Considering the costs of bipolar depression: more research is needed on the impact of untreated bipolar depression on society.
Many employers have responded to this situation by expanding depression outreach, treatment, and disease management programs. This has occurred at a time when many other factors have led to an increase in the proportion of workers with depression who have received treatment:
* the introduction and aggressive promotion of direct-to-consumer advertising of new psychotropic medications with improved side-effect profiles (2);
* the development of new community programs aimed at promoting awareness, screening, and help seeking for mental disorders (3); and
* the expansion of primary care, managed care, and behavioral carve-out systems to deliver mental health services. (4)
These efforts collectively led to more than a tripling of the number of people who annually receive healthcare for depression in the United States in recent years compared with the late 1980s. (5)
The increased treatment of depression is encouraging in many ways. However, it also creates a major challenge for behavioral healthcare providers that must be recognized and met aggressively: that a much higher proportion of people with depression than previously realized suffer from an undetected and untreated bipolar spectrum disorder. (6)
Although bipolar disorder traditionally has been thought to have a lifetime prevalence of only about 1% in the general population, (7,8) clinical and epidemiologic studies are leading to a substantial upward revision of this estimate. This revision is based on mounting evidence for the existence of a broad bipolar spectrum that includes not only hypomania, but also subthreshold manic symptoms and medication-induced manic symptoms. (9-11) Although research is still incomplete, the available evidence suggests that this bipolar spectrum might characterize as much as 5 to 8% of the general population and, importantly, include a substantial proportion of the people who experience depressive episodes. (6)
The available evidence makes it quite clear that people with bipolar spectrum disorder spend a considerably higher proportion of their time with depressive rather than manic symptoms. (12,13) This results in frequent confusion between depressive episodes that are part of a major depressive disorder and those that are part of the bipolar spectrum. (14) This confusion, in turn, leads people with bipolar spectrum disorders to often be incorrectly treated as if they have nonbipolar depression because they present with depressive symptoms. (15,16)
Exacerbating this problem is the fact that people with bipolar spectrum disorder often report considerably more distress associated with their depressive symptoms than with their hypomanic symptoms. (17) Incorrect treatment of bipolar depression with antidepressant medications can have dire consequences, including elevated risk of suicide, as well as increased healthcare costs. (18)
Because of these adverse consequences, it is important for behavioral health providers to screen for a history not only of bipolar disorders but also for a history of bipolar spectrum symptoms and family history of bipolarity at the onset of depression treatment. It would be prudent to avoid antidepressant monotherapy whenever there is any uncertainty regarding the existence of bipolarity. In addition, in light of their high prevalence, it eventually might be cost-effective to develop screening and outreach programs for people with bipolar spectrum disorders similar to the programs of this sort that exist for depression.
The major issues to consider in evaluating the cost-effectiveness of screening for bipolar spectrum disorders are the magnitude of the costs and the cost-effectiveness of currently available treatments in reducing these costs. The cost-effectiveness of treating bipolar I-II disorders is known to be quite high. (19,20) However, the cost-effectiveness of treating subsyndromal bipolar spectrum cases is largely unknown. Effectiveness trials are needed to provide an answer to this cost-effectiveness question. The focus of these trials, as of recent depression effectiveness trials, (21,22) might be on workplace costs of illness, given that so much of healthcare decision making is driven by institutional purchasers, although broader costs to patients, families, and society also need to be considered.
To decide whether to implement such effectiveness trials, some evidence is needed that bipolar spectrum disorders do, in fact, have substantial indirect costs over and above the already documented effects of depression. A number of recent cost-of-illness studies (23,25) and reviews (26,27) have focused on the costs of bipolar disorders. However, all of these studies confined their attention to bipolar I-II disorders. Furthermore, none of these studies presented data on the comparative effects of major depressive episodes associated either with major depressive disorder versus bipolar disorder or on the comparative effects of depressive and manic episodes associated with bipolar disorder. Nonetheless, other findings in the larger psychiatric epidemiologic literature raise the possibility that a more thorough investigation of the costs of bipolar spectrum disorders would find these conditions to be of sufficient importance to warrant the initiation of treatment effectiveness trials.
