Comparison of conjunctival and nasal provocation test in allergic rhinitis to house dust mite

Nasal allergen provocation tests (NPTs) are useful in confirming the diagnosis of allergic rhinitis, if data obtained by clinical history, skin tests and specific IgE determinations are not conclusive. Since NPTs are laborious, conjunctival provocation tests (CPTs) appear as an attractive alternative. The concordance of CPTs and NPTs with house dust mite allergen extract in sensitized and nonsensitized subjects should be evaluated.

50 otherwise healthy subjects with self-reported house dust mite allergy and positive skin prick tests and serum specific IgE to Dermatophagoides pteronyssinus and 45 sex- and age-matched healthy controls without allergic symptoms were included. For NPTs, 100 microl allergen extract [10,000 allergy units (AU/ml)] were applied to the less congested nasal cavity. A clinical symptom score and active anterior rhinomanometry were employed to assess the response. For CPTs, 50 microl low-concentrated D. pteronyssinus extract (1,000 AU/ml), and if negative, 50 microl normally concentrated extract (10,000 AU/ml) were applied to the lower conjunctival sac. The response was assessed employing clinical symptom scores.

NPTs and CPTs yielded concordant results in 90% of the subjects successfully tested (Cohen's kappa = 0.78, p < 0.0001). The diagnostic efficacy of the CPT, with the NPT as the reference method, was 89%, whether or not conjunctival symptoms had been reported in addition to rhinitis symptoms. Both techniques were judged almost equally uncomfortable.

CPTs are an acceptable alternative to NPTs in patients with allergic rhinitis to house dust mite, even if they have no conjunctival symptoms.