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.