RT Journal Article SR Electronic T1 Clinical relevance of positive skin prick test to house dust mite in Portugal and Finland JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP P891 VO 42 IS Suppl 57 A1 Diana Silva A1 Osmo Kari A1 Mariana Couto A1 Sirje Peltonen A1 Juho Wares A1 Leena Petman A1 Luis Delgado A1 André Moreira A1 Tari Haahtela YR 2013 UL http://erj.ersjournals.com/content/42/Suppl_57/P891.abstract AB Prevalence of positive skin prick test (SPT) to house dust mite Dermatohagoides pteronyssinus(Dp) in subjects sent to allergy testing owing to symptoms range from 81% in Portugal to 37% in Finland. Due to climatic differences, indoor Dp is readily found in Portugal but not in Finland. We compared the clinical relevance of positive SPT to Dp in Porto and Helsinki. A total of 130 patients (75 Porto, 55 Helsinki) participated; 81 with respiratory symptoms, ≥8 years, referred to Hospital São João, Porto or Skin and Allergy Hospital, Helsinki, were included if they had a positive SPT (wheal≥3 mm) to Dp (LETI). Half (n=41) were monosensitized to Dp while the others were polysensitized. 49 patients with negative SPT to Dp were included as controls. After informed consent a double blind placebo controlled conjunctival challenge (CC) with Dp was performed (LETI). Diagnosis of asthma, rhinitis or conjunctivitis was set after medical consultation. Conjunctival challenge to Dp showed a sensitivity of 88% and specificity of 96% in terms of concordance of the SPT and CC results. A wheal size greater than 4.8mm in Porto and 3.5mm in Helsinki predicted a positive CC (Porto, AUC=0.986; Helsinki, AUC=0.963). Two patients in the control group showed a positive CC. In Porto the patients with positive CC to Dp had an increased risk for asthma (OR 9.3, 95%CI 2.4-5.7), in Helsinki the risk was increased for rhinoconjuntivitis (OR 4.9, 95%CI 1.8-13.4). The results indicate that a strongly (≥4.3mm) positive SPT to Dp may be a reliable indicator of clinically relevant sensitization in mono and polysensitized subjects. In Portugal positive SPT to Dp is often associated with asthma, in Finland with rhinoconjunctivitis.