Improving retrospective ARDS case-finding using a simple 72-hour physiologic persistence rule
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Background
Retrospective studies frequently use single-time-point Berlin physiologic criteria (PaO2/FiO2 < 300 mm Hg plus positive end-expiratory pressure ≥ 5 cm H2O) to identify acute respiratory distress syndrome (ARDS). However, transient hypoxaemia is common among critically ill patients and often does not represent ARDS. Using these screens may overestimate ARDS prevalence and yield a cohort inconsistent with those seen in clinical trials.
We sought to determine whether a 72-h persistence criterion for hypoxaemia improves the accuracy of ARDS case identification and evaluate the additional case-finding value of radiology keyword searches and ICD-codes.
Methods
We conducted a retrospective cohort study using the MIMIC-IV database (2008–2019) for derivation and a UK ICU dataset (Imperial College Healthcare National Health Service Trust, 2009–2024) for external validation. All patients meeting Berlin physiologic criteria for at least 72 h were identified. From MIMIC-IV, we randomly selected 2000 patients who met 72-h persistence criteria for expert adjudication based on detailed review of clinical notes, imaging, and echocardiography, classifying them as ARDS, non-ARDS acute hypoxaemic respiratory failure, or possible ARDS. Sensitivity analyses with shorter durations (≥ 24 and ≥ 48 h) were performed. Diagnostic performance of radiology keyword searches and ARDS-specific ICD-9/10 codes were compared to expert adjudication.
Results
Of 18,621 patients who ever met physiologic criteria, 3940 met the 72-h persistence threshold. In a random sample of 2000 from this 72-h MIMIC-IV cohort, expert adjudication identified ARDS in 49.7% (95% CI, 48–52%); in the external UK validation cohort, 56% (95% CI, 46–66%) were adjudicated as ARDS. ARDS prevalence significantly declined with shorter persistence requirements: 21% after 48 h, 8% after 24 h, and 6% with single isolated measurements. Within the 72-h persistence criterion enriched sample, the highest performing radiology keyword search set provided limited sensitivity (49%) and moderate specificity (76%), whereas ICD codes had higher sensitivity (76%) but low specificity (47%).
Conclusions
Berlin physiologic criteria alone were inadequate for retrospective ARDS identification. A ≥ 72-h persistence rule improved cohort enrichment but did not define ARDS, with substantial residual misclassification remaining after physiologic screening. Persistence should therefore be viewed as a pragmatic enrichment strategy rather than a definitive retrospective ARDS label.
Retrospective studies frequently use single-time-point Berlin physiologic criteria (PaO2/FiO2 < 300 mm Hg plus positive end-expiratory pressure ≥ 5 cm H2O) to identify acute respiratory distress syndrome (ARDS). However, transient hypoxaemia is common among critically ill patients and often does not represent ARDS. Using these screens may overestimate ARDS prevalence and yield a cohort inconsistent with those seen in clinical trials.
We sought to determine whether a 72-h persistence criterion for hypoxaemia improves the accuracy of ARDS case identification and evaluate the additional case-finding value of radiology keyword searches and ICD-codes.
Methods
We conducted a retrospective cohort study using the MIMIC-IV database (2008–2019) for derivation and a UK ICU dataset (Imperial College Healthcare National Health Service Trust, 2009–2024) for external validation. All patients meeting Berlin physiologic criteria for at least 72 h were identified. From MIMIC-IV, we randomly selected 2000 patients who met 72-h persistence criteria for expert adjudication based on detailed review of clinical notes, imaging, and echocardiography, classifying them as ARDS, non-ARDS acute hypoxaemic respiratory failure, or possible ARDS. Sensitivity analyses with shorter durations (≥ 24 and ≥ 48 h) were performed. Diagnostic performance of radiology keyword searches and ARDS-specific ICD-9/10 codes were compared to expert adjudication.
Results
Of 18,621 patients who ever met physiologic criteria, 3940 met the 72-h persistence threshold. In a random sample of 2000 from this 72-h MIMIC-IV cohort, expert adjudication identified ARDS in 49.7% (95% CI, 48–52%); in the external UK validation cohort, 56% (95% CI, 46–66%) were adjudicated as ARDS. ARDS prevalence significantly declined with shorter persistence requirements: 21% after 48 h, 8% after 24 h, and 6% with single isolated measurements. Within the 72-h persistence criterion enriched sample, the highest performing radiology keyword search set provided limited sensitivity (49%) and moderate specificity (76%), whereas ICD codes had higher sensitivity (76%) but low specificity (47%).
Conclusions
Berlin physiologic criteria alone were inadequate for retrospective ARDS identification. A ≥ 72-h persistence rule improved cohort enrichment but did not define ARDS, with substantial residual misclassification remaining after physiologic screening. Persistence should therefore be viewed as a pragmatic enrichment strategy rather than a definitive retrospective ARDS label.
Date Issued
2026-12-01
Date Acceptance
2026-04-10
Citation
Intensive Care Medicine Experimental, 2026, 14 (1)
ISSN
2197-425X
Publisher
SpringerOpen
Journal / Book Title
Intensive Care Medicine Experimental
Volume
14
Issue
1
Copyright Statement
© The Author(s) 2026. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
License URL
Identifier
10.1186/s40635-026-00901-9
Subjects
Acute respiratory distress syndrome
Identification
Phenotyping
Case-finding
Persistence
Publication Status
Published
Article Number
ARTN 58
Date Publish Online
2026-04-30