Pre‐diagnostic and post‐diagnostic psychopharmacological treatment of 16 288 patients with bipolar disorder

Objectives The aim was to describe the pre‐diagnostic and post‐diagnostic psychopharmacological treatment of bipolar disorder over the past two decades. Methods We identified all 16 288 individuals aged ≥ 18 years, who received their first diagnosis of bipolar disorder at a psychiatric hospital in Denmark between 1997 and 2014. For each calendar year, we calculated the proportion of patients (with index date in the respective calendar years) who were prescribed psychopharmacological treatment in the 2 years preceding and the 2 years following the date of the first diagnosis of bipolar disorder. For patients diagnosed with bipolar disorder from 2007 to 2010 (n = 3949), we described the psychopharmacological treatment from 1995 to 2016, that is, from up to 16 years prior to and up to 10 years after the diagnosis. Results Concomitant use of ≥ 2 antidepressants in the 2 years preceding the bipolar disorder diagnosis increased over the study period. In the 2 years following the diagnosis, the use of lithium decreased, while use of atypical antipsychotics (particularly quetiapine), valproate, and lamotrigine increased over the study period. During the 10 years following the diagnosis, 53%‐90% of the patients received any psychotropic drug while 12%‐26% received treatment with an antidepressant without overlapping treatment with a mood‐stabilizing drug. Conclusion The increased use of two or more antidepressants suggests more focus on bipolar disorder as a differential diagnosis to treatment‐resistant unipolar depression. The decreased use of lithium (consistent with international trends) and the prevalent use of antidepressants without overlapping treatment with a drug with mood‐stabilizing properties are concerning.