DETERMINANTS OF RESPONSE TO INHALED IRRITANT IN ASTHMA

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Asthma affects approximately 10 million Americans, two-thirds of them children under the age of 18. Although important strides have been made in identifying aggravating environmental factors and developing more effective treatments, the prevalence and morbidity of asthma are increasing. Asthma is characterized by bronchial hyperresponsiveness to nonspecific inhaled agents, such as smoke, dusts, fumes and pharmacologics such as histamine and methacholine. In asthma, a high placebo-response rate is seen; while some of these responses represent regression to the mean of a previously highly sensitive individual, it is likely that a high degree of "true" placebo response exists. The overall hypothesis of this study is: inhalation of a placebo will offer some individuals protection against the development of bronchospasm following inhalation of methacholine. Additional specific hypotheses include: a) the presence and magnitude of a placebo response will correlate with psychological factors including personality characteristics; b) the presence and magnitude of a placebo response will be influenced by the perceived interactions/interventions between study personnel (health care providers) and research subjects; in other words, enhanced patient expectations will increase the protection against the development of methacholine-induced bronchospasm offered by placebo or by an inhaled beta agonist, salmeterol. To date, there have been no studies examining the influence of patient expectations on asthma outcomes. Additionally, there are no studies that evaluate an intervention in asthmatic patients that will enhance patient outcome expectations and presumably lead to improved lung function.