Lower use of augmentation therapy among patients with depression related to higher cost sharing, study demonstrates

Higher cost sharing appears to be associated with lower rates of utilization of classes of drugs used to augment antidepressant therapy among commercially insured adults with depression, according to data from a new study. The study authors noted that some patients with depression do not respond to first-line antidepressant therapy and require augmentations with another treatment, such as a second antidepressant, a stimulant, a mood stabilizer or a second-generation antipsychotic (SGA)....

Higher cost sharing appears to be associated with lower rates of utilization of classes of drugs used to augment antidepressant therapy among commercially insured adults with depression, according to data from a new study.

The study authors noted that some patients with depression do not respond to first-line antidepressant therapy and require augmentations with another treatment, such as a second antidepressant, a stimulant, a mood stabilizer or a second-generation antipsychotic (SGA).

In order to examine the relationship between patient cost sharing and the use of augmentation among commercially insured patients with depression, they performed a retrospective observational study using data from the Thomson Reuters MarketScan Commercial Claims and Encounters database.

The study included 48,807 patients aged 18 to 64 years who had a first antidepressant claim between Jan. 1, 2005, and Dec. 31, 2008, and at least two medical claims with a diagnosis of depression. To allow for partial response, augmentation was required to be at least four months after the initial antidepressant. The index date was the date four months after the initial antidepressant; follow-up was at least 52 weeks following the index date.

Overall, 10.2 percent (n=4,984) of the participants augmented therapy within one year of the index date. Most augmented with an antidepressant (n=3,791), followed by a mood stabilizer (n=627), SGA (n=292) and a stimulant (n=274).

The mean cost-sharing index varied by drug class, with the smallest cost-sharing amount for antidepressants ($27.05 per fill) and the highest amount for SGAs ($38.81 per fill). The cost-sharing index for all classes combined was $28.67 per fill, on a weighted average.

A logistic regression analysis used to model the odds of any augmentation during the one-year period after the index date showed that as the cost-sharing index increased, the likelihood of any augmentation decreased. A $10 higher cost-sharing index for all augmentation classes was associated with a statistically significant 15 percent lower odds of augmentation.

In addition, a $10 higher cost-sharing index was associated with a significant 1.5 percentage point lower probability of any augmentation. Therefore, the $10 higher cost-sharing index was associated with a 44 percent smaller share of patients using augmentation therapy.

An alternative-specific conditional logit model of augmentation class also revealed that higher cost sharing was associated with a significant 15 percent lower odds of augmentation.

Specifically, a doubling in the price of antidepressant augmentation was associated with a 41 percent smaller share of patients using antidepressants as augmentation. Further, a doubling in the price of SGAs was associated with a 63 percent smaller share of patients using SGAs for augmentation, while a doubling in the prices of mood stabilizers and stimulants was associated with 49 percent smaller and 55 percent smaller, respectively, shares of patients using these drugs as augmentation.

"The economic burden of depression is considerable in terms of direct medical and indirect absence and disability costs, and in lost productivity time," the authors wrote. "As such, employers and payers may want to encourage improvements to treatment of enrollees with depression, including first-line and augmentation therapies."

The study was published as a Web exclusive by The American Journal of Managed Care.

This research was funded by Bristol-Myers Squibb Co. and Otsuka Pharmaceutical Co. Ltd. These firms market Abilify (aripiprazole), which is indicated for use as add-on treatment to an antidepressant for adults with major depressive disorder who have not responded adequately to antidepressant therapy. The drug is also approved for the treatment of manic and mixed episodes associated with bipolar I disorder in adults and pediatric patients aged 10 to 17 years, for the maintenance treatment of bipolar I disorder as adjunctive therapy to the mood stabilizers lithium and valproate, for the treatment of schizophrenia in adults and adolescents aged 13 to 17 years and for the treatment of irritability associated with autistic disorder in pediatric patients aged 6 to 17 years.