Our intervention for panic disorder, a combination of CBT and antianxiety medication delivered by a behavioral health specialist in liaison with PCPs and with the assistance of a psychiatric consultant, resulted in substantially better outcomes than did usual care. Significantly more subjects receiving the intervention had responded and remitted at each of the 4 assessment periods over the year, and changes in disability were also significant and persistent. The large effects on ASI scores are particularly noteworthy given that they are both reflective of recent panic and predictive of future symptom status.49,58
Even though reliance on a self-report measure of core cognitions associated with panic disorder is subject to responder biases, the longevity of observed effects on the ASI is unlikely to be fully attributable to such biases. The relatively robust intervention effects are also noteworthy given the high rate of depression in these subjects and the previously observed refractoriness to treatment of comorbid panic and depression.35
These results are more likely to be generalizable than a previous study of primary care panic disorder25
because they were observed across 3 distinct geographical sites, included a larger more ethnically heterogeneous group of primary care patients, required that patients pay for their medication, and used relatively inexperienced therapists and/or care managers to deliver CBT and coordinate medication management instead of highly trained expert psychiatrists.
The poor quality of care for primary care panic disorder observed in all subjects at baseline is consistent with the results of previously published studies in both panic disorder59
The intervention, contrary to expectation, did not result in superior provision of guideline-concordant pharmacotherapy, with rates increasing in both groups. Interestingly, this is consistent with recently published findings in primary care patients with depression.60
Reasons for this failure are unclear but are, according to our analyses, not a by-product of physicians of usual care patients implementing what they learned in the care of Collaborative Care for Anxiety and Panic study patients (ie, a spillover effect).61
It is possible that the non-medical background of the behavioral health specialist or the competing demands of both delivering CBT and trying to maximize medication use may have led to less than optimal focus on or achievement of quality medication. It is also possible that patients were less motivated to pay for and maximize their use of medications when CBT was already improving their symptoms and was being provided free of charge. Future interventions will need to explore these and other possibilities to develop solutions to improve the quality of pharmacotherapy provided to patients. The absence of an intervention effect on antianxiety pharmacotherapy quality, taken together with the substantial body of data supporting the efficacy of CBT in panic disorder as well as our data indicating a dose-response trend wherein more specialty visits with CBT components were associated with better outcomes, suggests that the improved outcomes for the intervention group may be attributed primarily to the CBT component of the intervention. Our findings stand in contrast to those of a recent review of “counseling” studies in primary care, which suggested that improvements with these mostly unstructured therapies were modest and only persisted in the short-term.62
The structured and skills-oriented nature of CBT may account for the greater longevity of our effects, consistent with results from many efficacy studies of CBT for panic disorder conducted in specialized clinical research settings,29,63
even though the CBT “dose” achieved in this effectiveness study was lower than in typical efficacy studies (eg, 72% of subjects completed the entire course of CBT in the Barlow et al29
efficacy study, while only about 40% of our subjects did). Notably, the reason for this discrepancy is because, unlike efficacy studies, we did not exclude patients who failed to attend a minimum number of sessions. Our results suggest that in a real-world setting serving primary care patients with multiple medical and psychiatric comorbidities, where treatment is less carefully controlled, CBT is still capable of exerting a significantly beneficial effect, although more work needs to be done to optimize adherence to the full course of treatment that produced optimal results. Our study was not intended, however, to test the effectiveness of CBT alone, and many patients were taking antianxiety medications, even if at less than optimal doses or durations. Thus, the outcomes achieved in this study cannot definitively be attributed to CBT alone. Nonetheless, the possibility that concomitant medication may not be necessary for some patients and that CBT alone tailored for the primary care setting might be an efficacious treatment for panic disorder should be systematically tested.
This study has a number of limitations. First, all care was delivered in university settings ostensibly limiting generalizability of both efficacy and cost estimates (though many of these settings served low-income, ethnically diverse, and disadvantaged populations). Second, CBT was provided free of charge, making it unlikely that this kind of program could be sustained and disseminated without added funds. Third, the multiple treatment elements make it impossible to determine the exact contribution of each element (ie, CBT and/or antianxiety pharmacotherapy). Fourth, master-level and/or newly graduated doctoral-level behavioral health specialists are not likely to be available to smaller primary care practices, although they are now being used by midsized community health practices through a program funded by the Bureau of Primary Care, Health Resources and Services Administration, Washington, DC. Furthermore, there is no reason to believe that nursing staff cannot be trained to implement the collaborative care model of treatment for anxiety disorders since this has been successfully done for depression.5
Although the aim of this study was to deliver and test a treatment for panic disorder, we learned that a narrow focus on this single disorder might be inadequate in the primary care setting. There were many patients (approximately 70%) with other anxiety disorders and/or major depression. These findings suggest a need to develop interventions that can better address the wide range of mood and anxiety disorders in these patients. We also learned that many patients did not adhere to the entire CBT program, even though it was brief and delivered with considerable flexibility of scheduling. This finding suggests the need for qualitative research to elucidate the reasons for nonadherence in these patients. A major goal of future work in this area should be to develop, implement, and disseminate approaches to treatment of anxiety disorders that are maximally acceptable to patients, physicians, and payers. The latter will be particularly important in ensuring the sustainability of such programs in the primary care setting.