Which skin prick test wheal size detects true allergy to Salsola kali?

Summary: Background. Sensitization to Salsola kali (Sk) weed pollen allergen is the most common cause of seasonal allergic rhinitis (SAR) in Middle East countries. Aim. To identify Salsola kali skin prick test (SkSPT) wheal size cut-off, able to determine true allergy among adult patients with moderate to severe SAR, who are in need of Salsola kali allergen specific immunotherapy (SkAIT). Methods. In 151 adults with moderate to severe SAR, mean age 32.79 ± 10.79 years, of both gender (females: 43.05%), with a positive SkSPT, (i.e., cut off wheal longest diameter of 3 mm) and one or more other local weed pollens, Salsola kali nasal provocation test (SkNPT) was carried out. Response was assessed both subjectively, with scores, and objectively, by measuring peak nasal inspiratory flow (PNIF). Safety profile of SkNPT was assessed using peak expiratory flow rate (PEF) measurements. Results. SkNPT positive response was found in 125 patients (82.78%). Mean skin prick test (SPT) wheal size to Sk was bigger in the nasal provocatin test (NPT) positive group (9 mm) compared to the NPT negative patients (5 mm), p less than 0.0001. ROC analysis showed that a SPT wheal size to Sk at the threshold of > 7.5 mm enabled identification of SkNPT positivity with a sensitivity of 73.6% and specificity of 100.0% (area under the curve 0.9498, standard error 0.01808; 95% confidence interval (CI): 0.9144 to 0.9853; p less than 0.0001). Conclusions. SPT wheal size of 3 mm might overestimate the presence of real allergy to Sk in a desert environment. A SPT wheal size > 7.5 mm for Sk appears to distinguish individuals who develop disease from those who does not. Physicians should select the proper SPT wheal size value as an appropriate criterion according to the allergen than using a uniform cut off value in patients eligible for SkAIT.

Role of nasal challenge and local eosinophilia in indirect exposure to cat in allergic rhinitis patients.

Summary: Introduction. Sensitization to cat allergens is common worldwide. Currently, there is a trend towards costly and often unavailable diagnostic analysis. Objectives. The aim is to assess the reliability of skin prick test (SPT) and serum specific IgE (ssIgE) to cat sensitization, by performing nasal challenge test (NCT) in a community with low cat ownership but common presence of stray cats. Patients and methods. Forty-one pa-tients with perennial allergic rhinitis (AR) who were mono or polysensitized (including cat) were included. We had 31 cat non-owners and 10 present cat owners. SPT (> 5 mm / diameter), ssIgE (≥ 0.70 IU/ml), nasal smear for eosinophil (Eo) and NCT were compared between groups. Outcomes included nasal challenge score, nasal Eo positivity, peak inspiratory and expiratory flow (PIF and PEF) 2 and 8 hours after the NCT, and were compared to baseline. Results. Baseline SPT wheal size and ssIgE level were similar in both groups. NCT positivity was more frequent in cat owners. The strongest nasal reaction was on the top concentration in both groups. Nasal Eo positivity in cat owners was higher before and 2 hours after NCT, but similar to non-owners at last measurement. NCT positive cat non-owners had bigger SPT wheal size than NCT negative non-owners, but smaller than NCT positive cat owners. In contrast to PEF, a significant fall in PIF was noticed in both groups. Mono and polysensitised patients showed similar NCT positivity. Conclusion. Stray cats may pose a relevant risk of developing perennial AR. Regardless of cat ownership status, SPT and ssIgE should be the first diagnostic tool. Nasal Eo and NCT seem to be good diagnostic tools in cat non-owners if diagnosis is elusive.