Levels of certain cytokines form different, disease-specific, early inflammatory patterns in patients with community-acquired pneumonia (CAP) on a background of COPD than in those who do not have a history of COPD, according to research online in the journal Chest. The authors do not think the differences can be fully attributed to corticosteroid use in COPD patients.
"We showed that, on the first day of hospitalization, the systemic response to bacterial infection (not completely corticosteroid mediated) in patients with COPD is lower, especially in terms of levels of TNF (tumor necrosis factor)-α, IL(interleukin)-1, and IL-6 cytokines," the authors wrote. However, they note that "Our study is not intended or statistically powered to evaluate the clinical and prognostic effects of a different, early inflammatory response between patients with CAP only and those with CAP and COPD."
Investigators analyzed clinical, microbiologic, and immunologic data from 117 patients with CAP plus COPD and 250 individuals with only CAP. The use of inhaled and oral corticosteroids was recorded, and pneumonia severity scores were calculated on the Pneumonia Severity Index (PSI) and CURB-65 (confusion, urea plasma level, respiratory rate, blood pressure, age over 65) scale.
When hospitalized initially, patients with CAP plus COPD had significantly lower serum levels of TNF-α, IL-1, and IL-6 compared with the CAP-only group. There was no difference in the levels of C-reactive protein, procalcitonin, IL-8, and IL-10.
The most frequent pathogen in both groups was streptococcus pneumoniae, though patients with COPD and CAP were more likely to have a microbiologic diagnosis of Pseudomonas aeruginosa then patients with CAP only. This ceased to be true when COPD patients using corticosteroids were discounted.
In patients with CAP and COPD, the PSI and CURB-65 may not be good markers of CAP severity, and that "the low levels of circulating inflammatory biomarkers may have a nondetrimental effect on the hospital course and prognosis of these patients," according to the authors.