- A documented, positive skin test to an appropriate perennial allergen (animal dander, house dust mites, cockroaches and/or mold) or documented, historical, in vitro test results for a specific IgE (such as RAST, PRIST) within the past 12 months prior to Visit 1 will be allowed. A positive skin test during Visit 1 will also be allowed. A positive skin test is defined as a wheal 3mm larger than the diluent control for prick testing.