Jewett D L, Fein G, Greenberg M H
Department of Orthopaedic Surgery, School of Medicine, University of California, San Francisco 94143-0728.
N Engl J Med. 1990 Aug 16;323(7):429-33. doi: 10.1056/NEJM199008163230701.
Some claim that food sensitivities can best be identified by intradermal injection of extracts of the suspected allergens to reproduce the associated symptoms. A different dose of an offending allergen is thought to "neutralize" the reaction.
To assess the validity of symptom provocation, we performed a double-blind study that was carried out in the offices of seven physicians who were proponents of this technique and experienced in its use. Eighteen patients were tested in 20 sessions (two patients were tested twice) by the same technician, using the same extracts (at the same dilutions with the same saline diluent) as those previously thought to provoke symptoms during unblinded testing. At each session three injections of extract and nine of diluent were given in random sequence. The symptoms evaluated included nasal stuffiness, dry mouth, nausea, fatigue, headache, and feelings of disorientation or depression. No patient had a history of asthma or anaphylaxis.
The responses of the patients to the active and control injections were indistinguishable, as was the incidence of positive responses: 27 percent of the active injections (16 of 60) were judged by the patients to be the active substance, as were 24 percent of the control injections (44 of 180). Neutralizing doses given by some of the physicians to treat the symptoms after a response were equally efficacious whether the injection was of the suspected allergen or saline. The rate of judging injections as active remained relatively constant within the experimental sessions, with no major change in the response rate due to neutralization or habituation.
When the provocation of symptoms to identify food sensitivities is evaluated under double-blind conditions, this type of testing, as well as the treatments based on "neutralizing" such reactions, appears to lack scientific validity. The frequency of positive responses to the injected extracts appears to be the result of suggestion and chance.
一些人声称，通过皮内注射疑似过敏原提取物来重现相关症状，能够最好地识别食物过敏。人们认为，不同剂量的致病过敏原可“中和”这种反应。
为评估症状激发试验的有效性，我们进行了一项双盲研究，该研究在七位支持并熟练使用此技术的医生的办公室中开展。同一名技术人员使用与之前在非盲法试验中认为会引发症状的相同提取物（相同稀释度、相同生理盐水稀释剂），对18名患者进行了20次测试（两名患者测试了两次）。每次测试时，随机依次注射三次提取物和九次稀释剂。评估的症状包括鼻塞、口干、恶心、疲劳、头痛以及定向障碍或抑郁感。所有患者均无哮喘或过敏反应病史。
患者对活性注射剂和对照注射剂的反应无法区分，阳性反应的发生率也是如此：27%的活性注射剂（60次中的16次）被患者判定为活性物质，对照注射剂的这一比例为24%（180次中的44次）。一些医生在患者出现反应后给予的用于治疗症状的中和剂量，无论注射的是疑似过敏原还是生理盐水，效果均相同。在实验过程中，将注射剂判定为活性的比例保持相对稳定，因中和或习惯化导致的反应率没有重大变化。
在双盲条件下评估用于识别食物过敏的症状激发试验时，此类测试以及基于“中和”此类反应的治疗方法似乎缺乏科学依据。对注射提取物的阳性反应频率似乎是暗示和偶然的结果。
