How to do a clinical trial? Recommendations from the aerobiological point of view

BACKGROUND: Allergy immunotherapy is still the only treatment of pollen allergy, providing a long-term effect. Clinical trials with pollen allergic patients are in need of validated, high quality pollen data and forecasts in order to grant comparability and to adhere to scientific standards. The aerobiological part of clinical trials remained hitherto not well defined, leaving the definition and use of pollen and forecast data more or less open. METHODS: Pollen data of eight Austrian pollen-monitoring stations were selected and used as an example to present a new method of pollen data replacement, in case of station failure. Gower's similarity provides an objective calculation based on a defined time frame and a specific aeroallergen (for example birch, grass, mugwort and ragweed). RESULTS: The ideal planning of the aerobiological part of a clinical trial with a pollen extract is described in detail with specific recommendations concerning site selection, pollen and forecast data, definition of the pollen season, and risk management. A checklist for every clinical trial with an aerobiological part was developed. CONCLUSION: Virtual biogeographic regions are beneficial due to their objective establishment, and can be integrated into clinical trials. Pollen data is not the same as forecast data. Both datasets have to be critically evaluated by trained aerobiologists before they are used in clinical trials. Therefore, only institutions with aerobiological knowledge, at best ISO-certified, should be involved in clinical trials and handle the aerobiological tasks.