Prescribing patterns for older-age bipolar disorder patients discharged from two public mental hospitals in Taiwan, 2006-2019.

Background: Older-age bipolar disorder (OABD) is commonly defined as bipolar disorder in individuals aged 60 or more. There have been no studies to examine temporal trends in the pharmacological treatment of OABD. We aimed to investigate prescription changes among OABD patients discharged from two public mental hospitals in Taiwan from 2006 to 2019.

Methods: OABD patients discharged from the two study hospitals, from 1 January 2006 to 31 December 2019 (n = 1072), entered the analysis. Prescribed drugs at discharge, including mood stabilisers (i.e., lithium, valproate, carbamazepine, and lamotrigine), antipsychotics (i.e., second- and first-generation antipsychotics (SGAs and FGAs)), and antidepressants, were investigated. Complex polypharmacy was defined as the use of three or more agents among the prescribed drugs. Temporal trends of each prescribing pattern were analyzed using the Cochran-Armitage Trend test.

Results: The most commonly prescribed drugs were SGAs (72.0%), followed by valproate (48.4%) and antidepressants (21.7%). The prescription rates of SGAs, antidepressants, antidepressants without mood stabilisers, and complex polypharmacy significantly increased over time, whereas the prescription rates of mood stabilisers, lithium, FGAs, and antidepressants plus mood stabilisers significantly decreased.

Conclusions: Prescribing patterns changed remarkably for OABD patients over a 14-year period. The decreased use of lithium and increased use of antidepressants did not reflect bipolar treatment guidelines. Future research should examine whether such prescribing patterns are associated with adverse clinical outcomes.