Correspondence: prevalence of latex allergy.
Ann Allergy, Asthma, & Immun 2001 Aug; 87(2):164
I am writing in response to Dr. Yeang's article "Prevalence of latex allergy may be vastly overestimated when determined by in vitro assays." Positive predictive value (PPV) is dependent on both test specificity and the prevalence of the condition in the population. As prevalence declines, so does the PPV; therefore, the author is correct in stating that the prevalence may be overestimated when the true prevalence is low. Alternatively, imperfect sensitivity leads to underestimates of prevalence. However, this is also true when determining the prevalence by skin prick testing (SPT). 8PT is not 100% sensitive and specific. SPTs can be falsely negative or positive. The Allergy Report states that some patients who have a strong history of systemic reactions may have negative skin tests for IgE to suspected allergens clinical symptoms strongly suggestive of latex allergy can often not be confirmed with SPT. Up to 60% of positive SPTs to foods and up to 50% of positive SPTs to latex do not reflect symptomatic allergy. There is no gold standard for the diagnosis of allergy; the closest thing is probably challenge testing. However, sensitivity and specificity of available diagnostic testing Methods are determined by comparison to clinical history in the case of SPT or clinical history and/or SPT in the case of serologic testing. This has led to reporting of a wide variety of sensitivities and specificities of both SPT and in vitro testing. My review of the literature on the prevalence of latex sensitization has not revealed major differences between studies using SPT or in vitro tests. A wide range of prevalence rates are reported for both methods. Rates in healthcare workers range from 2.9% to 22 % when determined by SPT and 2.9% to 12% when determined by in vitro methods. Rates in persons without occupational exposure to latex have rates ranging from 0.12% to 9% when determined by SPT, and 2% to 12% when using in vitro testing. In conclusion, it is clear that both SPT and in vitro tests have less than perfect sensitivity and specificity. However, exclusive emphasis on specificity without regard for sensitivity adds little to further understanding of the prevalence of latex allergy.
Allergens; Allergic-reactions; Allergies; Immune-reaction; Humans
Annals of Allergy, Asthma, and Immunology