This dataset comes from a systematic review of randomized
controlled trials on pharmacologic treatments for chronic
obstructive pulmonary disease (COPD) (Baker et al., 2009).
The primary outcome, occurrence of one or more episodes of COPD
exacerbation, is binary (yes / no). For this outcome, five drug
treatments (fluticasone, budesonide, salmeterol, formoterol,
tiotropium) and two combinations (fluticasone + salmeterol,
budesonide + formoterol) were compared to placebo. The authors
considered the two combinations as separate treatments instead of
evaluating the individual components.