BACKGROUND: In the absence of direct comparisons, indirect treatment comparisons (ITCs) of symptom and medication score endpoints are valuable for comparing clinical efficacy between 2 different sublingual immunotherapy (SLIT) tablets used to treat grass pollen–induced allergic rhinitis: 5-grass pollen vs. 1-grass pollen SLIT tablet.
METHOD: Electronic medical literature databases, conference and health technology assessment websites, and trial registries were systematically reviewed for articles that reported comparable endpoints for 5-grass or 1-grass pollen SLIT tablets. After article screening and quality assessment, endpoints of eligible studies were analyzed using frequentist Bucher-adjusted ITCs. Primary analyses included all patient ages for short-term endpoints and only adults for long-term endpoints (≥1 year after treatment discontinuation). Analyses of short-term outcomes were additionally performed for an adults-only subgroup and a children-and-adolescents subgroup. Analyses were based on standardized mean differences (SMDs) to adjust for differences in scoring systems used for symptom and medication scores. Each score was analyzed independently as a continuous outcome and evaluated as the average of daily scores gathered over an entire grass pollen season.
RESULTS: 13 articles on randomized controlled trials (5-grass pollen SLIT tablet, n=5; 1- grass pollen SLIT tablet, n=8) were included. Primary ITCs demonstrated no statistically significant differences between 5-grass and 1-grass pollen SLIT tablets in short-term effects on symptom (SMD, −0.0176; 95% confidence interval [CI], −0.1697 to 0.1346) and medication scores (SMD, −0.0519; 95% CI, −0.1887 to 0.0848) (Table 1). ITCs of adult patients showed no significant differences in symptom (SMD, 0.2292; 95% CI, −0.1080 to 0.5664) and medication scores (SMD, 0.0605; 95% CI, −0.2758 to 0.3967) between 5-grass and 1-grass pollen SLIT tablets over the long term. Similarly, the results of subgroup analyses of studies recruiting adult patients only and of studies recruiting children and adolescents were broadly consistent with the primary analysis results (Table 1).
CONCLUSION: These findings of ITCs of children, adolescents, and adults with grass pollen– induced allergic rhinitis suggest no statistically significant differences between symptom and medication scores for 5-grass and 1-grass pollen SLIT tablets.
