The Consistency of Hypercapnic Respiratory Failure Case Definitions in Electronic Health Record Data

Area of Science:

• Pulmonary Medicine
• Critical Care Medicine
• Health Services Research

Background:

• Hypercapnic respiratory failure (HRF) presents a significant disease burden in emergency departments (EDs) and inpatient settings.
• Existing studies on HRF prevalence and burden utilize varying case definitions, raising concerns about consistency and validity.
• The lack of standardized case definitions hinders the interpretation and comparability of research findings on HRF.

Purpose of the Study:

• To assess whether diverse case definitions for HRF from health record-based studies identify similar patient cohorts.
• To evaluate the consistency and agreement among various HRF case definitions.
• To compare patient characteristics and outcomes across cohorts identified by different HRF definitions.

Main Methods:

• Identified 10 HRF case definitions from peer-reviewed literature.
• Constructed an emulation dataset from TriNetX (76 US hospitals) for adult ED and inpatient encounters in 2022.
• Applied case definitions to the emulation dataset, calculating Cohen's kappa (κ) for consistency and comparing patient cohorts.

Main Results:

• Case definitions demonstrated limited agreement (median κ = 0.35) in identifying HRF patients.
• Significant variations observed in demographic characteristics, comorbidities, and outcomes (ventilatory support, 30-day mortality) across cohorts.
• Diagnosis codes showed low sensitivity (23.5%) for detecting hypercapnia via arterial blood gas.

Conclusions:

• Current HRF case definitions identify patient groups with substantially different attributes and outcomes.
• This heterogeneity complicates the interpretation and generalizability of HRF research.
• Standardization of HRF case definitions is essential for enhancing research quality and comparability.