David H. Garabrant, H. Daniel Roth, Romain Parsad, Gui-Shuang Ying and Jay Weiss

This paper analyzes national health data obtained in the Third National Health and Nutrition Examination Survey (NHANES III). This survey of more than 30,000 people is conducted every six years by the National Center for Health Statistics. Participation included a lengthy questionnaire and a physical examination in a mobile examination center. Data generated by the NHANES studies are viewed by epidemiologists as among the most reliable epidemiological data available. Numerous epidemiological papers have been published over the years based upon data generated from the NHANES surveys.

Dr. Garabrant and his colleagues used data collected from 5,512 adults aged 17-60 years. Using both simple and complex epidemiological models, the investigators sought to determine the factors associated with latex sensitization and, in particular, whether or not working in the healthcare environment increased one's risk for developing latex sensitization.

Dr. Garabrant found that once demographic factors, such as age, sex, race and atopy were controlled, there was no association between healthcare worker status and use of protective gloves with latex sensitization. This risk among such workers was no different than that among workers in 39 other occupations in which use of latex gloves was uncommon.

Dr. Garabrant also looked to see if there was an association between people who listed healthcare work as their longest held occupation compared to 39 other occupations that were coded in the survey. Unfortunately, the NHANES survey did not ask whether protective gloves were used in connection with the longest held occupation. Among those listing healthcare work as their longest held occupation, there was a non-statistically significant association between longest held jobs in the healthcare field and latex sensitization (odds ratio = 1.49, 95% confidence interval (CI): 0.92, 2.40).

Dr. Garabrant and his researchers confirmed results reported by others that the strongest risk factor for latex sensitization among healthcare workers is a history of atopy. Dr. Garabrant's finding that use of protective gloves while working in the healthcare field was not a risk factor for natural rubber latex (NRL) sensitization is consistent with data generated by the National Institute of Occupational Health and Safety (NIOSH). While performing a health hazard evaluation of more than 500 healthcare workers at St. Joseph's Hospital in Denver, NIOSH failed to find that healthcare workers who use NRL gloves had a higher risk of NRL sensitization than healthcare workers at that same hospital that did not use NRL gloves.

The editors of the American Journal of Epidemiology invited commentary on Dr. Garabrant's article from Drs. Daniel Wartenberg and Gail Buckler. Drs. Wartenberg and Buckler argue that Dr. Garabrant's analysis has to be viewed cautiously in light of the questionable specificity of the assay (AlaSTAT EIA) that was chosen by the Centers for Disease Control and Prevention (CDC) to test for latex sensitization in NHANES III. They suggest that the results reported by Dr. Garabrant are the result of reporting bias and/or a healthy worker effect.

In their reply, Dr. Garabrant and his researchers respond that the studies cited by Drs. Wartenberg and Buckler for their assertion that the AlaSTAT EIA assay has a relatively low specificity are relevant for diagnosing NRL allergy, not latex sensitization. As noted by Dr. Garabrant and his researchers, the CDC did not use the AlaSTAT EIA assay to diagnose NRL allergy. Rather, the CDC used the assay only to determine whether a subject was NRL sensitized. When used for the limited purpose of determining the presence of NRL sensitization, the AlaSTAT EIA has an extremely high specificity of 91.1% at the 0.35 IU/mL criteria for positivity and 98.4% specificity at the 1.50 IU/mL criteria for positivity. Thus, Dr. Garabrant argues that their results cannot be minimized by an alleged low specificity of the assay. Second, Dr. Garabrant points out that 74% of the subjects aged 17-60 reported having a current occupation, while only 3% did not provide a response regarding a current occupation. Of those who reported having a current occupation, 96% provided information on use of protective equipment, and all but 0.4% of those provided information on glove use. Thus, the percentage of people responding to the questions on current occupation and use of protective equipment does not suggest that reporting bias can explain the results. Furthermore, no data suggests that there were significant departures from the healthcare field from 1988-1991 as a result of NRL sensitization that could give rise to a concern about a healthy worker effect. This issue was actually studied by NIOSH in its health hazard evaluation at St. Joseph's Hospital in 1997. Despite the much greater public awareness of NRL sensitization and NRL allergy, NIOSH was unable to find any evidence of the healthy worker effect to explain the lack of any association between NRL sensitization and glove use among healthcare workers.

The publication of Dr. Garabrant and his researchers' comprehensive analysis in one of the country's premier epidemiological journals adds significantly to the current debate regarding the role of NRL gloves in causing NRL sensitization and/or allergy among healthcare workers. However, this study, like any other study by itself, does not resolve these questions. The data, however, are consistent with the repeated failure of investigators over the past ten years to find any dose response association between the use of NRL gloves and the risk of NRL sensitization among healthcare workers.

*Article published in American Journal of Epidemiology, Vol. 153, No. 6, March 15, 2001.