A clinical risk assessment using three other variables does much better, according to a new study.
Lung function tests and a history of past exacerbations combined with patient-reported symptoms are a better predictor of future exacerbations in COPD than routine blood biomarkers, a study suggests.
To date, no blood biomarker has provided a robust predictive value for exacerbations in COPD. This remains the case, after a study, published in Respiratory Medicine, investigated the predictive value of routine blood biomarkers alongside clinical characteristics as risk factors for exacerbations in COPD.
The multicentre observational study looked at clinical risk factors and possible blood biomarkers for exacerbations among COPD patients with mild, moderate and severe disease over 12 months.
Although the biomarkers did not provide additional information to evaluate the risk of exacerbations, the study produced an equation of risk combining three clinical variables that were associated with risk of exacerbation.
Clinical history, COPD Assessment Test questionnaires and spirometry tests were taken at baseline, along with routine blood biomarkers including blood cell count, fibrinogen and C-reactive protein. Follow-up visits were scheduled at six and 12 months. At both points, patients reported the number and severity of exacerbations they had experienced.
Of the 325 patients involved in the study, nearly half presented with at least one exacerbation in the 12-month follow-up period.
Those patients had more respiratory symptoms at baseline, especially wheezing, sputum and dyspnoea, and scored worse on their CAT than the patients who had no exacerbations.
Comparing patients who had at least one exacerbation to those who experienced none, the researchers developed a new multifactorial risk assessment based on three easy-to-obtain clinical variables: the patient’s CAT score, their history of previous exacerbations in the last year and lung function (measured by FEV1).
Patients with a higher CAT score (>15), lower FEV1 (<55%) and at least one exacerbation the previous year, had a 76% probability of having an exacerbation the following year. For patients who did not fit any of those criteria, reflecting better lung function and more controlled disease, the risk of a future exacerbation was just 17%.
Respiratory physician Professor Christine Jenkins from The George Institute of Global Health in Sydney said that in the three-way risk assessment, a CAT score of 15 or over was a very practical threshold because that score alone wouldn’t otherwise identify a patient severely affected by their COPD.
“This is only a mild-to-moderate level of impact and yet it’s telling you something about the symptom burden and risk of exacerbations,” Professor Jenkins said.
The study also demonstrated the importance of measuring lung function in patients with COPD, she said. “Whether your patient has an FEV1 of 45% or 75% makes a big difference [to their risk of exacerbations].”
Professor Jenkins said there were other useful indicators of exacerbation risk that could be readily assessed.
“Measuring the frequency of a patient’s reliever use might also give you a very good handle on whether somebody is at risk of an exacerbation, especially in the near term, as it signifies worsening symptoms,” she said.
The study authors concluded that their results “confirm that a history of exacerbations is the strongest predictor for future risk of exacerbations”.
