Asthma: patients and clinicians were not good at estimating peak flows.

Clinical bottom line (level 4)

  1. Neither clinicians or patients accurately judged peak flows - though patients were better.
  2. Patients were not very good at assessing changes in their peak flows over time, though were better at guessing when it was much worse than usual.
Shim and Williams: American Journal of Medicine 1980; 68: 11-13
Expires November 2002

The study

Setting: acute hospital, USA

96 patients (aged ?, ?% male) asthma

Excluded if
  • never used peak-flow meter before
  • inability to use meter



    • Independent ?blinded reference standard, applied in all patients from a consecutive appropriate spectrum.
    Reference standard:
    • peak flow meter
    Diagnostic test:
    • 35 patients with asthma asked to estimate their peak flow
    • 61 patients hospitalised with asthma asked to assess the trend of their airway obstruction
    • 6 respiratory physicians asked to estimate the peak flow in 17 patients

    The evidence


    differential diagnosis number of patients prevalence
    (95% CI)
    patients' perception much better 21 33%
    (22% to 45%)
    patients' perception better 17 22%
    (13% to 31%)
    patients' perception same 2 4.35%
    (0.0% to 10%)
    patients' perception worse 9 26%
    (12% to 41%)
    patients' perception much worse 11 69%
    (46% to 91%)

    • 63% (95% CI: 47% to 79%) of patients' estimates were within 20% of measured PEFR.
    • 44% (95% CI: 31% to 56%) of clinicians' estimates were within 20% of measured PEFR.

    Comments

    1. PEFR is one measurement used to determine severity and improvement of asthma.
    2. Patients more accurate perception of worsening, gives support to use symptoms and objective measures of lung function, in the classification of asthma severity.

    Citation

    1. Shim CS, and Williams MH: Evaluation of the severity of asthma: patients versus physicians. American Journal of Medicine 1980; 68: 11-13
    Search Terms: reference from asthma chapter in Lee, Hsu and Stasior- Quick Consult Manual to Evidence-Based Medicine
    Contributor: Chris Ball and Clare Wotton, June 2000
    Reviewer: Daniel Sontheimer

    Clinical Question.
    Patient asthma
    Intervention or Exposure patient and physician estimated peak flow
    Outcome diagnosis