Xylitol to Prevent Acute Otitis Media

Abstract

To the Editors: We read with interest the clinical trial by Hautalahti, et al “Failure of xylitol given three times a day for preventing acute otitis media.”1 The authors report no effect on the incidence of acute otitis media (AOM) in children treated with xylitol three times daily compared with placebo, in contrast to their two previous clinical trials, which reported 20%–40% reductions in AOM among children treated with a similar total daily dose of xylitol divided five times daily.2,3 The authors explain the disparate findings on the basis of the reduced xylitol frequency, but we find a potentially more compelling explanation. In the current study, the authors’ definition of AOM as the primary outcome of interest required: (1) symptoms of “any respiratory symptoms (fever, cough, rhinitis, blocked nose, sore throat, earache, vomiting, diarrhea, nocturnal restlessness or lack of appetite)”; (2) the presence of middle ear effusion by tympanometry. This definition of AOM is imprecise in that it lacks any requirement for middle ear inflammation and would therefore misclassify episodes of otitis media with effusion (OME) as AOM.4 For example, a child with rhinitis (which could be due to a viral upper respiratory tract infection, environmental allergies, or vasomotor rhinitis) plus a serous middle ear effusion would be classified by the study as having AOM when such a child most likely has OME. Indeed, a child with diarrhea but no respiratory symptoms at all, and an incidental serous middle ear effusion would qualify as having AOM. Such nondifferential misclassification of the outcome biases towards the null and, especially since OME is much more common than AOM, could easily explain the study's null result. What makes this misclassification error all the more puzzling is that the same group of researchers used an appropriate definition of AOM in their 1998 xylitol trial, namely “The diagnosis of AOM required the finding of middle ear effusion in tympanometry (B- or C-curve), verified signs of inflammation in the tympanic membrane (emphasis added), and the presence of symptoms of acute respiratory tract infection (rhinitis, cough, conjunctivitis, sore throat, earache).”3 In summary, the trial by Hautalahti, et al demonstrates that xylitol given three times daily does not prevent OME in children. We believe that the question of whether xylitol given three times daily prevents AOM is still an open one. Louis Vernacchio, MD, MSc Allen A. Mitchell, MD Slone Epidemiology Center at Boston University Boston, MA