Risk Factors for Near-fatal Asthma

Abstract

We prospectively recruited patients admitted to the hospital with severe asthma to comprehensively evaluate the association of historical and physiologic features with the risk of near-fatal asthma (NFA). A case-control study design was used. All patients admitted with NFA (cases) were identified prospectively and compared with asthma patients admitted during the same period without respiratory failure (controls). Nineteen cases (age: 40.2 +/- 12.0 yr) (mean +/- SD) and 80 controls (age: 36 +/- 13.5 yr) were enrolled. Duration of asthma, gender, smoking status, ethnicity, and prevalence of atopy were similar in the case and control groups. More than 80% of patients in both groups reported worsening symptoms for more than 48 h before admission, and more than 50% were worse for longer than 7 d. There was no difference in degree of airways obstruction or bronchial hyperresponsiveness (PC20). Perception of dyspnea was similar in the cases and controls, but among cases the males had greater impairment than the females (Borg score: 1.9 +/- 1. 4 versus 3.9 +/- 1.2: p = 0.05). Univariate analysis identified a history of previous mechanical ventilation (OR: 27.5; 95% CI: 6.60 to 113.7), admission to the intensive care unit (ICU) (OR: 9.9; 95% CI: 3.0 to 32.9), history of worse asthma during January and February (OR: 3.5; 95% CI: 1.0 to 11.8), and use of air-conditioning (OR: 15.0; 95% CI: 1.3 to 166) as risk factors for NFA. Of concern was the dependence of most patients (59.8%) on the emergency department (ED) for initial care, and the small number of cases (16%) in which patients visited a physician before admission to the hospital. We have confirmed risk factors identified previously in retrospective studies of fatal and NFA, and have also shown that hospitalized patients with asthma, irrespective of severity of their asthma, share several characteristics, especially in terms of their failure to respond to worsening asthma.

Characterization of the severe asthma phenotype by the National Heart, Lung, and Blood Institute's Severe Asthma Research Program

“…These findings support previous studies that identify a history of a severe exacerbation as one of the strongest risk factors for additional severe exacerbation or near-fatal event. [21][22][23][24] Low lung function is not a required criterion in the ATS definition of severe asthma, but 80% of severe subjects had persistent airflow obstruction (FEV 1 < 80%), and nearly half had a baseline FEV 1 < 60% when bronchodilators were withheld before spirometry. Reversibility testing using high doses of albuterol (6-8 puffs), however, showed more than 12% improvement in FEV 1 in the majority (61%) of all severe subjects, even though they had not withheld their bronchodilators before testing.…”

Evolving Differences in the Presentation of Severe Asthma Requiring Intensive Care Unit Admission

“…Risk factors for asthma death include severe disease, recent hospital visits for asthma, increased medication use, and noncompliance and/or discontinuity of medical care [5,6,7]. The strongest single risk factor for death from asthma is a history of prior intubation for an asthmatic attack [5].…”

Perception of Dyspnea during Histamine- and Methacholine-Induced Bronchoconstriction

“…Poor perception has been found to be directly related to advanced age [23], male gender [24]and increased severity of asthma [25]. A positive effect of inhaled corticoids on perception has recently been reported [16, 26].…”