Prevention of Immunoglobulin E Sensitization to Latex in Health Care Workers After Reduction of Antigen Exposures

Abstract

To the Editor: We were very pleased to read the report by Kelly et al1 (August 2011 issue) in which they examined the reduction of sensitization to natural rubber latex (NRL) associated with changes in medical gloves. The authors are to be commended for undertaking this complex prospective investigation involving two different institutions and followed repeatedly over 4.5 years. It was no doubt difficult to complete; it is unlikely that a similar study will be conducted in the future. Most but not all earlier studies had documented the high prevalence of NRL sensitization, asthma, and other symptoms associated with NRL (for example,2–4). The declines in NRL sensitization and asthma in response to prevention interventions (substitution of glove types) have been described both at the population level and at the level of the individual.5–8 However, there were few data documenting incidence. The authors refer to our earlier incidence study conducted in Ontario, Canada.9 The strengths of the study by Kelly et al are the prospective design, the inclusion of analysis of a pre-intervention period, the comparison of changes in skin prick test positive status to negative and vice versa in both the pre-glove intervention and post-intervention periods, and the documentation of skin prick test results in duplicate with the same individual. They observed a very strong relative reduction in the rate of sensitization (16-fold) following the removal of powdered latex medical gloves. The strength of the association and the temporal (prospective) nature are obviously important Bradford-Hill criteria for causality, and this should lay to rest any doubts that powdered NRL gloves were an important exposure factor resulting in sensitization of health care workers to latex. Limitations include the low participation, the dropout over time, which is difficult to avoid in a longitudinal study, and the absence of exposure measurements after the intervention. National Institute for Occupational Safety and Health/Center for Disease Control and Prevention is to be commended for supporting and participating in the investigation. Gordon L. Sussman, MD Gary M. Liss, MD, MS University of Toronto Toronto, Ontario, Canada