Clinical effects of ragweed antigen emulsion: A double-blind study

Abstract

1. A double-blind study was carried out in 33 patients with ragweed pollinosis to evaluate the effects of a single injection of emulsified ragweed antigen. The group consisted of 18 patients sensitive to ragweed who were treated with emulsion antigen the previous year, and 15 patients who had never before been treated. Seventeen patients received from 1,250 to 5,000 pollen units of emulsified ragweed antigen in a single day. The remaining patients were given a placebo emulsion containing no ragweed. 2. Immediate local reactions occurred in 8 patients in the groups treated with ragweed emulsion and in one patient in the placebo group. Mild constitutional reactions occurred in 2 patients who received ragweed emulsion. 3. Clinical results were determined by assigning a daily score to each patient, based on the severity of symptoms and the amount of medication used each day. A total seasonal score for each patient and a mean seasonal score for each group of patients was calculated. While the total scores of groups treated with ragweed emulsion (both previously treated and previously untreated) were more favorable than those of the corresponding placebo-treated groups, the statistical differences between them were small and were significant at the 5 per cent level only when all antigen-treated groups were combined and compared with placebo-treated groups. 4. It is pointed out that this type of study does not allow evaluation of many variables which may influence results of treatment.