Sublingual grass allergen specific immunotherapy : a retrospective study of clinical outcome and discontinuation

Background: Sublingual immunotherapy (SLIT) is effective, tolerable, and convenient for many allergic patients. Still, real-world evidence is scarce and the aim of this study is to assess the patient reported outcome of treatment with SLIT against grass pollen allergy in a consecutive patient population. Methods: Patients (n = 329) who were confirmed to be allergic to timothy grass and had been prescribed SLIT were consecutively enrolled in the study and completed a questionnaire online or in hard copy. Results: 207 (62.9%) patients responded to the questionnaire. The female/male ratio was 105/102 with a mean age of 39 ± 11 years (range 19-70 years). 113 (55%) patients reported they had completed the full 3-year treatment period, 49 (24%) were still on treatment, and 45 (22%) had discontinued treatment prematurely. Respondents who had completed the full treatment period reported that their allergy symptoms in the most recent grass pollen season had improved to a larger extent than subjects still on treatment or discontinuing the treatment prematurely. Improvement of asthma was twice as common among patients who completed compared to discontinued treatment (42 vs. 20%). Younger age (37 ± 12 vs. 41 ± 11 years, p < 0.001) and a higher prevalence of reported oral and/or gastrointestinal side effects (49 vs. 24%, p = 0.02) characterised the group that terminated SLIT. Forgetfulness was the most commonly reported specific reason. Conclusion: Treatment perseverance resulted in improved patient reported outcome. Forgetfulness was the most frequently reported reason for discontinuing SLIT treatment against grass pollen allergy