Biases in the observational study of beta blockers in COPD.
Suissa
S
S
Ernst
P
P
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D006801:Humans; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy*; D015983:Selection Bias
D000319:Adrenergic beta-Antagonists