Immediate skin test reactivity to Food and Drug Administration-approved standardized extracts

In an effort to determine whether recently introduced Food and Drug Administration-approved standardized extracts produce clinically appropriate responses in a population, 200 subjects were skin prick tested (SPT). Thirteen extracts (10 pollens, two house dust (HD) mites and cat) were tested in three groups of subjects, 50 with a history of asthma or allergic rhinitis (AL), 50 without asthma or perennial or seasonal allergic rhinitis but with a positive immediate family history for these conditions (FAL), and 100 subjects without a personal or family history for these conditions (NAL). An SPT mean wheal diameter greater than or equal to 3 mm was considered positive. Ninety percent (95% confidence interval [CI], 82% to 98%) of AL subjects had at least one positive SPT. Forty-six percent of FAL subjects (95% CI, 30% to 58%) and 29% of NAL subjects (95% CI, 20% to 38%) had at least one positive SPT. More FAL than NAL subjects had at least one SPT (p less than 0.05), and FAL subjects had more positive SPTs than NAL subjects (p less than 0.05), further supporting the genetic regulation of allergen-specific IgE production. Of the five AL subjects with no SPT wheal greater than or equal to 3 mm, three subjects were available for intradermal tests. Thirteen nonstandardized allergens similar to allergens used for SPT were applied intradermally in each of these three subjects and were all negative. Compared with history, an SPT wheal greater than or equal to 3 mm to cat produced a sensitivity of 0.90, a specificity of 0.90, and diagnostic accuracy of 0.90. Tenfold dilutions of pollens and cat reduced sensitivity without significantly improving specificity.(ABSTRACT TRUNCATED AT 250 WORDS)