Medication persistence with long-term, specific grass pollen immunotherapy measured by prescription renewal rates.

Objective: We assessed medication persistence using prescription renewal rates for grass pollen specific immunotherapy (SIT) in a representative population of patients in Germany to evaluate whether the perception of superior persistence for the subcutaneous route compared to the sublingual route could be confirmed in clinical practice.

Methods: Individual prescriptions for allergen immunotherapy were extracted from a national prescription database (INSIGHT Health) and followed over 3 years on a per-patient basis. However, patients' medical history and treatment schedules were not available for analysis. Products were identified by the national drug code (PZN number) and grouped to either subcutaneous immunotherapy (SCIT) with natural extract injections, SCIT with modified allergens (allergoids) or sublingual immunotherapy (SLIT) with natural pollen extract solutions. Persistence was defined as at least one prescription of the individual drug in the respective years.

Results: A total of 1409 patients started SIT in 2005 (112, 695, and 602 for natural extract SLIT, natural extract SCIT, and allergoid SCIT, respectively). In 2006, 71%, 55%, and 59% of those patients had at least one renewal prescription of natural extract SLIT, natural extract SCIT, and allergoid SCIT, respectively, as well as 51%, 34%, and 39% in 2007. In both years, persistence with natural extract SLIT was significantly higher than with natural extract SCIT (p = 0.0015 for 2006, p = 0.0003 for 2007) and allergoid SCIT (p = 0.0152 for 2006, p = 0.0111 for 2007). There were no significant differences between the two SCIT groups.

Conclusion: Medication persistence with grass pollen SIT in a representative sample of patients in Germany was similar to published medication persistence in asthma and COPD patients. The sublingual application route shows significantly better persistency than the subcutaneous route with native allergens or allergoids.