Study highlights dangers of latex use in the OR
September 1, 1999 3 minutes read
Study highlights dangers of latex use in the OR
Twelve percent of the anesthesia staff at Johns Hopkins University are sensitized to latex, according to study results. The findings support the need to "transform the health care environment into a latex-safe one that minimizes latex exposure to patients and hospital staff," according to Robert G. Hamilton, PhD, associate professor of medicine and pathology at the Johns Hopkins University School of Medicine in Baltimore and co-author of a study of latex allergy among Johns Hopkins staff.1
The 168 subjects who volunteered for the study comprised virtually the entire anesthesiology staff in the Johns Hopkins Department of Anesthesiology and Critical Care Medicine. The protocol included a detailed clinical history, serologic testing, puncture skin-testing, and, if required, a two-stage glove provocation test. A small number of the participants did not undergo skin testing because they were pregnant, taking antihistamines, or simply declined.
During the study, the medical and surgical staffs at Johns Hopkins were routinely using powdered natural rubber latex examination and surgical gloves.
Twenty-one (12.5%) of the subjects tested were identified as sensitized or IgE antibody-positive to natural rubber latex allergens. Of those, four (2.4%) were both sensitized and symptomatic, presenting with rhinoconjunctivitis, hives, or asthma. Hamilton told Hospital Employee Health the study is probably the most definitive prevalence study of latex allergy in a tertiary health care facility because to diagnose latex sensitization, the investigators used the most well-characterized diagnostic skin test reagent available in the United States, the Greer nonammoniated latex extract (NAL).
The Greer NAL is still pending approval by the Food and Drug Administration (FDA). The lack of an approved latex skin test reagent in the United States greatly limits diagnosis and treatment of latex allergy, laments Hamilton. The sensitivity and specificity of FDA-approved serologic techniques for detecting latex-specific IgE antibodies are not ideal, with false-negative rates as high as 25%.
Results from a multicenter investigation of latex skin-testing efficacy conducted by Hamilton and his colleagues and submitted to the FDA demonstrated that the Greer NAL "displayed an excellent diagnostic sensitivity and specificity," and that "use of the clinical history alone may lead to misdiagnosis; however, a skin test result must also be viewed within the context of the patient’s history. This is especially important in cases of asymptomatic individuals who have a positive skin test response and a confounding allergy to cross-reactive foods."1
The FDA’s sluggishness in approving a reliable latex reagent leaves this country with no skin-testing reagent to allow allergists to determine the presence of latex allergy, Hamilton says. "They cannot do their job of diagnosing latex allergy effectively and they don’t know what to do, so they’re relying solely on the patient’s history and serology results," he says.
Serology alone is not enough
"Our concern is that serological methods are not picking up all the individuals that need to be identified. On the other hand, one method gives 25% false-positive rates, and the other two, CAP and ALASTAT, have 25% false-negative rates in comparison to the Greer latex skin test. Then you are misdiagnosing cases of latex allergy, creating havoc in people’s lives and unnecessary expense," Hamilton says.
"Skin testing is critical to do it well," he continues. "It impacts workers’ compensation because it most accurately identifies allergic cases, and it impacts the management of latex allergy. If you can accurately determine who is sensitized, you can deal with those individuals more effectively. The skin-test reagent has been so slow getting through the [FDA] approval process, yet it’s so critical."
Reference
1. Brown RH, Schauble JF, Hamilton RG. Prevalence of latex allergy among anesthesiologists. Anesthesiology 1998; 89:292-299.
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