Conceptualizing the later stage of bipolar disorder: Descriptive analyses from the ORBIT trial

This study aimed to investigate the features of later stage bipolar disorder (BD) and specifically, factors underlying later stage BD and potential subgroups within this stage, to understand more about the later stage group and contribute to the measurement of stage.

An exploratory factor analysis was conducted using variables relating to current phenomenological aspects of illness, followed by cluster analyses based on the identified factors. Finally, the resultant clusters were compared based on course of illness variables.

Fourteen extracted factors explained 57 percent of the variance. Latent structures aligned with current depressive symptoms, energy and interest, independence, occupational functioning, symptoms of anxiety, pain, elevated symptoms, interpersonal functioning, anger, perceptions of social connections, and perceptions of current medication effectiveness, cognitive issues, sleep issues, and sense of isolation. Two clusters were identified which differed significantly on each of these factors, and on a range of course of illness features including lifetime number of episodes, duration of illness and number of depressive hospitalizations.

Latent phenomenological features relevant to individuals in the later stage of BD were identified. Two clusters of individuals in later stage BD differ based on these features as well as course of illness, suggesting that there are distinct subgroups of individuals in the later stage of BD, distinguishable based on current phenomenology and illness history. However, findings are exploratory and therefore require confirmation before they can be applied clinically.