Assessment of specific immunotherapy efficacy using a novel placebo score-based method.

BACKGROUND: In trials of allergen immunotherapy, allergen exposure is typically assessed by pollen counts, but these may misrepresent exposure if performed remotely from multiple study centers. OBJECTIVE: To assess whether symptomatology in placebo-treated patients is a better measure of local allergen burden at individual centers in such trials. METHODS: Data from a multicenter, placebo-controlled trial of preseasonal grass pollen immunotherapy were reanalyzed to identify the 4 weeks at each center in which the placebo-treated subjects had the highest combined symptom/medication scores (CSMS). The difference in CSMS between active and placebo groups was compared during the 4 peak placebo score weeks (PlSW) and the 4 peak pollen count weeks (PoCW). RESULTS: The benefit of immunotherapy over placebo in the PlSW analysis (18.5%) was greater than in the PoCW analysis (13.6%), with increased statistical significance (P = .0001, .0038, respectively). Similar improved discrimination was observed when analyzing benefits in subgroups of patients with severe symptoms, a high disease burden, and in different geographical locations. CONCLUSION: This novel PlSW analysis results in better discrimination of the effects of allergen immunotherapy compared with placebo and may be widely applicable in similar studies, both prospectively and retrospectively.

The effect of desloratadine on eosinophil/basophil progenitors and other inflammatory markers in seasonal allergic rhinitis: a placebo-controlled randomized study.

BACKGROUND: Eosinophil/basophil (Eo/B) progenitors fluctuate in the peripheral circulation during seasonal allergen exposure in atopic subjects. Several drugs have been shown to modulate Eo/B progenitor levels in the peripheral blood but, to date, the possible effect of antihistamines on Eo/B progenitors has not been explored. Our objective was to evaluate whether the antihistamine desloratadine (DL) can modulate peripheral blood Eo/B progenitors or other markers of allergic inflammation. METHODS: We performed a randomized double-blind placebo-controlled study on the effects of DL on peripheral blood Eo/B progenitors in subjects with symptomatic, seasonal allergic rhinitis during a ragweed pollen season. Forty-five subjects were randomized to treatment for 4 weeks with DL 20 mg daily or placebo. RESULTS: The expected fall in the number of Eo/B progenitors from baseline to 2 weeks of treatment was seen in the placebo group [median drop of 1.0 colony-forming unit (CFU)/10(6) cells], and was greater than in the DL group (median drop of 0.0 CFU/10(6) cells) (p = 0.013). The change in histamine concentration per colony from baseline to 2 weeks of treatment was lower in the DL group (median decrease of 6.1 pg/colony) compared to placebo (median increase of 1.8 pg/colony) (p = 0.01). An increase in the nasal lavage eotaxin concentration from baseline to 4 weeks of treatment was statistically significant in the placebo group but not in the DL group. Eo/B CFU were not affected by varying in vitro concentrations of DL. CONCLUSION: These results suggest that DL can modulate aspects of allergic inflammation in vivo through mechanisms other than simple blockade of H1 histamine receptors.