A comparison of immunotherapy schedules for injection treatment of ragweed pollen hay fever

In 44 patients highly sensitive to ragweed, we compared weekly injections of single doses of ragweed extract (RW-Wk, 15 patients) with clustered doses of ragweed extract at 3-wk intervals (RW-Cl, 18 patients) and with placebo (11 patients) for effects on ragweed hay fever symptom-medication scores and immunologic variates. Patients were matched and randomly assigned to treatment groups. Ragweed doses were advanced to the highest tolerated dose. Doses and number of visits were lower in the RW-Cl group than in the RW-Wk group. Despite lower doses, systemic reactions were not reduced and antiragweed IgE levels increased significantly more in the RW-Cl group than those in the RW-Wk group. Both the RW-Cl and RW-Wk groups had significant increases in antiragweed IgG levels, decreases in seasonal rise in antiragweed IgE levels, and lower symptom-medication scores (p < 0.01) in comparison with the placebo group. We conclude that the RW-Cl regimen offered no important advantage over RW-Wk. Seventeen patients had previously received Rinkel-method immunotherapy with 0.5 ml of end-point dilution of ragweed extract for 1 to 2 yr without significant clinical improvement or immunologic changes. After adequate treatment with either RW-Wk or RW-Cl, these patients had significantly lower symptom-medication scores than those of the placebo group and immunologic changes similar to those of the entire active-treatment group. Therefore, treatment failures on Rinkel immunotherapy respond well to adequate dose immunotherapy by either schedule.