Clinical and biochemical correlates of rapid cycling in bipolar disorder: A 20-year inpatient study

Background and objectives. Rapid cycling (RC) is a severe course specifier of bipolar disorder (BD), associated with worse clinical outcomes and increased treatment complexity. The objective of this study is to identify differences in clinical and biochemical parameters between bipolar patients with or without rapid cycling (RC). Methods. A total of 468 inpatients were included in the present study. Demographic, clinical and biochemical data, related to the first day of hospitalization, were obtained through a screening of the clinical charts and intranet hospital applications. The two groups identified by the lifetime presence of RC were compared by t tests for continuous variables and χ2 tests for qualitative ones; logistic regression models were subsequently performed. Results. Logistic regressions showed that patients with versus without RC: were more frequently hospitalized for a depressive episode (p < 0.01), had more previous psychiatric hospitalizations (p < 0.01), presented more often multiple medical comorbidity (p = 0.05) and seasonality (p = 0.02) as well as lower Global Assessment of Functioning (GAF) scores at the time of hospitalization (p = 0.02). RC patients also exhibited lower creatine phosphokinase (CPK) (p < 0.01) and neutrophil levels (p < 0.01). Conclusions. The presence of RC is important in designing a personalized treatment of bipolar patients as it is associated with (1) clinical variables of greater severity, (2) the tendency to a depressive profile and (3) multiple medical comorbidities. Further multi-center studies are needed to confirm the results of the present study in a framework of precision psychiatry.