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Wise et al.

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persistent asthma was less common in patient treated with SLIT than patients receiving only pharmacotherapy. In a double-blind RCT involving 812 children with grass pollen-induced rhinoconjunctivitis, after 3 years of therapy with SQ-standardized grass pollen tablet, children in the treatment group presented a reduced risk of developing asthma compared to placebo group at 2-year follow-up (OR 0.71; p < 0.05). 1679 Although these findings are interesting, the overall strength of evidence for the prevention of asthma in SLIT studies is low at present, though the evidence for asthma symptom and medication reduction is high. Developing new allergen sensitizations frequently occurs in the natural history of respiratory allergy. Preventative effects of AIT on the onset of new sensitizations is often discussed. However, currently available SLIT data for prevention of new allergen sensitivities is also limited. The above referenced Marogna et al. 1678 study did note that the rate of new sensitizations was low, corresponding to 3.1% of SLIT-treated patients and to 34.8% of controls, with an OR of 16.85 to develop new sensitizations in controls. Another study by Marogna et al. 1680 prospectively evaluated the long-term effect of SLIT given for 3, 4, or 5 years in 78 SLIT patients vs 12 controls. Over a 15-year follow-up, all the control subjects developed new allergen sensitivities, while this occurred in less than 25% of the patients receiving SLIT (21% in treated for 3 years, 12%, in treated for 4 years, and 11% in treated for 5 years, respectively). Cost-effectiveness.: The meta-analysis comparing the efficacy and cost-savings of the 5 grass SLIT tablet vs the Timothy grass SLIT tablet has several flaws, as some trials were reported in several publications and thus these publications should be analyzed as one. More importantly, the outcome variables and the precise definition of the pollen season vary between the Timothy grass SLIT tablet and the 5-grass SLIT tablet trials, so direct comparison of outcomes should not be done, as was reviewed in detail previously. 1681,1682 The 5-grass SLIT tablet ($1003 Canadian dollar) was associated with cost savings against year-round SCIT (+$2471), seasonal SCIT (+$948), and the Timothy grass SLIT tablet (+ $1168) during the first year of therapy and still during the second and third year of treatment. The higher costs for SCIT were due to the elevated indirect costs from missing working hours and transportation costs due to in-office SCIT administration. The higher costs for the Timothy grass SLIT tablet were due to the year-round dosing vs the preseasonal/co-seasonal 6-month total dosing of 5-grass SLIT tablet. A UK meta-analysis of costs showed that SCIT and SLIT may be cost-effective compared with standard pharmacotherapy for 6 years (when considering a threshold of pound 20,000-30,000 per quality-adjusted life-year [QALY]). The investigators were not able to establish a clear difference between SCIT and SLIT in cost-effectiveness. 1617 Additional data from double-blind placebo-controlled trials.: Some of the most important recent trials with data that add to the already presented systematic reviews are listed here: • High-dose tree pollen aqueous SLIT was effective in reducing symptom medication scores in children in a high-quality double-blind placebo-controlled trial. 1683

Author Manuscript Author Manuscript Author Manuscript Author Manuscript

Int Forum Allergy Rhinol . Author manuscript; available in PMC 2020 June 10.