Patient Considerations and ATS-ERS PFT Acceptability Criteria
This article was produced by Vitalograph’s Grant Sowman, VP of Clinical Services and Respiratory Physiologist, in collaboration with the Vitalograph Clinical Trials Insights Team.
As Pulmonary Function Testing (PFT) continues to serve as a critical component in clinical trials the challenge of applying standardised quality criteria across diverse patient populations has come into sharper focus. In this recent webinar, we explored Vitalograph’s real-world PFT data to better understand failure patterns and how bespoke, patient-specific QC approaches might deliver more accurate and useful data in clinical trials.
Quality Criteria— Essential but not Absolute
ATS/ERS guidelines and associated benchmark criteria remain central to maintaining data integrity in PFT. However, these standards are not intended to be one-size-fits-all. Particularly in clinical research settings, we must consider the real-world limitations and physiological differences across patient populations.
As highlighted in the session: "There are benchmark criteria... but we need to consider adapting them per your patient population." For example, some patients may be unable to meet the forced expiratory volume (FEV₁) or forced vital capacity (FVC) standards due to disease severity, fatigue, or other limitations—not poor effort or training [1].
Tailored Approaches by Indication
One of the most thought-provoking points came from the analysis of failed spirometry sessions. These insights suggest a significant variation in test failure causes by condition type.
For example, patients with muco-obstructive diseases such as Primary Ciliary Dyskinesia may show artificially low FEV₁ in initial tests due to mucus mobilisation. Rather than discarding early results outright, Grant proposed increasing the number of manoeuvres—e.g., requiring five instead of the standard three—to ensure reliable repeatability later in the session.
"Rather than ignoring the first two [tests], do more testing... so you can use later tests for repeatability."
This adaptive approach highlights the need for flexibility in protocol design, allowing for more inclusive and representative data sets across different disease states [2].
Session vs. Manoeuvre-Level Challenges
While much attention is placed on overall session success, the webinar raised important questions around manoeuvre-level acceptability—especially in patients with obstructive, restrictive, or mixed lung patterns.
Currently, anecdotal data suggest that patients with restrictive diseases such as idiopathic pulmonary fibrosis (IPF) may struggle with the start of test due to delayed inspiratory efforts. In contrast, obstructive conditions like COPD might show poor expiratory effort or premature termination.
"Even the smallest hesitation can cause a failed start, but the overall FVC and FEV₁ might still be valid."
These nuances underscore the need for further data analysis and indicate a future direction in research that could refine our interpretation of manoeuvre-level data per condition [3].
The Role of FIVC and Newer Parameters
Introduced in the 2019 ATS/ERS spirometry standards, Forced Inspiratory Vital Capacity (FIVC) is an increasingly important quality indicator. It helps verify that a true maximal inhalation preceded the forced exhalation—critical for ensuring FVC and FEV₁ validity.
"If FIVC is greater than FVC, that could suggest the patient didn’t inhale fully before exhalation, potentially underestimating key values."
Despite its importance, data on FIVC performance across patient groups remain limited, and further investigation is warranted to understand its clinical utility in both QC and endpoint interpretation [1][4].
Adapting to Unique Patient Needs
One of the most practical discussions addressed IPF patients and the glottic notch—a closure of the vocal cords during forced expiration that can create artefacts.
Should patients showing this pattern be excluded? Not necessarily.
"If the pattern is consistent and FVC is repeatable, it may still be usable—pending confirmation with medical monitors and study leads."
This represents a broader call for protocol flexibility, where repeatable but atypical test shapes may still yield valuable clinical data when judged within a patient-specific context [5].
Visual Cues and Tidal Breathing
The conversation also touched on tidal breathing prior to forced manoeuvres. While not always mandatory, including it on the flow-volume loop can help visually confirm test quality and consistency across trials.
"Having that tidal loop on your graph helps visually check pre-test effort and deep inhalation."
Incorporating these visual indicators can be especially helpful in multicentre trials where centralised overreading is applied, and rapid interpretation is required [6].
Conclusion: From Standardisation to Personalisation
This webinar marked an important shift in spirometry QC discourse—from rigid standardisation to nuanced, patient-centred adaptation. While standard guidelines remain vital, integrating data-driven flexibility could enhance both data quality and trial inclusivity.
“Having a better understanding of what your patient might struggle with gives us leeway to apply QC that’s both patient-specific and high quality.”
As spirometry continues to evolve, so must our criteria for evaluating its success—balancing rigour with real-world variability to ensure the most accurate representation of lung function in clinical research.
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References
Graham BL, Steenbruggen I, Miller MR, et al. Standardization of Spirometry 2019 Update: An Official American Thoracic Society and European Respiratory Society Technical Statement. Am J Respir Crit Care Med. 2019;200(8):e70–e88. https://doi.org/10.1164/rccm.201908-1590ST
Mahler DA, Waterman LA, Ward J, et al. Failure of clinical trial participants with COPD to meet spirometry quality standards: causes and solutions. COPD. 2014;11(6):603–610. https://doi.org/10.3109/15412555.2014.922066
Nathan SD, Barbera JA, Gaine SP, et al. Pulmonary hypertension in chronic lung disease and hypoxia. Eur Respir J. 2019;53(1):1801914. https://doi.org/10.1183/13993003.01914-2018
Miller MR, Hankinson J, Brusasco V, et al. Standardisation of spirometry. Eur Respir J. 2005;26(2):319–338. https://doi.org/10.1183/09031936.05.00034805
Mooney JJ, Elicker BM, Petersen H, et al. Glottic closure and its effects on spirometry in IPF patients. Chest. 2016;150(4):921–928. https://doi.org/10.1016/j.chest.2016.04.015
Haynes JM. Accuracy and repeatability of spirometry in a community setting: The need for quality monitoring. Respir Care. 2012;57(5):798–802. https://doi.org/10.4187/respcare.01382