Asthma: spirometry helped predict patients requiring admission.

Clinical bottom line (level 4)

  1. Patients with acute asthma who had pre-treatment FEV 1 0.61 or less, or a post-treatment FEV 1 1.61 or less were more likely to be admitted immediately or have significant airflow obstruction in the next two days (NNF = 2 for 48 hours) .
Nowak et al: JACEP 1979; 8: 9-12
Expires November 2002

The study

Inception cohort study with unblinded, unobjective outcomes, not adjusted for confounding factors, not validated in an independent set of patients.

Setting: emergency department, university hospital, USA

82 patients (aged mean 27 years, 67% female) with 85 acute exacerbations of asthma

Excluded if
  • known cardiac or lung diseases



    • Factors studied:
  • hospital admission or significant airflow obstruction
  • pretreatment FEV 1 = 0.61
  • post-treatment FEV 1 = 1.61




    • 100% followed for 24-48 hours
    Outcomes studied:
  • required hospital admission or subsequent significant airflow obstruction based on worsening symptoms and need to re attend emergency department. Clinicians who decided on admission or discharge were blinded to the spirometry results.

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    required hospital admission or subsequent significant airflow obstruction 24-48 hours 50/82 61%
    (50% to 72%)

    prognostic factor for
    required hospital admission or subsequent significant airflow obstruction     		time to outcome unadjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    pretreatment FEV 1 = 0.61 24-48 hours 2.11
    (1.36 to 3.28)     		2
    (1 to 7)
    post-treatment FEV 1 = 1.61 24-48 hours 2.31
    (1.35 to 3.94)     		2
    (1 to 9)

    Comments

    1. No information was given on the duration of stay and subsequent symptoms of patients who were admitted to hospital.
    2. PEF measurement in the emergency department is easier to administer than measurement of FEV1.0 and more useful to teach patients.

    Citation

    1. Nowak RM, Gordon KR, Wroblewski DA, et al: Spirometric evaluation of acute bronchial asthma. JACEP 1979; 8: 9-12
    Search Terms: asthm* in Cochrane
    Contributor: Chris Ball and Clare Wotton, June 2000
    Reviewer: Mitsuhiro Kamei

    Clinical Question.
    Patient asthma
    Intervention or Exposure FEV1
    Outcome admission to hospital