Modifiable and non-modifiable factors associated with functional impairment during the inter-episodic periods of bipolar disorder

The chronic, long-term evolution of bipolar disorder (BD) requires a careful clinical characterization with prognostic implications in terms of symptom and functional control. The OPTHYMUM multicenter study was conducted in France with the objective of evaluating residual symptoms on overall functioning of BD patients during inter-episodic period. The aims of the present study were to identify the potentially modifiable (e.g., treatable) and non-modifiable variables associated with functional impairment during the inter-episodic periods of BD. Sample was divided into two groups according to level of functioning (adequate vs. impaired), based on the FAST scale total score. FAST cut-off for functional impairment is a score >11. The two subgroups were compared as per sociodemographic and clinical variables with standard univariate analyses, and a logistic regression model was created. The model as a whole contained independent non-modifiable factors (age, gender, BD type, illness duration) and modifiable factors (illness severity, predominant polarity, depressive and manic residual symptoms, comorbidities). The final model was statistically significant (χ2 = 53.89, df = 5, p < 0.001). Modifiable factors most strongly associated with functional impairment were manic predominant polarity (OR = 1.79, CI 95% 1.09–2.96, p = 0.022), residual depressive symptoms (OR = 1.30, CI 95% 1.18–1.43, p < 0.001) and illness severity (OR = 1.24, CI 95% 1.01–1.52, p = 0.037), whilst non-modifiable factor was illness duration (OR = 1.03, CI 95% 1.01–1.05, p = 0.017). Despite intrinsic and non-modifiable illness characteristics, a clinical-wise choice of treatment may help to improve control of manic relapses. Potential improvement of residual depressive symptoms may alleviate the functional burden associated with bipolar disorder.