title: Spirometry or Body Plethysmography for the Assessment of Bronchial Hyperresponsiveness?
abstract: Methacholine testing is one of the standard tools for the diagnosis of mild asthma, but there is little information about optimal outcome measures. In this study a total of 395 college students were tested by the ATS dosimeter protocol for methacholine testing, with minor modification. Body plethysmography and spirometry were measured after each inhalation step. The end-of-test-criteria were (i) decrease in forced expiratory volume in 1 s (FEV1) of ≥ 20 % and (ii) doubling of specific airway resistance and its increase to ≥ 2.0 kPa∙s. The results were expressed by receiver operating characteristic (ROC) plots using questionnaire answers as a reference. The areas under the ROC curves were iteratively calculated for a wide range of thresholds for both measures. We found that ROC plots showed maximal sensitivities of about 0.5-0.6 for FEV1 and about 0.7 for specific airway conductance (sGt), with similar specificities of about 0.7-0.8 taking questions with the known high specificity as references. Accordingly, larger maximal areas under the ROC curve were observed for body plethysmography, but the differences were small. A decrease in FEV1 of about 15 % and a decrease of sGt of about 60 % showed the largest areas under the ROC curves. In conclusion, body plethysmography yielded better sensitivity than spirometry, with similar specificity. However, replacing the common spirometric criterium for a positive test (20 % decrease in FEV1 from baseline) by the optimal body plethysmographic criterium would result in an increase of false positive tests from about 4 to 8 % in healthy young adults.
authors.affiliation: Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr University, 1 Bürkle-de-la-Camp-Platz, 44789, Bochum (IPA), Germany. merget@ipa-dguv.de.
authors.forename: R
authors.initials: R
authors.lastname: Merget
authors.affiliation: Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr University, 1 Bürkle-de-la-Camp-Platz, 44789, Bochum (IPA), Germany.
authors.forename: F
authors.initials: F
authors.lastname: Nensa
authors.affiliation: Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr University, 1 Bürkle-de-la-Camp-Platz, 44789, Bochum (IPA), Germany.
authors.forename: E
authors.initials: E
authors.lastname: Heinze
authors.affiliation: Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr University, 1 Bürkle-de-la-Camp-Platz, 44789, Bochum (IPA), Germany.
authors.forename: D
authors.initials: D
authors.lastname: Taeger
authors.affiliation: Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr University, 1 Bürkle-de-la-Camp-Platz, 44789, Bochum (IPA), Germany.
authors.forename: T
authors.initials: T
authors.lastname: Bruening
mesh_terms: D000328:Adult; D016535:Bronchial Hyperreactivity / Q000175:diagnosis*; D016022:Case-Control Studies; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D010993:Plethysmography, Whole Body / Q000379:methods*; D012372:ROC Curve; D013147:Spirometry / Q000379:methods*; D055815:Young Adult
keywords: Body plethysmography; Bronchial hyperresponsiveness; Dosimeter; Methacholine; Spirometry