INCIDENCE AND RISK-FACTORS FOR LATENT SENSITIZATION TO CHYMOPAPAIN - PREDICTIVE SKIN-PRICK TESTS IN 700 CANDIDATES FOR CHEMONUCLEOLYSIS

Seven hundred patients were investigated prospectively before undergoi ng chemonucleolysis. A past history of allergy and/or previous exposur e to papain, either in food, beverages or drugs, was sought, and a ski n-prick test with chymopapain was performed. Based on the results obta ined, the subjects were classified into four groups: Group I-225 non-a topic non-papain-exposed subjects; Group II-285 non-atopic papain-expo sed subjects; Group III-69 atopic non-papain-exposed subjects; and Gro up IV-121 atopic papain-exposed subjects. Latent sensitization to papa in was observed in 0.4% of subjects in Group I, 3.16% in Group II, 5.8 % in Group III and 7.4% in Group IV. The odds ratios were 13.8 for ato py and 7.3 for exposure to papain. Interaction between atopy and papai n exposure did not result in a significantly greater risk. Neither sex nor age nor a history of a previous drug reaction were risk factors. Only one patient out of the 23 who were sensitive to papain had no ris k factor. The 677 skin-test negative patients then underwent chemonucl eolysis and none of them had an anaphylactic reaction. This was signif icantly less frequent: (P=0.04) than the incidence in a random populat ion (0.45%). Prick tests performed 6 weeks and 6 months after chemonuc leolysis revealed newly acquired sensitization in 36% of the patients. Atopy was not a risk factor for this event. Three points are discusse d: (i) the negative predictive value of skin-prick tests with chymopap ain is confirmed; (ii) subjects likely to be sensitized are atopic and /or have been exposed previously to food or drugs containing papain an d therefore they can be identified pre-operatively by a questionnaire; (iii) atopy is a risk factor for the induction of specific IgE to all ergens internalized via a mucosal surface but not for those that are i njected parenterally.