Exploring the role of cold air in airway hyperresponsiveness and asthma diagnostic testing: a systematic review and meta-analysis
Clinical Snapshot
PICO Framework
| P — Population | Patients with asthma and exercise-induced bronchoconstriction, compared to healthy controls |
| I — Intervention | Cold air bronchial challenge test (CACh) |
| C — Comparator | Healthy controls and reference standard asthma diagnostic tests |
| O — Outcomes | Diagnostic accuracy (sensitivity and specificity), FEV1 reduction ≥10%, weighted mean difference in FEV1 decrease |
Bottom Line
This systematic review of 39 studies suggests cold air challenge testing has high specificity (95.9%) and moderate sensitivity (80.8%) for asthma diagnosis using a ≥10% FEV1 decrease threshold. However, extremely high heterogeneity (I²=99%) between studies, primarily due to varying reference standards for asthma diagnosis, significantly limits confidence in pooled estimates. While the test shows promise as a diagnostic tool, particularly given its high specificity reducing false positives, the substantial between-study variation and authors' conclusion that 'further research is needed' suggests premature implementation in routine practice. The test may have utility in specialized respiratory units where standardized protocols can be established, but current evidence is insufficient to recommend widespread adoption. Clinicians should await higher-quality studies with standardized reference standards before incorporating cold air challenge into routine asthma diagnostic pathways.
Key Findings
P Value: p<0.001 for weighted mean difference after trim-and-fill
Effect Size: Sensitivity 0.808, Specificity 0.959 for ≥10% FEV1 decrease
Primary Outcome: Diagnostic accuracy of cold air challenge test for asthma diagnosis
Nnt Or Sensitivity: Sensitivity 80.8%, Specificity 95.9%, Positive predictive value and negative predictive value not reported
Confidence Interval: Not reported in abstract
Clinical Application
Cold air challenge may be more accessible than exercise testing in some settings, though requires specialized equipment and trained personnel Could complement current RACGP asthma diagnostic guidelines, particularly where exercise testing unavailable. TGA-approved spirometry equipment required. May reduce diagnostic uncertainty in borderline cases. Patients with suspected asthma or exercise-induced bronchoconstriction requiring objective diagnostic testing
Abstract
BACKGROUND: Asthma is a heterogeneous disease, making uniform diagnosis challenging, resulting in both under- and overdiagnosis. We conducted a systematic review and meta-analysis to summarise the data on diagnostic accuracy of a cold air bronchial challenge test (CACh) in exercise-induced bronchoconstriction and asthma. METHODS: Databases (PubMed, Embase, Web of Science core collection, Cochrane Library and the Cumulative Index to Nursing and Allied Health Literature via EBSCO) were systematically screened for articles evaluating the use of CACh as a diagnostic tool in exercise-induced bronchoconstriction and asthma. A random-effects model was used to calculate the effect on the reduction in forced expiratory volume in 1 s (FEV1) by CACh in healthy controls compared to patients with asthma. Risk of bias was evaluated using the Quality Assessment of Diagnostic Accuracy Studies-Comparative. This study is registered with PROSPERO (www.crd.york.ac.uk/PROSPERO/ identifier number CRD42021290350). RESULTS: After screening and removal of duplicates, 39 studies were included. Aggregate sensitivity and specificity of a FEV1 decrease ≥10% after CACh were 0.808 and 0.959, respectively. The weighted mean difference in percentage FEV1 decrease after CACh for patients with asthma compared to healthy controls was -17.58. High heterogeneity (I2=99) was mainly explained by differences in reference tests to diagnose asthma. Application of the trim-and-fill method to account for publication bias imputed eight studies, resulting in a notable reduction in heterogeneity. The overall effect (a significant decrease in FEV1 in patients with asthma) remained statistically significant (-8.18, p<0.001). CONCLUSION: Our study shows the high sensitivity and specificity and possible clinical implications of a CACh in the diagnosis of asthma. Further research is needed to confirm this.
References
- 1.Marain, N. F., Claus, R., Colemont, M., Ronsmans, S., Janssen, L., Vanoirbeek, J., Bullens, D., & Dupont, L. (2026). Exploring the role of cold air in airway hyperresponsiveness and asthma diagnostic testing: a systematic review and meta-analysis. European Respiratory Review, 35(160). https://doi.org/10.1183/16000617.0205-2025
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