Twenty-year medication use trends in first-episode bipolar disorder

To study the medication use patterns in patients newly diagnosed with bipolar disorder (BD) in Finland during the past 20 years.

All persons diagnosed with BD between 1996 and 2018, aged 16-65 years, with no previous BD diagnosis were identified from nationwide Finnish registers (N = 26,395). The point prevalences of medication use were observed up until 5 years after the first diagnosis. Five sub-cohorts according to calendar year of first diagnosis were also formed and the prevalence of medication use was compared between sub-cohorts 3 months after diagnosis. Medication data were modeled with the PRE2DUP-method using dispensing data.

The prevalence of overall medication use declined during the 5-year follow-up period in the total cohort. The highest prevalence of use was seen 3 months after diagnosis for the three main medication classes-antidepressants (40.8%), antipsychotics (30.8%) and mood stabilizers (29.2%). The prevalence of lithium use varied between 5.9% and 6.5% during the 5 years in the total cohort, and the lowest prevalence of use at 3 months was seen in sub-cohort diagnosed in 2016-2018 (4.1%) versus 12.1% in 1996-2000 sub-cohort. The prevalence of benzodiazepine use was between 12.4% and 13.5% and the prevalence of Z-drugs was between 7.3% and 7.9% during the 5 years. The prevalence of long-acting injectable antipsychotic (LAI) use was the highest in patients diagnosed in 2016-2018, although still only 0.8%.

(i) The use of antidepressants is too prevalent, (ii) the use of lithium is declining and needs to be increased, and (iii) LAIs are markedly underutilized as compared to their oral counterparts.