Allergic skin tests and respiratory diseases in 1612 subjects

In 1985-90, 1612 subjects were submitted to allergic tests for respiratory diseases. In a retrospective survey we have evaluated clinical features, symptoms, diagnostic procedure and allergic tests of skin positives and skin negatives. Prick tests were supplemented by intradermal reaction and RAST under guideline of history. Allergens examined were Gramineae, Parietaria, Olea, house dust, Dermatophagoides farinae and pteronyssinus. 80% of patients were found positive to one or more allergens; their average age (30.1 +/- 13.7) was found lower (p < 0.001) and allergic family history prevalence higher (p < 0.01) than skin negatives. Skin positives prevalence was statistically significant under 50 yrs and skin negatives one over 50 yrs. Asthma or rhinitis only were prevalent among skin negatives while associated symptoms (asthma + rhinitis and/or conjunctivitis) were prevalent among skin positives. Considering skin results pollens were found positive in 34%, inhalants in 24% and pollens + inhalants in 42% of subjects. Gramineae were found positive in 57.8% of subjects, Parietaria in 39.8%, olea in 28.8%, Dermatophagoides farinae in 53.3%, house dust in 52.1% and Dermatophagoides pteronyssinus in 48.2%. Prick test showed a high sensitiveness in detecting pollens sensitization while intradermal reactions were often necessary in sensitization to inhalants; for the diagnosis RAST contribution was negligible.