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Keywords:

  • allergic rhinitis;
  • bronchial hyperreactivity;
  • children;
  • methacholine challenge;
  • rhinitis duration

Allergic rhinitis (AR) is a strong risk factor for the asthma inception (1). The forced expiratory flow at the 25 and 75% of the pulmonary volume (FEF25–75) is a reliable marker of early bronchial impairment in allergic rhinitis (2). On the other hand, bronchial hyperreactivity (BHR) is a paramount feature of asthma and may be observed in a high proportion of patients with AR (3).

As AR may be considered the first step of a progression toward asthma, the WHO document ‘the impact of allergic rhinitis on asthma’ (ARIA) clearly underlined the role of allergic rhinitis as risk factor for asthma development (4). Recently, some risk factors associated with BHR have been detected in adult patients with AR (5). Therefore, the aims of the present study were (i) to evaluate BHR in a group of AR children and (ii) to investigate the possible role of independent predictors in the association with BHR.

This study included 190 children (110 men, median age 12) with moderate-severe persistent AR, perceiving nasal symptoms alone, and with normal FEV1 values (≥ 80% of predicted) were consecutively evaluated. We excluded all the children whit asthma diagnosis and use of symptomatic drugs (potentially interfering).

Methacholine bronchial challenge was performed as previously reported (5), and three categories of BHR were considered on the basis of PC20: severe PC20 < 1 mg/ml; mild PC20 between 1 and 4 mg/ml; borderline PC20 ranging from 4 to 8 mg/ml.

The statistical analysis was conducted following the same outline performed in the previous study conducted in adult patients (5), using the software program statistica (Statsoft, Milan, Italy).

Patients were studied on the base of their methacholine (MCH) response: 37 children turned out to be MCH negative, 90 children were borderline, and 63 patients were MCH positive. There were 18 patients with PC20 < 1 mg/ml (severe) and 45 with PC20 between 1 and 4 mg/ml (mild). There was a prevalence of men concerning severe BHR, and disease duration was different in the four groups of patients: the more severe was the category of BHR, the longer was the rhinitis duration (Fig. 1).

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Figure 1.  Rhinitis duration in the four groups of patients according to their category of BHR.

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Spirometric parameters were also significantly different in the four groups of patients; in particular both FEV1 and FEF25–75 values were significantly lower in the severe BHR group of patients (P < 0.0001).

Patients with severe BHR were more frequently positive to house dust mites, Parietaria and Graminae. The combination of sensitization to Parietaria and house dust mites resulted more frequently the patients with severe BHR (P < 0.0001).

A multivariate logistic analysis was performed to evaluate the role of possible predictors for severe BHR: three predictors turned out to be significantly associated with severe BHR: rhinitis duration > 4 years (ORAdj: 3.4), and FEF25–75 ≤ 74% of predicted (ORAdj: 2.8), and sensitization to Parietaria and house dust mites (ORAdj: 2.4). The model’s discriminative ability is very satisfactory, being the AUC = 0.89.

Therefore, this study may be considered confirmatory of the previous study as a remarkable percentage of these patients show BHR (33.2%). Secondly, the most clinically relevant finding of this study is represented by the suggestion of carefully considering some risk factors such as the sensitization to Parietaria and mites, the duration of allergic rhinitis, and borderline values of FEF25–75.

Therefore, from a clinical point of view, it appears to be mandatory to evaluate in each children with moderate-severe persistent AR the type of sensitization, the duration of nasal symptoms, and to consider of performing spirometry. Thus, as suggested by the ARIA document (4), a spirometry should be performed, also in absence of overt asthmatic symptoms, in patients with moderate-severe persistent allergic rhinitis with these risk factors to prematurely detect the possible presence of severe BHR.

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