Abstract
BackgroundPrecision and accuracy assurance in cardiopulmonary exercise testing (CPET) facilitates multicenter clinical trials by maximizing statistical power and minimizing participant risk. Current guidelines recommend quality control that is largely based on precision at individual testing centers (minimizing test–retest variability). The aim of this study was to establish a multicenter biological quality control (BioQC) method that considers both precision and accuracy in CPET.MethodsBioQC testing was 6-min treadmill walking at 20 W and 70 W (below the lactate threshold) with healthy non-smoking laboratory staff (15 centers; ~16 months). Measurements were made twice within the initial 4 weeks and quarterly thereafter. Quality control was based on: 1) within-center precision (coefficient of variation [CV] for oxygen uptake [V̇O2], carbon dioxide output [V̇CO2], and minute ventilation [V̇E] within ±10 %); and 2) a criterion that V̇O2 at 20 W and 70 W, and ∆V̇O2/∆WR were each within ±10 % predicted. “Failed” BioQC tests (i.e., those outside the predetermined criterion) prompted troubleshooting and repeated measurements. An additional retrospective analysis, using a composite z-score combining both BioQC precision and accuracy of V̇O2 at 70 W and ∆V̇O2/∆WR, was compared with the other methods.ResultsOf 129 tests (5 to 8 per center), 98 (76 %) were accepted by within-center precision alone. Within-center CV was <9 %, but between-center CV remained high (9.6 to 12.5 %). Only 43 (33 %) tests had all V̇O2 measurements within the ±10 % predicted criterion. However, a composite z-score of 0.67 identified 67 (52 %) non-normal outlying tests, exclusion of which coincided with the minimum CV for CPET variables.ConclusionsStudy-wide BioQC using a composite z-score can increase study-wide precision and accuracy, and optimize the design and conduct of multicenter clinical trials involving CPET.Trial registrationClinicalTrials.gov identifier: NCT01072396; February 19, 2010.Electronic supplementary materialThe online version of this article (doi:10.1186/s12890-016-0174-8) contains supplementary material, which is available to authorized users.
Highlights
Precision and accuracy assurance in cardiopulmonary exercise testing (CPET) facilitates multicenter clinical trials by maximizing statistical power and minimizing participant risk
The number of biological quality control (BioQC) tests per center varied from five to eight, depending on the length of time the center was active in the trial (16.3 ± 3.1 months [range 10 to 20 months])
This resulted in a total of 129 BioQC tests performed (6.5 ± 1.2 per center), with each center having between 10 and 28 non-repeated pairs of BioQC tests
Summary
Precision and accuracy assurance in cardiopulmonary exercise testing (CPET) facilitates multicenter clinical trials by maximizing statistical power and minimizing participant risk. Assurance of study-wide precision and accuracy has a major impact on the design and conduct of multicenter trials, by maximizing statistical discriminatory power, and minimizing laboratory burden and participant risk. The American Thoracic Society (ATS)/American College of Chest Physicians (ACCP) [4], American Heart Association [3], and European Respiratory Society (ERS) [7, 12] have published CPET recommendations and standards. These give “best practice” for calibration and QC, and provide typical coefficients of variation (CV) for physiological measurements. Rather than assuring the precision and accuracy of the individual mechanical–metabolic power coupling, the basis of the acceptability criteria (the “target range”) in Brawner et al [21] was wide, in part due to differences in weights of the volunteers used to develop the normative data
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