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Persistence of Airway Obstruction and Hyperresponsiveness in Subjects With Asthma Remission: Conclusion

Published in Asthma

More than 50 percent of subjects with mild increases in airway response to histamine denied symptoms suggestive of asthma. This is similar to what has been reported by Woolcock et al28 showing that 32 percent of adults with airway hyperresponsiveness never had symptoms suggestive of asthma. This suggests that for a similar degree of airway responsiveness, there may be marked differences in perception of asthma symptoms from one subject to another, although why these differences occur is still to be documented.
Different factors may be involved in the reduction of severity of asthma and “virtual” or true remissions. First, “remissions” of asthma were almost exclusively observed in atopic subjects (28 of our 30 subjects), suggesting that they are possibly in relation with environmental changes such as reduced exposure to relevant allergens or a reduction in immunologic response. This is supported by the observation that most of these subjects avoided exposure to antigens to which they were sensitized. Canadian family pharmacy Link Most of our subjects had mild hyperresponsiveness and little variations of expiratory flow rates (mean daily variation <10 percent). It is possible that they did not encounter in their daily activities or avoided sufficiently triggers that could have caused symptoms.
Furthermore, many symptoms related to asthma are not appreciated as being abnormal. Cockcroft et al29 showed that symptomatic individuals may have sensations that they regarded as normal but were reproduced by the histamine-induced airway obstruction. Some of our subjects reported occasional asthma-like symptoms, especially following allergic exposure, on the initial questionnaire and on diary cards, but they did not associate these with asthma.
Another explanation of the reduced symptom report is the possibility of a low level of perception of bronchoconstriction. Poor perception of bron-chospasm has often been described in asthmatics.30,31 The degree of perception of asthmatics “in remission” was similar to that of controls.
The lack of symptoms can also be the result of a possible change in immunologic response, although this has to be further assessed. Allergic asthma mainly results from three factors: the dose of antigen, nonallergic airway responsiveness, and immunologic responsiveness. About this last possibility, we can speculate that immunotherapy could have reduced immunologic response of some of these subjects. Ten ex-asthmatics had previous immunotherapy, but asthma remission appeared many years later, making the causality relationship uncertain. Five of the eight subjects in remission with normal airway responsiveness had immunotherapy, although only three had reported improvement by this treatment.