Table 4—

Predictors of perception of bronchoconstriction during methacholine tests

Odds ratio95% Confidence interval
Year of study 1998–1999 versus 1992–19932.782.04–3.78
Age per year0.970.94–0.99
Sex female versus male1.551.14–2.10
Degree of bronchoconstriction per % fall of FEV11.091.06–1.13
PD20 per band#0.640.47–0.89
Atopy yes versus no1.771.21–2.59
  • Data drawn from both surveys.

  • FEV1: forced expiratory volume in one second

  • PD20: provocative concentration causing a 20% fall in FEV1.

  • #: <200 µg, 200–1000 µg, 1001–6400 µg, >6400 µg

  • : at least one positive allergen skin test (wheal ≥4 mm greater than that of saline control) 10