Bourne, Simon Charles
The effect of smoking on the severity, and mechanisms of acute exacerbations of chronic obstructive pulmonary disease (COPD).
COPD (Chronic Obstructive Pulmonary Disease) worldwide has a prevalence of
10% in men and 8.5% in women. Exacerbations of COPD account for
approximately 10% of all acute medical admissions. Projected prevalence
figures suggest that by 2020 COPD will be the third leading cause of mortality
worldwide thus imposing a significant burden on healthcare resources in the
future. Acute exacerbations are not only responsible for a decline in the
patient’s quality of life, but have a major socioeconomic impact. Following a
pilot study that showed current smokers recover lung function much more
slowly from their exacerbation than ex smokers, I initiated a properly powered
prospective study to investigate the difference between the two groups.
A total of 58 patients admitted with acute infectious exacerbations of COPD
were recruited to the study to determine the effect of smoking status on their
exacerbation. Throughout the admission lung function was measured. Sputum
was cultured for bacteria, and PCR used to detect viral infection. Blood and
sputum cells were analyzed by flow cytometry. Serum was collected for CRP
Ex-smokers recovered significantly more quickly than current smokers in all
spirometric parameters (P<0.01), and were discharged sooner (mean 3.08 vs
5.59 days, P<0.001). Sputum culture was positive for more pathogenic bacteria
in current smokers, especially H. influenzae, which was associated with a
significantly higher CRP rise (p<0.05) than any other organism. CD8+ T cells
predominated in the sputum of ex-smokers while CD4+ T cells were the
dominant cell type in current smokers (p<0.01).
Current smoking is a risk factor for more severe exacerbations, delayed
recovery and prolonged hospitalization. This may result from a variety of factors
including bacterial, immune mediated responses and systemic inflammation.
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