NEW YORK (Reuters Health) – Inhaled anticholinergics may increase the risk of community-acquired pneumonia in asthma patients, results of a Spanish case-control study suggest.
The findings, published online June 4th in the European Respiratory Journal, also bolster evidence for a link between inhaled steroids and pneumonia in people with chronic obstructive pulmonary disease (COPD).
Whether or not the inhaled drugs play a causal role in pneumonia is still uncertain, Dr. Jordi Almirall, who led the research, told Reuters Health by e-mail.
He emphasized that this is first study to suggest a relation between anticholinergics and pneumonia in asthma patients. If the findings are confirmed, doctors may want to consider substituting drugs or using smaller doses, he said.
Between 1999 and 2000, Dr. Almirall, of Hospital de Mataro in Spain, and colleagues identified 1,336 cases of community-acquired pneumonia at primary care centers, and matched them to 1,326 controls by age, sex and treatment center.
In the pneumonia group, 35% of patients had chronic bronchitis, COPD, or asthma, compared to 18% of control subjects.
Among those with COPD, 49% in the pneumonia group and 24% in the control group had used inhaled steroids regularly during the past year. On multivariate analysis adjusting for baseline disease severity, comorbidities and asthma, inhalers were associated with an odds ratio of 3.26 (p=0.038) for pneumonia. Smoking also significantly increased the odds of pneumonia (OR, 4.23).
Among asthma patients, 5% in the pneumonia group and 1% in the control group had used an inhaled anticholinergic. The use of ipratropium bromide was associated with an adjusted OR of 8.8 for pneumonia (p=0.048). Pneumococcal vaccine had a significant protective effect (OR, 0.35).
Inhalers were not associated with pneumonia in chronic bronchitis patients.
The researchers speculate that effect of anticholinergic agents may be related to a reduction in ciliary motility and a decrease in mucous secretion, thus favoring pathogen growth. Muscarinic antagonism may also reduce neutrophil infiltration of the airways, impairing the immunological response to infection.
As for steroids,