Self-reported data from patients with bipolar disorder: impact on minimum episode length for hypomania

Michael Bauer, Charite University Medicine Berlin
Paul Grof, Mood Disorders Clinic of Ottawa
Natalie L. Rasgon, Stanford University School of Medicine
Wendy K. Marsh, University of Massachusetts Medical School
Rodrigo A. Munoz, University of California San Diego
Kemal Sagduyu, University of Missouri Kansas City School of Medicine
Martin Alda, McGill University
Danilo Quiroz, Clinicas PsicoMedica Research Group
Tasha Glenn, ChronoRecord Association Inc.
Christopher Baethge, University of Cologne
Peter C. Whybrow, University of California Los Angeles

At the time of publication, Wendy Marsh was not yet affiliated with the University of Massachusetts Medical School.


OBJECTIVE: Some investigators have suggested decreasing the minimum hypomania episode length criterion from 4 days, as in the DSM-IV, to 2 days. Using daily self-reported mood ratings, we studied the impact of changing the length requirement on the number of hypomanic episodes in patients with bipolar disorder.

METHOD: 203 patients (135 bipolar I and 68 bipolar II by DSM-IV criteria) recorded mood daily using ChronoRecord software (30,348 total days, mean 150 days). Episodes of hypomania and days of hypomania outside of episodes were determined.

RESULTS: Decreasing the minimum duration criterion for an episode of hypomania from 4 to 2 days doubled the mean percent of days in a hypomanic episode for each patient (4% to 8%), doubled the number of patients with a hypomanic episode (44 to 96) and increased the number of hypomanic episodes for all patients about three-fold (129 to 404). With a minimum episode length of 4 days, bipolar I patients were more likely to report hypomania outside episodes than bipolar II patients (p=0.010), but with a length of 2 or 3 days there was no significant difference in the distribution of hypomania outside of episodes by diagnosis. With a 2-day length, about one-third (36%) of hypomania remained outside of an episode.

LIMITATIONS: Self-reported data, computer access, relatively short length, fewer bipolar II than bipolar I patients.

CONCLUSION: As the minimum length for an episode of hypomania decreases, there was a large increase in both the number of episodes and number of patients with episodes. One-day hypomania outside of episodes occurs frequently in both bipolar I and bipolar II disorder.