Grass pollen symptoms interfere with the recollection of birch pollen symptoms - a prospective study of suspected, asymptomatic skin sensitization.

ABSTRACT

BACKGROUND: Asymptomatic skin sensitization (AS) is a risk factor for the development of allergic symptoms. A meticulous definition of this condition requires a systematic assessment of clinical symptoms before inclusion. OBJECTIVE: To examine the concordance between retrospective assessment of seasonal allergic symptoms and prospective seasonal symptom registration among subjects with AS. METHODS: On the basis of a population survey, autumn 2002, including skin prick tests (positive if > or =3 mm) and a screening questionnaire, 87 subjects with AS to birch and/or grass pollen, birch and/or grass pollen allergic symptomatic subjects (n = 63) and healthy controls (n = 40) were included in January to March 2003, completed diary cards on symptom and medication use during the relevant seasons 2003, and were examined at follow up in autumn 2003. Allergy positive SPT and symptoms > or = seven diary days. RESULTS: Eleven AS subjects (birch n = 10) subsequently developed allergic symptoms, yet nine admitted, at follow up, to have had symptoms before inclusion, or even denied pollen-related symptoms despite a significant diary. Compared with AS subjects sensitized to grass pollen, AS subjects sensitized to birch pollen had significantly larger skin prick reactions and more often and severe pollen symptoms. CONCLUSION: In the context of double-sensitization, retrospective symptom assessment is not a reliable method for ensuring that subjects classified, as asymptomatically skin sensitized, are truly, asymptomatic. This matter should be considered in studies on allergy development.