Trends in prescriptions of lithium and other medications for patients with bipolar disorder in office-based practices in the United States: 1996–2015

Background: Studies have shown that rates of lithium use for bipolar disorder in the United States declined through the 1990s as other mood stabilizing anticonvulsants and second-generation antipsychotics (SGAs) became more popular. We examined trends of medications for bipolar disorder from 1996 to 2015. Methods: Twenty years of data from the National Ambulatory Medical Care Survey (NAMCS) were used. Weighted percentages of reported use of lithium, anticonvulsants, SGAs and antidepressants were calculated over two-year intervals. Logistic regression was used to examine factors related to polytherapy. Results: Reported use of lithium declined from 38.1% (95%CI: 29.8% - 46.3%) in 1996–97 to 14.3% (95%CI: 10.6% - 18.1%) in 2006–07 and has remained stable since. During this time, reports of SGAs more than doubled. SGAs and/or anticonvulsants were reported in 75.4% (95%CI: 69.5% - 81.3%) of visits with bipolar diagnoses in 2014–15. Polytherapy increased by approximately 3% every two years and in 2014–15 occurred in over 30% of visits. Antidepressants were reported in 40–50% of visits, but their reported use without other mood stabilizers decreased from 18.2% (95%CI: 11.7% - 24.8%) in 1998–99 to 7.5% (95%CI: 4.2% - 10.9%) in 2014–15. Limitations: The sample had limited power to study the effect of individual medications or the potential for differing effects in certain sub-groups of patients. Conclusions: This study further documents the declining use of lithium for bipolar disorder, and corresponding increase in use of anticonvulsants and SGAs, despite the fact that lithium is typically recommended as a first line therapy for bipolar disorder.