Asthma: acute exacerbation: FEV1 may help predict which patients will relapse or require admission.

Clinical bottom line (level 4)

  1. Patients with acute asthma who had an initial FEV1 < 0.7 l/min were more likely to require admission or suffer a relapse in the next 5 days (NNF = 4 for 5 days) .
Worthington and Ahuja: Canadian Medical Association Journal 1989; 140: 153-156
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, acute hospital, Canada

104 patients (aged ?, 55% female) acute bronchospasm due to asthma

Excluded if
  • < 15, > 35
  • bronchospasm for other reasons
  • respiratory distress severe enough to preclude spirometry before treatment



    • Factors studied:
  • admitted or relapse
  • initial FEV 1 0.7 or less
  • FEV 1 after decision to admit or discharge 2.1 or less


    • All patients had nebulised salbutamol, with iv aminophylline and hydrocortisone if necessary.

    92% followed for 5 days
    Outcomes studied:
  • admitted or relapsed

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    admitted or relapsed 5 days 20/104 20.8%
    (12.7% to 29.0%)

    prognostic factor for
    admitted or relapsed     		time to outcome unadjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    initial FEV 1 0.7 or less 5 days 2.7
    (1.3 to 5.7)     		4
    (1 to 22)
    FEV 1 after decision to admit or discharge 2.1 or less 5 days 2.6
    (0.95 to 7.2)     		6
    (-2 to 180)

    Comments

    1. The study was too small and failed to adjust for confounding factors to exclude useful prognostic information from FEV1, making its conclusions much less useful.

    Citation

    1. Worthington JR, and Ahuja J: The value of pulmonary function tests in the management of acute asthma. Canadian Medical Association Journal 1989; 140: 153-156
    Search Terms: reference from review article
    Contributor: Chris Ball and Clare Wotton, November 2000
    Reviewer: Mitsuhiro Kamei

    Clinical Question.
    Patient exacerbation of asthma, bronchospasm due to asthma
    Intervention or Exposure FEV1 0.7 l/min or less
    Outcome admission or relapse