Predictors of recurrence during long-term treatment of bipolar I and II disorders. A 4 year prospective naturalistic study.

Background: Despite the large number of treatments available for bipolar disorder (BD), more than one half of patients have a recurrence within 2 years, and over 90% experience at least one additional affective episode during their lifetime.

Methods: The aim of this study was to test the impact of a number of demographic and clinical features on the risk to recurrence in a real- word representative sample of 266 outpatients with BD-I or II treated in a naturalistic setting during a 4-years-follow-up period.

Results: We found that the number of episodes per year after study entry, compared to the number of episodes per year before study entry,significantly decreased and that about one third of patients had no recurrences during the observation period. The length of follow-up and the number of previous episodes, mainly depressive, predicted the risk of recurrence, while female gender, higher age at intake, and a higher frequency of past mixed episodes predicted a higher frequency of recurrences.

Limitations: The study had some limitations to consider: i.e. the risk of poor reliability of information on the previous course of illness or the naturalistic treatment during the follow-up.

Conclusions: Our study suggests that (a) an evidence-based long-term treatment, with regular follow-up visits could improve the course of disease and prognosis; (b) clinicians should carefully consider the presence of a high number of mixed episodes, to provide more targeted treatment strategies; (c) an appropriate use of antidepressants in selected patients did not worsen the course of illness.