Abstract
Acute exacerbations of COPD (AECOPD) and community acquired pneumonia (CAP) often coexist. Although Chest X-rays may differentiate between both diagnoses, chest X-rays are known to underestimate the incidence of CAP in AECOPD. In this exploratory study, we prospectively investigated the incidence of infiltrative changes using low-dose CT-scan (LDCT). Additionally, we investigated whether clinical biomarkers of CAP differed between patients with and without infiltrative changes.
Methods Patients with AECOPD in which pneumonia was excluded using chest X-ray underwent additional LDCT-thorax. The images were independently read by two radiologists, a third radiologist was consulted as adjudicator. C-reactive protein (CRP), procalcitonin (PCT), and serum Amyloid A (SAA) at admission were assessed.
Results Of the 100 patients included, 24 patients had one or more radiographic abnormalities suggestive of pneumonia. The inter-observer agreement between two readers (Cohen's Kappa) was 0.562 (95%CI 0.371–0.752; p<0.001). Biomarkers were elevated in the group with radiological abnormalities compared to the group without abnormalities. Median CRP was 76 (IQR 21.5–148.0) mg·L−1 compared to 20.5 (IQR 8.8–81.5) mg·L −1 (p=0.018), median PCT was 0.09 (IQR 0.06–0.15) µg·L−1 compared to 0.06 (IQR 0.04–0.08) ug·L−1 (p=0.007), median SAA was 95 (7–160) µg·mL−1 compared to 16 (IQR 3–89) µg·mL−1 (p=0.019). Sensitivity and specificity for all three biomarkers were moderate for detecting radiographic abnormalities by LDCT in this population. The area under the ROC curve was 0.66 (95% CI: 0.52–0.80) for CRP, 0.66 (95%CI: 0.53–0.80) for PCT, and 0.69 (95%CI: 0.57–0.81) for SAA.
Conclusion LDCT can detect additional radiological abnormalities which may indicate acute-phase lung involvement in patients with AECOPD without infiltrate(s) on the chest X-ray. Despite C-reactive protein, procalcitonin and serum amyloid A being significantly higher in the group with radiological abnormalities on LDCT, they proved unable to reliably detect or exclude CAP. Further research is warranted.
Footnotes
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- Received October 14, 2021.
- Accepted April 6, 2022.
- Copyright ©The authors 2022
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