Percentage of asthma cases attributable to atopy based on number of positive skin prick tests and specific skin prick tests
| Skin prick tests2-150 | % Non asthmatics atopic (n =399) | % Asthmatics atopic (n =315) | Relative risk | % of cases attributable to atopy |
|---|---|---|---|---|
| No. of positive tests | ||||
| 1+ | 35.1 | 57.1 | 2.5 | 34 |
| 2+ | 16.5 | 40.6 | 3.5 | 29 |
| 3+ | 7.3 | 27.3 | 4.8 | 22 |
| 4+ | 2.0 | 14.3 | 8.1 | 13 |
| 5+ | 1.0 | 9.8 | 10.8 | 9 |
| 6+ | 0.5 | 7.0 | 14.9 | 7 |
| 7+ | 0.3 | 2.9 | 11.7 | 3 |
| Specific skin prick tests | ||||
| Any positive test | 35.1 | 57.1 | 2.5 | 34 |
| Rye grass | 23.4 | 44.4 | 2.6 | 27 |
| House dust mite | 19.4 | 43.7 | 3.2 | 30 |
| Cat | 5.5 | 23.2 | 5.2 | 19 |
| Alternaria | 4.5 | 8.6 | 2.0 | 4 |
| Dog | 2.2 | 9.9 | 4.9 | 8 |
| Horse | 1.8 | 10.2 | 6.3 | 9 |
| Cladosporium | 1.3 | 5.7 | 4.7 | 4 |
| Kapok | 1.5 | 4.1 | 2.8 | 3 |
| Aspergillus fumigatus | 0.5 | 4.8 | 9.7 | 4 |
| Wool | 0.8 | 4.4 | 6.0 | 4 |
| Penicillium | 2.0 | 2.5 | 1.3 | 1 |
↵2-150 Defined as the development of weals at least 2 mm greater than negative control.
Adapted from Sears et al.22