to validate these findings. Another noted limitation was that most patients did not have lung function measurements (spirometry) available from the time of their exacerbation.
“Further study with a larger sample is needed to determine whether using fibrinogen as a biomarker to assess [acute exacerbations of] COPD individuals could actually result in clinical benefit,” the researchers concluded.