Occupational Asthma Reference

Beckett WS, Pace PA, Sferlazza SJ, Carey VJ, Weiss ST, Annual variability in methacholine responsiveness in nonasthmatic working adults, Eur Respir J, 1997;10:2515-2521,

Keywords: USA, methacholine, br, methods, standard

Known Authors

Bill Beckett, University of Rochester, NY Bill Beckett

If you would like to become a known author and have your picture displayed along with your papers then please get in touch from the contact page. Known authors can choose to receive emails when their papers receive comments.


Change in airway responsiveness is used frequently as a clinical as well as an epidemiological tool. Changes in airway responsiveness can be superior to other measures of lung function in that they are more sensitive indicators of an environmental effect. However, normal variation in test results must be defined before change can be interpreted. To characterize annual variability in airways responsiveness, we administered a high-dose methacholine challenge at 1 yr intervals for up to 4 yrs to 105 healthy, nonasthmatic working subjects. Using this high-dose protocol, the majority of tests (83%) produced at least a 20 % fall in forced expiratory volume in one second (FEV1), allowing standard calculation of the provocative dose of methacholine causing a 20% fall in FEV1 (PD20). An annual change in methacholine responsiveness by one or more doubling doses was seen in at least 30% of subjects each year. The components of variance of airways responsiveness measures were estimated to allow direct comparison of within-subject and between-subject variability. The within-subject variability in PD20, was markedly greater than the comparable within-subject variability in FEV1. Level of FEV1 and age were both significant determinants of methacholine responsiveness. Comparison of two methods of expressing methacholine responsiveness (PD20 using the full challenge up to 250 mg x mL(-1) methacholine, and the dose-response slope using data up to 32 mg x mL(-1) methacholine as the maximum dose) had similar annual variability in censored data and mixed-effects models. We then developed an approach to statistical analysis of "right-censored" methacholine challenge data using a maximum likelihood estimation under a censored Gaussian model. These studies of methacholine responsiveness provide normative data on annual test variability in healthy, nonasthmatic working adults, and show that a shorter low-dose challenge has comparable annual variability to a lengthier high-dose challenge

Full Text

Full text of this reference not available

Please Log In or Register to add the full text to this reference

Associated Questions

There are no associations for this paper.

Please Log In or Register to put forward this reference as evidence to a question.


Please sign in or register to add your thoughts.

Oasys and occupational asthma smoke logo