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Normal range of methacholine responsiveness in relation to prechallenge pulmonary function. The Normative Aging Study
G T O'Connor1, D Sparrow, S T Weiss
1Pulmonary Center, Boston University School of Medicine.
Chest
|March 1, 1994
Summary
Normal ranges for methacholine airway responsiveness depend on baseline lung function. Establishing FEV1-specific normal limits for methacholine challenge did not improve asthma detection sensitivity or specificity.
Area of Science:
- Pulmonary Medicine
- Respiratory Physiology
Background:
- Methacholine airway responsiveness is linked to baseline pulmonary function.
- Normal ranges for responsiveness at specific lung function levels are not well-established.
Purpose of the Study:
- To examine methacholine airway responsiveness in relation to prechallenge pulmonary function levels.
- To determine if FEV1-specific normal ranges improve asthma detection.
Main Methods:
- Studied 547 middle-aged/elderly men with normal baseline lung function.
- Correlated cumulative methacholine dose for 20% FEV1 decline (PD20FEV1) with prechallenge FEV1.
- Applied FEV1-specific cut-offs to a larger sample (838 men).
Main Results:
- PD20FEV1 positively correlated with prechallenge FEV1 percent predicted (r=0.35).
- The lower limit of normal PD20FEV1 varied with prechallenge FEV1.
- FEV1-specific cut-offs did not enhance sensitivity or specificity for asthma/wheezing detection.
Conclusions:
- Provides FEV1-specific lower limits of normal for PD20FEV1.
- FEV1-specific limits offer no diagnostic advantage over a single normal limit for asthma/wheezing.
- Methacholine challenge's utility for asthma detection may not be improved by lung function-specific normal ranges.