Number of episodes in bipolar disorder: The case for more thoughtful conceptualization and measurement

Abstract

Objectives Number of mood episodes (NoE) may be an important prognostic indicator in bipolar disorder, with implications for treatment. However, NoE has been conceptualized and measured inconsistently throughout the literature. This review examines the construct of NoE in bipolar disorder, with the aim of enhancing its conceptualization and measurement. Methods A critical evaluation of literatures on important correlates of NoE, conceptually and phenomenologically overlapping features, and previous studies considering and measuring this construct was undertaken. Results The literature indicates that despite frequent use, NoE has been inconsistently defined and measured. Multiple studies have linked NoE with important clinical factors, including relapse, functioning, cognitive impairment and the effectiveness of both pharmacological and psychosocial interventions, yet conclusions are limited by its inconsistent treatment. Additionally, it seems evident that that NoE may best be treated as a fuzzy construct (rather than precise figure), with yet to be defined overlaps with clinical variables such as age at onset and severity. Attempts to measure this construct have varied in comprehensiveness and structure. Conclusions The NoE construct may have important implications for individuals with bipolar disorders. However, more consistent and systematic definition and assessment of NoE is required to advance this literature and clarify its role. Recommendations aimed at advancing the conceptualization and the measurement of NoE are provided. Conceptualization may be advanced by considering and exploring relationships between NoE and factors with which it overlaps, while measurement may best be improved with increased consistency and balancing accuracy with feasibility.

The 2020 Royal Australian and New Zealand College of Psychiatrists clinical practice guidelines for mood disorders

“…There is evidence that risk of recurrence increases with the number of prior episodes of bipolar disorder and a greater number of episodes is also associated with more chronic symptoms, and functional impairment (Tremain et al, 2020b). Number of episodes may also moderate the response to treatments, particularly adjunctive psychosocial treatments.…”

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

“…Increasing the understanding of the experiences of those within later stage is a step toward precision psychiatry. A benefit of this approach to adding granularity to staging over reliance on clinical history is avoiding validity and reliability concerns resulting from the recall and measurement‐related issues assessment of distal and often distressing events inherently involves 41 . Indeed, data about current symptoms, functioning, quality of life, and medication effectiveness are routinely collected as part of clinical assessment.…”

The influence of stage of illness on functional outcomes after psychological treatment in bipolar disorder: A systematic review

“…While no model of clinical staging in BD has been empirically validated, an International Society for Bipolar Disorders task force review concluded that there is sufficient evidence at this time supporting two stages of established BD, distinguishable based on number of episodes (NoE 11 ) and functioning. 12 The task force also proposed that such a dichotomization is likely to be of heuristic value in the treatment of BD, despite lack of validated boundaries or definitions at this time.…”

“…Most commonly, NoE has been used. [15][16][17][18][19] While a potentially useful and plausible proxy, 1 NoE alone cannot fully capture the complexity of the proposed staging phenomenon, 5,9,11 and in particular does not speak to the notion of disease extension. It has been proposed that analogues of physical disease progression in mental disorders may be functional impairment or disability, and cognitive functioning, 3,6,9,20 while proxies such as medical comorbidities and some psychiatric comorbidities better reflect disease extension.…”