Factors influencing treatment outcome in bipolar disorder.

Sir,

We have read with great interest the paper titled, “Identification of factors affecting treatment outcome in bipolar disorder” by Vedanarayanan et al.[1] published recently in your journal. The article becomes timely when there is accruing research in the field of bipolar disorder (BD) course and outcome in our region.[23] Identification of factors influencing treatment outcomes is a step ahead in enhancing the recovery and functioning of a patient suffering from BD.

While the paper deserves merit for incorporating a longitudinal study design in analyzing factors influencing treatment outcome, certain aspects of the paper need to be analyzed critically to replicate and expand the current research. The authors have included BD patients of various types (BD-I, BD-II, with mixed features and cyclothymia), who were in clinical remission during enrolment into the study, and assessed the improvement in clinical symptoms after 6 months from the index visit. The authors' efforts in defining early onset and treatment delay in BD were quite informative in this paper. Although information on subtypes of BD was provided, systematic assessment of comorbid psychotic symptoms during the present mood episode and retrospective evaluation of psychiatric comorbidities seems lacking. Studies have shown that the BD tends to have frequent psychiatric comorbidities, especially anxiety disorders.[4] Mood episodes with psychotic symptoms and comorbid anxiety symptoms tend to influence poor outcomes in BD.[4] The authors have recorded the age at which BD was diagnosed albeit the age at onset (AAO) of the illness. Such data on the AAO of BD in the entire study sample (not restricted to early-onset cohort alone) would enable one to assess for the effect of AAO on treatment outcomes.

The clinical remission criteria as set by authors (Young Mania Rating Scale score [YMRS] <12) seems to be more inclusive than that recommended by the International Society for Bipolar Disorders Task Force Recommendations (YMRS <8 or <5). Hence, selection bias is quite possible. The authors have assessed for outcome after the end of the index episode. However, utilization of composite yet specific instruments such as the Clinical Global Impressions-bipolar would have ascertained the outcome for the entire illness duration and not restricting to one episode. Terms such as treatment noncompliance were assessed without definition or grades. Formats such as self-report scales and pill count are quite commonly used in BD research.[5]

Under results, though the factors such as early onset and treatment delay emerged as significant predictors of poor outcome in the study sample, their wide confidence intervals warrant further repetition to validate such claims. The authors have identified that remission rates are most frequent with one group of psychotropics (lithium salts, in this study). However, information on differential compliance rates across all the psychotropic classes (lithium salts, anticonvulsants, and antipsychotics) needs to be provided before arriving at such conclusions. The discussion on bidirectional link between BD and medical comorbidities, functional recovery of BD patients, genetic underpinnings (penetrance) in BD, and reasons for noncompliance seems detached from the context of the study's objectives and observed results.

The lines on how BD leads to mental retardation (in the “introduction” part) are bound to misguide the readership. The use of an older version of diagnostic statistical manual for mental disorders, the lack of systematic inclusion or exclusion of psychiatric comorbidities, especially anxiety disorders, and the lack of systematic assessment of drug compliance are some of the additional limitations of the paper. Nevertheless, the present study has paved a way for further research in unexplored areas such as outcome aspects of BD in India.

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Conflicts of interest

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