Therapeutic drug monitoring of mood stabilizers in Medicaid patients with bipolar disorder

Objective: The authors' goal was to determine the extent and pattern of blo od serum monitoring of mood stabilizers in Medicaid patients with bipolar d isorder. Method: Data were drawn from a Medicaid medical claims data set fr om Pittsburgh and the surrounding region. The authors identified bipolar pa tients using lithium, valproate, and carbamazepine (N=718) and then examine d the patient demographic, diagnostic, and service use variables associated with therapeutic drug monitoring. Results: A substantial proportion of lit hium users (36.5%), valproate users (42.4%), and carbamazepine users (42.2% ) with bipolar disorder diagnoses did not receive therapeutic drug level te sting during the 12-month study period. Carbamazepine users who were male o r in the 30-49-year age range were significantly less likely to be tested f or serum drug level. Lithium users who did not receive partial-hospitalizat ion psychiatric services and valproate users who received mental health cas e management were also less likely to be tested for serum drug level, Over one-half of the lithium users (54.1%) did not receive thyroid function test s, and few (4.2%) received renal function tests. Patients who did receive t ests for serum drug level were likely to receive the other recommended test s. Conclusions: Many Medicaid patients with bipolar disorder received no th erapeutic drug monitoring. Patient sociodemographic characteristics contrib uted little to explaining this omission, although some types of service uti lization were related to rates of serum drug level testing.