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How Much Did Biases in the Study of Chronic Obstructive Pulmonary Disease Medications and Mortality Affect the Outcome?
- Samy Suissa, PhD; and
- Pierre Ernst, MD, MSc
- From Jewish General Hospital, Montréal, Québec H3T 1E2, Canada.
TO THE EDITOR:
Lee and colleagues (1), using an observational study design, report that the use of ipratropium is associated with a 34% increase in the risk for cardiovascular death and that the use of inhaled corticosteroids (ICSs) is associated with a 20% reduction in all-cause mortality in patients with chronic obstructive pulmonary disease (COPD). Some methodological considerations should be addressed in judging the validity of these findings.
The excess risk for cardiovascular death seen with ipratropium (odds ratio, 1.34 [95% CI, 1.22 to 1.47]) may be due to the marked imbalance between case patients …