Perhaps the most important of these findings comes from long-term longitudinal data collected in the Collaborative Psychobiology of Depression study, the major source of prospective research information on the natural history of mood disorders in the general population. These data show clearly that the persistence and severity of major depressive episodes are greater among patients with bipolar depression than nonbipolar depression. (28) Workers with subsyndromal bipolar spectrum disorder have been found to have levels of role impairment intermediate between those of workers with bipolar I-II disorder and noncases. (29)
The most detailed published analysis of bipolar spectrum disorder prevalence was carried out by Judd and Akiskal, (11) who reanalyzed the more than 20,000 records in the Epidemiologic Catchment Area (ECA) Study database. They found, consistent with previous research, that roughly 1% of ECA respondents met criteria for bipolar I disorder and another 0.5% for bipolar II disorder. They then examined additional ECA respondents who they defined as subsyndromal bipolar cases if they had at least two lifetime manic or hypomanic symptoms below the threshold of at least one-week duration. An additional 5.1% of ECA respondents met these criteria. Importantly, these subsyndromal cases, like those in the National Comorbidity Survey Replication (NCS-R) database, exhibited impairments in functioning intermediate between those of bipolar I-II cases and of noncases in the general population.
Several depression cost-of-illness studies widely publicized over the past decade did not distinguish between depressive episodes that are part of a broad bipolar spectrum and those that are nonbipolar. (1,30,31) The most recent of these studies put the annual workplace costs of depression in the United States in the range of $30 to 50 billion. What proportion of these costs might be due to bipolar depression? Based on available evidence, it could be close to half. When these costs are combined with the as-yet undetermined costs of manic or hypomanic symptoms and episodes, the costs of bipolar spectrum disorders in terms of reduced productive functioning could well exceed those of nonbipolar depression.
A practical issue of considerable importance for treatment planning purposes is that the effects of bipolar disorder on loss of productive functioning are much more highly concentrated than those of nonbipolar depression: The costs of bipolar spectrum disorder are due to a smaller number of workers with a lifetime history of these disorders (5 to 8% of the population) than those with nonbipolar depression (12 to 15% of the population), each of whom has a more persistent and severe condition that leads to higher per-person role impairment than among people with a history of nonbipolar depression. This means that, all else equal, the cost-effectiveness of treating people with bipolar spectrum disorder is likely to be higher than that of treating people with non-bipolar depression. Innovations in secondary prevention based on the use of maintenance medications (32) and psychotherapies oriented toward relapse prevention (33) are of special relevance in this regard.
Based on these considerations, we believe that a program of epidemiologic and clinical research is called for that obtains accurate information on the prevalence of bipolar spectrum disorders, on the costs of bipolar spectrum disorders separately and in conjunction with the costs of nonbipolar depression, and on the cost-effectiveness of outreach and best-practice treatment of people with bipolar spectrum disorders.
Ronald C. Kessler, PhD, is a Professor of Health Care Policy at Harvard Medical School and a leading epidemiologist of psychiatric disorders.
Hagop S. Akiskal, MD, is a Professor of Psychiatry and the Director of the International Mood Center at the University of California, San Diego, and at the VA Psychiatry Service in San Diego. Dr. Akiskal also is the Editor of the Journal of Affective Disorders.
Minnie Ames, PhD, is an economist in the Department of Health Care Policy at Harvard Medical School.
Howard Birnbaum, PhD, and Paul E. Greenberg, MS, MA, are the Codirectors of the Health Economics Practice at Analysis Group, Inc., an economics research and consulting firm headquartered in Boston.
Robert M. Hirschfeld, MD, is the Chair of the Department of Psychiatry and Behavioral Sciences at the University of Texas Medical Branch in Galveston, Texas.
Philip S. Wang, MD, DrPH, is an Assistant Professor in the Department of Health Care Policy at Harvard Medical School and in the Division of Pharmacoepidemiology and Pharmacoeconomics at Brigham and Women's Hospital in Boston.
To send comments to the authors and editors, e-mail firstname.lastname@example.org.
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BY RONALD C. KESSLER, PHD; HAGOP S. AKISKAL, MD; MINNIE AMES, PHD; HOWARD BIRNBAUM, PHD; PAUL E. GREENBERG, MS, MA; ROBERT M. HIRSCHFELD, MD; AND PHILIP S. WANG, MD, DRPH
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|Title Annotation:||BIPOLAR DISORDER|
|Author:||Kessler, Ronald C.; Akiskal, Hagop S.; Ames, Minnie; Birnbaum, Howard; Greenberg, Paul E.; Hirschfel|
|Date:||Jan 1, 2007|
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