Socio-demographic and clinical characterization of patients with Bipolar Disorder I vs II: a Nationwide Italian Study

Bipolar disorders (BDs) are prevalent, comorbid and disabling conditions, associated with the highest suicide risk among psychiatric illnesses. In the last few years, new efforts to better characterize the socio-demographic and clinical profiles of BD type I vs II have been documented by several reports, with novel and insightful findings in the field. The present multicenter study aimed to provide a comprehensive and reliable representation of the Italian reality, through the analysis of the largest national sample of bipolar patients collected so far. A total of 1500 patients (BD I n = 963 and BD II n = 537) from different psychiatric departments, participating in the Italian Chapter of the “International Society of Bipolar Disorders” (ISBD), were assessed and divided into two groups on the basis of their diagnostic subtype, and different socio-demographic and clinical variables were compared between the two subgroups. Chi-squared tests for categorical variables and t tests for continuous variables were performed for group comparison. Furthermore, a multivariable logistic regression was performed, considering diagnostic bipolar subtype (type I or II) as dependent variable, and socio-demographic/clinical characteristics as independent variables. BD I vs II patients showed an overall less favorable socio-demographic and clinical profile. In addition, the multivariable logistic regression showed that BD II vs BD I was predicted by the absence of lifetime suicide attempts (OR = 1.58, p = 0.01), a later age of diagnosis (OR = 1.03, p < 0.01), less hypomanic episodes in the last year (OR = 2.29, p < 0.0001) and absence of psycho-educational interventions in the last year (OR = 0.51, p < 0.01). BD I and II patients were found to significantly differ in relation to specific clinical variables, which should be considered within updated diagnostic–therapeutic algorithms.