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The 35% CO2 challenge in panic disorder: optimization by receiver operating characteristic (ROC) analysis
1Department of Neuropsychiatric Sciences, University of Milan School of Medicine, S. Raffaele Hospital IRCCS, Italy.
Journal of Psychiatric Research
|March 1, 1995
Summary
The 35% CO2 challenge effectively identifies panic disorder (PD) patients, with specific anxiety increments accurately distinguishing them from controls. This test offers a reliable method for diagnosing panic disorder.
Area of Science:
- Psychiatry and Psychology
- Clinical Neuroscience
- Medical Diagnostics
Background:
- Panic disorder (PD) diagnosis relies on symptom identification, but objective biological markers are sought.
- Carbon dioxide (CO2) inhalation is a known panicogen, potentially useful for diagnostic challenges.
Purpose of the Study:
- To evaluate the efficacy of a 35% CO2 gas mixture as a diagnostic challenge for panic disorder.
- To establish an optimal threshold for differentiating panic disorder patients from healthy controls using ROC analysis.
Main Methods:
- Receiver operating characteristic (ROC) analysis was employed.
- 91 outpatients diagnosed with panic disorder and 46 healthy controls inhaled a 35% CO2/65% O2 gas mixture.
- Subjective anxiety levels were measured post-inhalation to determine discriminatory power.
Main Results:
- ROC analysis demonstrated the CO2 challenge's ability to discriminate between PD patients and controls.
- An 86% probability of correct classification was achieved based on post-challenge subjective anxiety.
- An absolute increment of 20 units or a 26% relative increment in subjective anxiety served as the ideal discrimination threshold.
Conclusions:
- The 35% CO2 inhalation test is a potent tool for discriminating panic disorder patients from controls.
- The identified anxiety increment thresholds provide a validated method for diagnostic support in panic disorder.