Long-term benefit of allergen immunotherapy in clinical practice

Abstract

RATIONALE: Prior controlled studies have shown that allergen immunotherapy (IT) provides lasting benefit for at least three years after therapy is discontinued. Limited data is available regarding the potential enduring benefit of IT beyond five years. METHODS: We performed a retrospective survey study of patients from our practice who had completed a 3-5 year course of IT. Our clinical practice pattern is to recommend IT to motivated patients who have symptoms that are not controlled with the combination of environmental control measures and medications. We compared rhinosinusitis symptom scores prior to IT, at the completion of IT and present symptoms (0-10 visual scale). RESULTS: Cohort 1 (n=126) had completed IT 1-4 years prior (avg=2.65 yrs). The mean rhinosinusitis symptom score (RSS) before IT=8.48. Mean RSS at completion of IT=2.96. Mean RSS at present=3.97. Statistical comparisons of before IT score, at completion of IT score and at present score revealed p<0.001 for all comparisons. Cohort 2 (n=167) had completed IT 5-12 years prior (avg=7.53 yrs). The mean RSS before IT=8.26. The mean RSS at completion of IT=2.94. The mean RSS at present=3.95. Similar to cohort 1, statistical comparisons of before IT score, at completion of IT score and at present score revealed p<0.001 for all comparisons. No significant symptom score differences were apparent between cohort 1 and cohort 2. CONCLUSIONS: Our findings suggest that a 3-5 year course of IT remains effective for more than 5 years after discontinuation in most patients. Comparison of the two cohorts does not suggest diminishing benefit over time.