Letter

In Reply: Dr. Kathol and Dr. Kishi raise an important, but fundamentally different, issue in asking whether the implementation of the MBHO in our case study led to an increase in total health care costs. Such an increase would clearly offset any gains from reductions in mental health treatment costs and would also imply poorer outcomes for patients with needs for mental health and substance abuse treatment. We more narrowly considered whether this particular MBHO shifted direct costs for such treatments—an important question in its own right. Several lines of evidence we presented in this and earlier publications suggest that this particular MBHO did not. Whether the implementation of the MBHO directly led to increases in other health care costs is a more difficult question to answer.

Others have tried to answer the question of whether increases in mental health and substance abuse treatment lead to corresponding decreases in other health care costs and vice versa. The idea of such a cost-offset effect is both seductive, for obvious reasons, and intuitive at some levels. Unfortunately, the evidence for it is much weaker than Kathol and Kishi imply. Although some studies do indeed show associations between mental health and other health care costs, these studies suffer from deep conceptual and empirical problems ( 1 ).

Kathol and Kishi also raise questions about our specific methods and findings regarding the narrower question of whether the MBHO shifted costs. The data set that we used is similar to almost all administrative and health claims data sets in that it did not allow us to identify who prescribed medications. The very fragmentation and lack of coordination of mental health and substance abuse treatment that concerns Kathol and Kishi—and us—also explains why there are so few studies of the cost-shifting behavior of MBHOs. We were quite fortunate to have access to all behavioral claims made under the MBHO, as well as to medical claims and to prescription drug claims from the third-party pharmacy benefit manager. In the absence of a direct link between prescriptions and prescribers, we view our test of whether there was an increase in use of psychotropic medications without concurrent use of specialty treatment as entirely reasonable.

We note that implementation of the MBHO took place during a period of rapid increases in prescribing by nonpsychiatrists and psychiatrists alike. In marked contrast to the MBHO experience in the study by Rosenheck and colleagues ( 2 ) that is cited by Kathol and Kishi, the number of people using outpatient specialty mental health and substance abuse treatment in our study also increased substantially with no change in treatment intensity ( 3 ).

Finally, Kathol and Kishi leap to much broader conclusions than we ourselves made. They state that we "suggested that the introduction of management practices via a managed behavioral health care organization (MBHO) does not shift 'treatment' costs" and that our "article gives the impression that carving out mental health and substance abuse treatment services from the rest of medical care is acceptable from a cost perspective." There is considerable variation in experience with MBHOs, and we described how the MBHO we studied might differ from others. We concluded that although in this case there was no evidence of cost-shifting, strong incentives remain for MBHOs to shift treatment costs.