Reliability of circadian heart pattern analysis in psychiatry

The assessment of circadian heart patterns represents a new methodology for documenting physiological dysregulation associated with psychiatric illness. Previous research has demonstrated abnormal heart rate patterns, especially during the bedtime interval, that are associated with depression, generalized anxiety disorder, panic disorder, and schizophrenia. These patterns are derived from heart rate data obtained while wearing an unobtrusive, two-lead heart rate monitor over a 24-hour period. To establish basic reliability, the second author blindly rated heart-monitored data from 50 subjects on two occasions, separated by an average of 6.6 weeks (range = 2.9-15.7 weeks). Subjects were classified as "definitely psychiatric," "probably psychiatric," "borderline," "broadly normal," and "signature normal." The exact category agreement rate was 78%. If a one-category difference is permitted (e.g., "definitely psychiatric" and "probably psychiatric" counted as an agreement), the agreement rate was 92%. Circadian heart pattern analysis is a promising new technology in psychiatric research and warrants further investigation.