Patients with chronic obstructive pulmonary disease (COPD) who become infected with the bacterium Pseudomonas aerguinosa are more likely to have worse clinical outcomes and experience more hospitalizations during the course of their disease than COPD patients who are not infected, according to researchers from Buffalo, N.Y.
The study will be presented at the ATS 2012 International Conference in San Francisco.
Bacterial bronchial infection plays a key role in the course of COPD, causing chronic inflammation as well as acute exacerbations of symptoms, and is related to increased levels of illness and mortality among COPD patients.
"Previous studies have shown that infection with P. aeruginosa is more common in patients with more severe COPD ," said study researcher Sanjay Sethi, MD, FACP, chief of the Pulmonary/Critical Care/Sleep Medicine Division at the University at Buffalo, SUNY. "In this study, we wanted to determine if infection with P. aeruginosa was associated with poorer clinical outcomes, such as hospitalizations, need for intensive care, and greater numbers of exacerbations."
The study focused on 177 patients who participated in a COPD study at the Buffalo Veterans Affairs Medical Center from March 1994 to January 2011. Study participants had clinic visits every month and additional visits during exacerbations. During each visit, clinical information and sputum samples were taken. Patients with less than six months of follow-up were excluded from the study.
For this analysis, study participants were divided into two groups: those whose sputum samples showed evidence of P. aeruginosa (PA+) infection and those whose samples showed no evidence of the bacteria (PA-). In addition, follow-up times were divided into two phases, Phase 1 denoting the time period prior to acquiring P. aeruginosa and Phase 2 covering the time period after the bacteria had been identified in the sputum.
"As COPD progresses, hospitalizations and exacerbations tend to increase and we had to account for that in our analysis. Therefore, we matched PA+ subjects with PA- subjects having similar duration of follow-up in the study," Dr. Sethi said. "Rates of events, including hospitalizations, ICU admissions and COPD exacerbations, and relative risks of having at least one event were compared in the two phases within and between the two groups."