RISK OF INSECT STING ANAPHYLAXIS AFTER DISCONTINUING VENOM IMMUNOTHERAPY

毒液免疫疗法降低了对昆虫叮咬的全身过敏反应的风险，从治疗前观察到的50%水平降低到维持治疗时的2%以下。当治疗在5年或更长时间后停止时，我们以前曾报道过，在停止治疗后的最初几年内，刺痛反应的风险仍然低于10%。一些研究者研究了仅3年后停止治疗，但建议限制，如年轻患者，反应较轻，治疗期间针刺激发阴性或RAST阴性。在停止治疗的前三年，我们的结果显示，毒液皮肤试验和IgE患者对刺激性叮咬确实有全身反应，但症状轻微甚至轻微。大多数关于停止毒液免疫疗法的研究都只报道了停止后一两年的结果。目前尚未报告停止治疗患者的长期结局。我们假设，在5年后停止治疗的患者中，随着时间的推移，敏感性的消失几乎没有反应的风险。然而，最近的报告表明，风险可能持续存在，治疗前反应的严重程度可能是反应风险的决定因素。已经合理地假设，如果毒液皮肤试验或RAST变为阴性，则可以停止治疗，这发生在少数患者中。然而，皮肤测试对Hypletera毒液的敏感性水平，最好的可用指标，与对蜇伤的临床反应的严重程度无关，并且没有发现比历史和皮肤测试预测的平均50%风险更准确地预测蜇伤结果的标志物。这项研究的结果将显示患者是否可以在3年后安全停止治疗，而不是我们目前建议的5-6年，以及在停止治疗后的10年内反应风险是否仍然可以接受。我们还将确定治疗前反应史不太严重的患者或皮肤试验和/或RAST阴性的患者是否风险较低。迄今为止，我们已经回顾了236例患者，其中32例在1998年赛季完成了刺击挑战（另有7例在1997年完成了刺击）。未发生全身反应。在1999年的季节里，已经联系了更多的病人进行刺击。我们还在为可能喜欢或需要终身维持VIT的患者寻求更安全的替代方案，以停止VIT。我们已经开始研究延长12-16周的维持间隔，这可以减少患者的不便和这种治疗的长期成本。

Venom immunotherapy reduces the risk of a systemic allergic reaction to an insect sting from the 50% level observed before treatment to less than 2% on maintenance therapy. When therapy is discontinued after 5 years or more, we have previously reported that the risk of a sting reaction remains less than 10% in the first few years after stopping treatment. Some investigators have studied discontinuation of therapy after only 3 years, but have suggested restrictions such as younger patients, milder reactions, negative sting challenge during therapy or negative RAST. In the first three years off therapy, our results showed that the venom skin test and IgE patients who did have systemic reactions to challenge stings had mild or even trivial symptoms. Most of the studies of discontinuing venom immunotherapy have reported the outcome of stings only in the first year or two after stopping. There are no reports of the long-term outcome in patients who remain off treatment. We hypothesized that there would become almost no risk of reaction with the disappearance of sensitivity over time in patients who stop treatment after 5 years. However, recent reports suggest that the risk may persist and that the severity of the pre-treatment reaction may be a determinant of the risk of reaction. It has been reasonably assumed that treatment can be stopped if the venom skin teat or RAST becomes negative, which occurs in a minority of patients. However, the level of skin test sensitivity to Hymenoptera venom, the best available indicator, does not correlate with the severity of the clinical reaction to a sting and no markers have been found to predict the outcome of a sting any more accurately than the average 50% risk predicted by history and skin test. The results of this study will show whether patients can safely stop after only 3 years instead of our current recommendation of 5-6 years, and whether the risk of reaction remains acceptably low in the 10 years after stopping therapy. We will also determine whether there is a lower risk in those patients with a less severe history of reaction before treatment or in those who have developed negative skin tests and/or RAST. We have reviewed 236 pateints to date, of whom 32 compeleted sting challenge during the 1998 season (another 7 were previously stung in 1997). No systemic reactions have occurred. Additional patients have been contacted for sting challenge in the 1999 season. We are also seeking safer alternatives to discontinuing VIT for patients who may prefer or require maintenance VIT for life. We have begun studies of prolonged maintenance intervals of 12-16 weeks which could reduce the inconvenience to the patients and the long-term costs of this therapy.