Document Detail


Different response to doubling and fourfold dose increases in methacholine provocation tests in healthy subjects.
MedLine Citation:
PMID:  11083688     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
RATIONALE: In a modified methacholine provocation test that was used to study changes in airway responsiveness to occupational irritants or sensitizers in healthy subjects, two protocols were used: a long protocol (doubling methacholine concentrations between dose steps) or a short protocol (fourfold increases in concentration). This modified methacholine provocation allows measurements of the provocative dose causing 20% decrease in FEV(1) (PD(20)) in a high proportion of a normal population. METHODS: The distribution of PD(20) was investigated in healthy nonatopic men without history of allergy or asthma symptoms using the long protocol (n = 101) or the short protocol (n = 309). In addition, 30 healthy subjects underwent methacholine provocation tests using both protocols. RESULTS: PD(20) was defined in 79% of subjects with the long protocol and in 48% of subjects with the short protocol. The provocative concentration of methacholine causing a 20% decline in FEV(1) (PC(20)) and PD(20) were significantly lower using the long protocol: long-protocol PC(20) (median [25th to 75th percentile]), 19.9 mg/mL (3.9 to > 32 mg/mL) compared with short-protocol PC(20), > 32 mg/mL (8.7 to >32 mg/mL; p < 0.0001); long-protocol PD(20), 4.2 mg (1.6 to 20 mg) compared with short-protocol PD(20), > 13.7 (2.6 to > 13.7 mg; p = 0. 006). The differences in PD(20) using short and long protocols were confirmed in a randomized trial of 30 healthy subjects tested with both protocols. CONCLUSION: Using doubling concentrations, PC(20) and PD(20) could be defined in a higher proportion of healthy subjects than a protocol using fourfold dose increases. Furthermore, the doubling protocol results in a PD(20) estimate that is less than half the value obtained when using a protocol with fourfold concentrations between dose steps. The difference remains, whether the methacholine effect is regarded as cumulative or noncumulative. The explanation for the difference between the protocols is unclear.
Authors:
B M Sundblad; P Malmberg; K Larsson
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Chest     Volume:  118     ISSN:  0012-3692     ISO Abbreviation:  Chest     Publication Date:  2000 Nov 
Date Detail:
Created Date:  2000-11-29     Completed Date:  2000-12-14     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0231335     Medline TA:  Chest     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1371-7     Citation Subset:  AIM; IM    
Affiliation:
Programme for Respiratory Health and Climate, National Institute for Working Life, Stockholm, Sweden. Britt-Marie.Sundblad@niwl.se
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MeSH Terms
Descriptor/Qualifier:
Adult
Aged
Allergens / adverse effects
Bronchial Hyperreactivity / physiopathology
Bronchial Provocation Tests / methods*
Bronchoconstrictor Agents / administration & dosage,  diagnostic use*
Chi-Square Distribution
Dose-Response Relationship, Drug
Female
Forced Expiratory Volume / drug effects
Humans
Irritants / adverse effects
Male
Methacholine Chloride / administration & dosage,  diagnostic use*
Middle Aged
Occupational Exposure
Spirometry
Statistics, Nonparametric
Time Factors
Chemical
Reg. No./Substance:
0/Allergens; 0/Bronchoconstrictor Agents; 0/Irritants; 62-51-1/Methacholine Chloride

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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