Consistency of diagnostic criteria for asthma from Laënnec (1819) to the National Asthma Education Program (1991).

Interpretation of longitudinal trends in asthma incidence, prevalence, and mortality must assume consistency in the diagnostic criteria used by clinicians. This review samples the textbook and clinical literature on clinical recognition and diagnosis of asthma from Laënnec (1819) to the National Asthma Education Program (1991), which introduced as a standard for clinical care a set of diagnostic criteria based on laboratory confirmation. There is great consistency among authors in descriptions of the cardinal diagnostic criteria of asthma as episodic dyspnea punctuating periods of normal breathing, generally associated with expiratory wheezing and prolonged expiration. In contrast, there is much greater variation in the formal definitions or explanations of the presumed pathophysiology of the disorder. It is much more difficult to document the actual diagnostic criteria used by practicing clinicians in the past, but these findings indicate a high degree of consistency over 172 years in what was taught and was considered acceptable practice. The literature on asthma contains several medical classics, a few gems of insight, and some unusual authors; some of these are noted in the discussion, as is the strong tradition of reciprocity in American and British medicine.