[THE RELATIONSHIP AMONG BRONCHIAL HYPERSENSITIVITY, BRONCHIAL HYPER REACTIVITY, AND BRONCHIAL HYPERRESPONSIVENESS IN ASTOGRAPH]

Abstract

Background: Bronchial hyperresponsiveness testing is useful for diagnosing and predicting the risk of bronchial asthma attacks. The Astograph is a tidal breathing method often used in as bronchial provocation testing in Japan. The minimum methachorine dose (Dmin) indicates bronchial sensitivity and is used mainly as an index of bronchial hyperresponsiveness. However, Dmin does not measured hyperresponsiveness, it cannot be compared directly with PC₂₀ in standard methods using FEV₁.

Methods: We investigated the relationship among sensitivity, reactivity, and hyperresponsiveness with the Astograph. We recruited 142 patients with confirmed or suspected bronchial asthma from outpatient clinic at St. Marianna University School of Medicine, Yokohama City Seibu Hospital. We calculated Dmin, SGrs/Grscont, PD_35Grs, and PD_15Grs compared them as bronchial hyperresponsiveness indices.

Results: Subjects had suspected asthma (n=103), or required assessment of asthma remission (n=39). There were significant relationships between logDmin and logPD_35Grs (r=0.838, p<0.001), and between parameters and SGrs/Grscont (log PD_35Grs r=-0.504, p<0.001, strong, logDmin: r=-0.191, p=0.023, weaker). Among subjects positive for hypersensitivity, (Dmin<10), 38 (36.5%) showed negative hyperresponsiveness (PD_35Grs>25). PD_15Grs was a strongly and significantly correlated with Dmin and PD_35Grs. The ROC curve to detect PD_35Grs<25, showed that the cutoff of PD_15Grs was 10.7 (AUC 0.983, sensitivity 0.984, specificity 0.905).

Conclusion: In Astograph, evaluation of bronchial hyperresponsiveness, we focused on relationship differences between sensitivity and reactivity, and hyperresponsiveness. We revealed the usefulness of the PD_15Grs evaluation method.

Keywords: bronchial asthma Astograph; bronchial hyperresponsiveness.