To the Editor.
—We read with interest the meta-analysis of Mullen et al1 of case-control studies of β-agonists and asthma death, and we are in agreement with its methodology and general conclusions. The meta-analysis shows that the results of Spitzer et al2 are significantly different from those reported by all other researchers, whereas the finding of our New Zealand case-control studies3-5 are consistent with those of other researchers.6,7 Mullen et al1 suggest that the findings of Spitzer et al2 may be different because they focused on an older age-group. An alternative explanation is that the findings of Spitzer et al2 are inconsistent because of methodological flaws in the study.Their study was based on patients who had received 10 or more prescriptions for one or more asthma drugs during a 10-year period, and patient medication was then assessed for the previous 12 months
Pearce N, Crane J, Burgess C, Beasley R. β-Agonist Use and Death from Asthma. JAMA. 1994;271(11):822-823. doi:10.1001/jama.1994.03510350029021