Reanalysis Negates Recommendation for N95 Respirators

Results of an Australian study—which were used by the Institute of Medicine and the CDC to recommend fitted N95 respirators to prevent influenza among healthcare workers—have been retracted. The retraction was made in a surprise announcement over the weekend, reported MedPage Today, at the annual meeting of the Infectious Diseases Society of America in Philadelphia.

A reanalysis of the Australian study was prompted by initial criticism of the study's design, which did not use randomly selected hospitals as a control group. Follow-up statistical adjustments, to compensate for "clustering" and "multiple testing," revealed nonsignificant differences between infection rates with N95 respirators and those with surgical face masks, reported the authors at the meeting. The reanalysis triggered a retraction of the original conclusions, which had favored the preferential use of N95 respirators. The new, nonsignificant findings are consistent with results of a recent Canadian study, which showed no added, protective benefit from N95 respirators among hospital nurses.

By advocating the more expensive N95 respirator, the originally reported Australian study had considerable cost implications. To provide a rough idea of the price differential between the 2 mask options: At labsafety.com, a 20-pack of 3M N95 respirator/surgical masks costs $24.90 ($1.25/mask), and a 50-pack of run-of-the-mill surgical masks will set you back $9.70 ($0.20/mask).