Occupational asthma in symptomatic workers exposed to natural rubber latex: Evaluation of diagnostic procedures

Background: Natural rubber latex (NRL) has been increasingly identified as a cause of occupational asthma (OA). Objective: We sought to examine the accuracy of the clinical history, immun ologic tests, and assessment of nonspecific bronchial hyperresponsiveness i n diagnosing OA caused by latex compared with that of the specific inhalati on challenge (SIC). Methods: Forty-five consecutive patients referred for investigation of poss ible OA caused by latex underwent a diagnostic protocol, including an open medical questionnaire, skin prick testing against latex, measurement of bro nchial responsiveness to histamine,and inhalation challenge with latex glov es. Recorded clinical history was judged retrospectively by 4 physicians wh o mere blinded for the results of other objective tests. Results: The clinical history, skin prick testing against NRL, and assessme nt of nonspecific bronchial hyperresponsiveness showed a high sensitivity ( 87%, 100%, and 90%, respectively) but a low specificity (14%, 21%, and 7%, respectively) when compared with the results of the SIG. Logistic regressio n analysis showed that combining the results of skin prick tests against la tex with the clinical history enhanced the negative predictive value from 5 0% to 71%, whereas the positive predictive value remained virtually unchang ed (75% vs 76%). Conclusion: The clinical history and immunologic tests were the most useful procedures in diagnosing NRL-induced asthma, although combining the 2 proc edures remained less accurate than SIC. Further examination of the predicti ve values of available tests is warranted to recommend diagnostic strategie s that are specific to the various agents causing OA.