Abstract
Objective
To determine the accuracy of incremental Shuttle Walking Test (ISWT) in detecting exercise-induced bronchospasm (EIB) in adults with asthma and to verify whether there is an association of the drop in FEV1 between ISWT and cardiopulmonary exercise testing with constant-load CPET-CL.
Methods
In this cross-sectional study 32 individuals with asthma performed two ISWTs, an incremental cardiopulmonary exercise test (CPET-I) and a constant-load cardiopulmonary exercise test (CPET-CL) with na interval of 48 h between tests. Spirometric measurements were obtained 5, 10, 15, 20 and 30 min after exercise; an FEV1 decline > 10% was considered EIB.
Results
Fifteen individuals had EIB in both tests [χ2 = 9.41; κ = 0.46 p < 0.002 (95% CI: 0.201-0.708)], with moderate agreement. There was a significant correlation between the greatest variation in the drop in FEV1 between the ISWT and the CPET-CL (r = 0.48; p < 0.01). There was a significant difference for ventilation maintenance time above 40% of Maximum Voluntary Ventilation between the groups of positive EIB (p = 0.001) and negative EIB (p = 0.001) and for ventilatory demand (positive EIB group) (p = 0.008) between ISWT vs CPET-CL. Moreover, assuming CPET-CL as the criterion test, ISWT presented a sensitivity of 62.5% and specificity was 100%.
Conclusion
ISWT showed moderate accuracy in detecting EIB in adults with asthma and was able to show similar metabolic and ventilatory demand presented in CPET-CL.
Acknowledgements
The authors would like to thank all the subjects who participated in this study and the financial support (FAPESP process n° 201123771–7) for the development of this project.
Authors contributions
Involvement in the conception, hypotheses delineation, and design of the study: IGL; VAPDL. Data acquisition: IGL, ASGA, FPGR. Data analysis and interpretation: IGL; ABS; VAPDL; JFA. Writing the article: IGL; VAPDL; ABS. Involvement in its revision prior to submission: IGL; ASGA; ABS; VAPDL. Approved the final version: IGL; ASGA; JFA; FPGR; ABS; VAPDL.
Institution where the study was performed
Universidade Federal de São Carlos, in São Carlos, São Paulo, Brazil.
Declaration of interest
The authors declare that there is no conflict of interest.