Nasal provocation with histamine in allergic rhinitis patients: clinical significance and reproducibility

Summary In a selected group of rhinitis patients (n= 12) with an IgE-mediated allergy to house dust mites, the nasal response to insufflation of histamine chloride appeared to be related to symptom scores obtained from the patients. In contrast to the sum of the nasal airway resistances (NAR) induced by all doses of histamine, the total amount of secretion and total number of sneezes could be predicted from clinical scores. The reproducibility of the nasal provocation test was tested by comparison of the test results in two sessions with a 1-week interval. The correlation between both sessions was highest with respect to nasal secretion (r=0.87; P<0.001) and the number of sneezes (r=0.76; P=0.004). The correlation coefficient was 0.71 (P=0.01) when the nasal airway resistance was used in the assessment of nasal response. A good reproducibility of the nasal provocation test was also obtained using an end-point titration method and determining the concentration required to produce 0.5 ml secretion and/or five sneezes as the end-point (r=0.76; P=0.004). The concentration required to double nasal airway resistance yielded a correlation coefficient of 0.56 (P=0.052). We conclude that the clinical significance of nasal provocation with histamine increases when, besides nasal airway resistance, the amount of secretion and the number of sneezes is used in the assessment of the nasal response. Moreover, the reproducibility is better with respect to these symptoms than to nasal airway resistance. With respect to a better reproducibility, the use of a summed nasal airway resistance is preferable above the end-point concentration required for a 100% NAR increase.