Changes in prescribing for bipolar disorder between 2009 and 2016: national-level data linkage study in Scotland

Abstract

BackgroundPeople with bipolar disorder typically require long-term pharmacological treatment to prevent episodes of depression or mania. However, evidence-based guidelines are often not followed by prescribers and, in some countries, prescribing of lithium is in decline. Polypharmacy is also common in bipolar disorder.AimsTo employ a data linkage approach to describe and evaluate prescribing patterns in bipolar disorder in Scotland between 2009 and 2016.MethodBy linking prescribing data to the electronic Scottish Morbidity Records, we identified a cohort of 23 135 patients with bipolar disorder who were prescribed psychotropic medication between 2009 and 2016. We examined trends in proportions of patients prescribed each of six drug categories. Random effects logistic models examined change in prescribing over years of interest.ResultsThe most common form of treatment was antidepressant monotherapy (24.96%), with only 5.90% of patients receiving lithium monotherapy. Prescribing of antipsychotics and anti-epileptics increased from 2009 to 2016 (antipsychotics: odds ratio 1.16, 95% CI 1.15–1.18; anti-epileptics: odds ratio 1.34, 95% CI 1.32–1.36), whereas prescribing of lithium decreased (odds ratio 0.83, 95% CI 0.82–0.85). Prescribing of valproate decreased from 2009–2016 in women, but increased in men (women: odds ratio 0.93, 95% CI 0.90–0.97; men: odds ratio 1.11, 95% CI 1.04–1.18).ConclusionsAntidepressant monotherapy was the most common form of treatment for bipolar disorder in Scotland and prescribing of lithium has declined between 2009 and 2016. The findings are concerning and represent a gap between treatment guidelines and clinical practice.Declaration of interestNone.