| Abstract: |
Rationale: Patients with fatal asthma have been hypothesized as representing two distinct subgroups according to the onset of symptoms prior to death. Objectives: To determine if these two groups may be reliably identified and determine if they differ clinically and pathologically. Methods: Patients with autopsies, 2-34 years of age, dying from asthma were classified slow-onset (Type 1) or rapid-onset (Type 2). The consistency of classification by two independent observers was determined. Clinical and pathologic data was compared between groups. Main results: Among 37 subjects there were 21 Type 1 and 16 Type 2 mortalities. Inter-observer agreement was good; κ 0.63 (95% CI 0.38, 0.87). Subjects did not differ by age, race, sex, presence of obesity, insurance status, or use of corticosteroids. Type 1 mortalities were hospitalized more (2.5 + 1.3 versus 0.1 + 0.1; p = 0.048) and made more emergency room visits (10.5 + 4.9 versus 0.8 + 0.2; p = 0.023) in the year prior to death than Type 2 mortalities. At autopsy, bronchial eosinophils (p < 0.025) and bronchiolar basement membrane thickening (p < 0.05) were more predominant in Type 1 mortalities compared with Type 2. Airway wall neutrophils were uncommon in both groups. Conclusion: Good inter-observer agreement exists in classifying patients dying from asthma according to whether the onset of symptoms was slow or rapid in onset. Slow-onset patients had a predominance of eosinophils and basement membrane thickening and higher health care utilization. These differences support the validity of classifying asthma mortalities into these distinct subgroups. |
