Antihistamines modestly reduce side effects of peanut oral immunotherapy
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The use of H1 or H2 antihistamines may mitigate some side effects of peanut oral immunotherapy, but they did not influence quality of life, according to a study published in The Journal of Allergy and Clinical Immunology: In Practice.
Future trials should explore safer approaches to food allergy treatment that improve quality of life, Derek K. Chu, MD, PhD, of the department of medicine at McMaster University in Hamilton, Ontario, Canada, and colleagues wrote.
The randomized, three-arm, parallel-design, placebo-controlled Peanut Immunotherapy Starting in Canada, Evaluation and DiScovery, or PISCES, trial involved 43 patients (mean age, 7.8 years; age range, 5 to 11 years; 65% boys) with peanut allergy being treated with OIT at Hamilton Health Sciences’ McMaster Children’s Hospital.
Researchers assigned 10 patients to “double placebo” with placebo OIT and placebo premedication, 16 to peanut OIT with placebo premedication and 17 to peanut OIT with antihistamine premedication.
The patients assigned to antihistamine premedication before their OIT received 2.5 mg of desloratadine, a second-generation H1 antihistamine, in 5 ml by mouth once a day or 75 mg of ranitidine, an H2 blocker, in 5 ml by mouth twice a day.
The risk for experiencing at least one adverse event was higher among those treated with OIT vs. the double-placebo group, whether they received OIT with antihistamines (HR = 3.75; 95% CI, 2.79-4.72) or with placebo (HR = 4.62; 95% CI, 3.61-5.62).
However, premedication with antihistamines before peanut OIT reduced the number of moderate or severe adverse events compared with OIT without antihistamines (1.9 vs. 4.2 events per patient; incidence rate ratio [IRR] = 0.46; 95% CI, 0.24-0.89).
Still, both OIT groups saw increases in their rates of moderate or severe adverse events compared with the double-placebo group at 0.9 events each (OIT without antihistamines, IRR = 4.65; 95% CI, 2.02-10.73; OIT with antihistamines, IRR = 2.16; 95% CI, 1.01-4.6).
According to the researchers, reductions in urticaria drove these differences, with fewer events per patient on peanut OIT with antihistamines (0.6 vs. 2.1; IRR = 0.28; 95% CI, 0.1-0.8) and on double placebo (0.7 vs. 2.1; IRR = 3.04; 95% CI, 1.17-7.88) compared with patients on peanut OIT without antihistamines.
The participants on peanut OIT with antihistamines experienced numerically, but not significantly, fewer abdominal pain events than those on OIT without antihistamines (2.6 vs. 4.6; IRR = 0.61; 95% CI; 0.27-1.37), with both OIT groups experiencing more events than the 0.8 observed in the double-placebo group.
Additionally, the antihistamine premedication increased incidence of neuropsychiatric events, primarily tiredness and dizziness, compared with placebo premedication (3.35 vs. 1.06; IRR = 3.16; 95% CI, 1.84-5.42).
After 12 months, mean quality-of-life scores were 4.36 (standard deviation [SD], 1.1) for the participants on peanut OIT and antihistamines, 3.28 (SD, 0.99) for those on peanut OIT and a placebo, and 3.63 (SD, 0.62) for those in the double-placebo group, which suggested small or no differences between the groups. Reviews of specific scores pertaining to emotional impact, food anxiety and social and dietary limitations yielded similar results.
These results suggest that adverse events caused by OIT are not the only factors impacting quality of life, the researchers wrote. Also, they continued, antihistamines do not have enough of an impact on adverse events to significantly improve quality of life.
Although antihistamines do not increase the costs of oral immunotherapy, their addition to an already complex regimen should be weighed against their modest benefits and their potential for adverse effects, according to the researchers.
Future research should investigate safer food allergy treatment approaches that improve patient and family quality of life, the researchers concluded, noting that the OUtMATCH study will explore the use of omalizumab (Xolair; Genentech, Novartis) with peanut oral immunotherapy.
Perspective
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These results are not too surprising. However, I have not used antihistamines as part of an OIT treatment protocol, as I have not wanted it to become a “crutch” or mask symptoms. Ultimately, we want patients to consume foods and doses safely without the need of other medications. I have used antihistamines in conjunction with OIT for other reasons such as environmental allergies or eczema, but they were used for that purpose and not OIT.
One interesting finding in the study was that concurrent treatment with antihistamines reduced moderate to severe but not mild OIT-induced adverse events, and yet it did not lead to important improvements in quality of life. Further, there were additional adverse effects such as sedation and dizziness in the antihistamine group.
Overall, it does not seem that adding antihistamines moved the needle much. I also think the quality-of-life assessments and conclusions were not thorough. First, there was no indication of what quality-of-life measures were accounted for. Second, they only did a baseline assessment and then another assessment 4 weeks after the desensitization. This does not allow much time for the participants to really understand the difference that OIT may have made. Third, the maximum doses achieved in this study imply that the patient would not have been allowed to free-eat foods after OIT. If this is the case, then that would likely affect quality-of-life scores. So, I think these aspects should be more carefully evaluated before drawing conclusions.
I think this study shows that OIT can be performed without antihistamines and that they are not needed as part of a protocol. Rather, they can be used to control concurrent allergic disorders such as environmental allergies or eczema.
Further research is needed into quality-of-life assessments with varying maintenance doses of OIT and after patients have been in maintenance for a longer period and incorporating foods more regularly into their diets. Also, as the article suggests, similar research with biologics may show different results as well.
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