The Annals of Internal Medicine has published the findings of an observational study that aimed to examine the association between various respiratory medications and risk for death in patients with newly diagnosed chronic obstructive pulmonary disease (COPD).
The study identified 32,130 case patients and matched these to 320,501 control cases. 11,897 records contained cause-of-death data, 2,405 case patients had respiratory deaths and 3,159 case patients had cardiovascular deaths. Records were also assessed for exposure to inhaled corticosteroids, ipratropium, long-acting beta-agonists, and theophylline in the 6 months preceding death.
The odds ratios (OR) for all-cause mortality for each drug were as follows:
- 0.80 (95% CI, 0.78 to 0.83) for inhaled corticosteroids
- 1.11 (95% CI, 1.08 to 1.15) for ipratropium
- 0.92 (95% CI, 0.88 to 0.96) for long-acting beta-agonists
- 1.05 (95% CI, 0.99 to 1.10) for theophylline
In addition, ipratropium was associated with an increased risk of cardiovascular death (OR, 1.34 [CI, 1.22 to 1.47]) and inhaled corticosteroids were associated with reduced risk for cardiovascular death (OR, 0.80 [CI, 0.72 to 0.88]).
It should be noted that the study did not collect data or correct for smoking status or lung function. The observed differences may be explained by differences in these variables and the authors therefore conclude that, "the possible association between ipratropium and elevated risk for all-cause and cardiovascular death needs further study".
Action: Clinicians should be aware of these findings and the limitations of this analysis. Patients can be reassured that cause and effect has not been demonstrated and that more research is required to investigate these findings. Clinicians should continue to implement the current NICE Guideline.