Table 4

 Sensitivity, specificity and Youden’s Index for operational definitions based on self-reported symptoms and medication use*

Operational definitionsSensitivity (%)Specificity (%)Youden’s Index
Ct, concurrent; post, post-test; Rx, medication use; Sx, symptoms.
*With findings from serial peak expiratory flow as the standard for workplace exacerbation of asthma.
†Combinations of operational definitions were included if Youden’s Index ⩾0.30.
Symptoms and medication use reported concurrent with serial testing
Symptoms62540.16
Medication use62650.27
Symptoms and medication use reported post-test
Symptoms15870.02
Medication use15890.04
Combinations of self-reported operational definitions †
    Combinations of two
        Both Ct54780.32
        Ct Rx or post Rx69610.30
    Combinations of three
        Both Ct or post Sx62680.30
        Both Ct or post Rx62710.33
        Either Sx and Ct Rx54760.30
        (Ct Rx or post Sx) and Ct Sx54760.30
        Either Rx and Ct Sx54770.31
        Both post or Ct Rx69620.31
    Combinations of four
        Both Ct or both Sx54760.30
        Both Ct or both post62730.35
        Both Ct or (Ct Sx and post Rx)54770.31
        Both Ct or (Ct Rx and post Sx)54760.30
        (Ct Sx or post Sx) and (Ct Rx or post Rx)62730.35
        (Ct Sx or post Rx) and (Ct Rx or post Sx)62710.33