a. Use and Continuity of Medications
Most beneficiaries with schizophrenia or bipolar disorder had at least one claim for an evidence-based medication in 2007. Ninety-two percent of beneficiaries with schizophrenia and 87 percent with bipolar disorder had at least one claim for an evidence-based medication. However, beneficiaries often failed to receive continuous medications. Among beneficiaries who received evidence-based medications, 64 percent of those with schizophrenia and 54 percent of those with bipolar disorder had a supply of evidence-based medications for at least 80 percent of the days enrolled in Medicaid following receipt of the first evidence-based medication (referred to hereafter as high medication continuity).
b. Depot Antipsychotics
While depot or injection antipsychotics are not necessarily considered to have a stronger evidence base than oral antipsychotics, some clinicians encourage the use of depot antipsychotics for individuals who have difficulty maintaining the use of oral antipsychotics (Kane 2011). Thus, we investigated the extent to which beneficiaries received depot antipsychotics and whether their use was associated with better medication continuity. Across all states in the study, only 10 percent (n=10,084) of beneficiaries with schizophrenia and 2 percent (n=884) with bipolar disorder received depot antipsychotics. Beneficiaries who received depot antipsychotics did not consistently have higher rates of medication continuity; in some states, continuity was higher among beneficiaries who received depot antipsychotics, while in others, continuity was lower among this group. These findings should be interpreted with caution, given the relatively small number of beneficiaries who received depot antipsychotics. In addition, the benefit of depot antipsychotics with respect to continuity may be observable beyond one year of data, or among different subpopulations.
c. Antidepressants for Bipolar Disorder
Bipolar disorder can be treated with a combination of medications that include mood stabilizers (lithium and anticonvulsants), antipsychotics, and antidepressants. The efficacy and safety of antidepressants in the absence of mood stabilizers or antipsychotics in the treatment of bipolar disorder remains controversial. This is because there is some evidence that the use of antidepressants alone may exacerbate mood swings. Across states, among beneficiaries with bipolar disorder who used an antidepressant continuously for at least 3 months, only 7 percent went 60 days or more without filling a concurrent prescription for lithium, valproate, carbamazepine, lamotrigine, or an antipsychotic.