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Comorbidity and Diagnosing Depressive Disorders in Family Practice
We read with interest the article by Klinkman et al.1 In their cross-sectional–designed study, they compared the diagnoses of family physicians and DSM-III-R diagnoses based on the Structured Clinical Interview for DSM-III-R.
We support the attention for the false-positive misidentification of major depressive disorder (MDD) in primary care.2 The consequences of false-positive diagnosis of MDD might be unnecessary medical treatment, such as prescribing selective serotonin reuptake inhibitors. From a pharmacotherapeutic perspective, a precise diagnosis might be of less importance: most anxiety disorders are also treated with selective serotonin reuptake inhibitors.
In this respect, we are not informed by Klinkman et al1 whether other psychiatric disorders, such as anxiety disorders, were taken into account in the Structured Clinical Interview for DSM-III-R. The concurrence of mood disorders and anxiety disorders is high.2-3 Using the same data, Coyne et al4 found substantial psychiatric comorbidity in patients with MDD. Moreover, the number of false-positive diagnoses of MDD can be overestimated because of the Hawthorne effect.5
We performed a survey study on mental health problems in general practice in the area of Nijmegen, the Netherlands. We compared the diagnoses as registered by general practitioners (GPs) not involved in morbidity registration projects with DSM-IV diagnoses based on the Schedules for Clinical Assessment in Neuropsychiatry (SCAN).6 In this way, we studied everyday practice, overcame the Hawthorne effect, and took other mental disorders into account.
Of 21 patients with mood disorders (1 with bipolar disorder, 9 with depressive disorders, and 11 with other mood disorders, including dysthymia) diagnosed by the GP, 8 could be confirmed with the SCAN (6 cases of depressive disorder and 2 of dysthymia). In 5 patients, no DSM-IV diagnoses were made with the SCAN. The other DSM-IV diagnoses assigned by the SCAN were 4 anxiety disorders, 1 psychotic disorder, 1 somatoform disorder, and 2 sleeping disorders. In 3 cases, substance-related disorders were also diagnosed. Of the 21 patients with mood disorders diagnosed by the GP, 12 could theoretically be treated with selective serotonin reuptake inhibitors.
In line with Klinkman et al, we found a substantial number of false-positive GP diagnoses of mood disorders. Moreover, in nearly half of these patients, another serious mental disorder was found, and, in a few patients, no mental disorder could be established. We agree with the editorial by Block7 that GPs should not only make precise diagnoses of mood disorders but also should look to other significant mental disorders, especially when misidentification can have therapeutic implications.
Eric van Rijswijk, MD;
Eloy H. van de Lisdonk, MD, PhD;
Frans G. Zitman, MD, PhD
Nijmegen, the Netherlands
1. Klinkman MS, Coyne JC, Gallo S, Schwenk TL. False positives, false negatives, and the validity of the diagnosis of major depression in primary care. Arch Fam Med. 1998;7:451-461.
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2. Angst J. Depression and anxiety: a review of studies in the community and in primary health care. In: Sartorius N, Goldberg D, de Girolamo G, Costa e Silva JA, Lecrubier Y, Wittchen HU, eds. Psychological Disorders in General Medical Setting. Toronto, Ontario: Hans Huber Publishers; 1990:60-68.
3. Boulenger JP, Fournier M, Rosales D, Lavallee YJ. Mixed anxiety and depression: from theory to practice. J Clin Psychiatry. 1997;58(suppl 8):27-34.
4. Coyne JC, Fechner-Bates S, Schwenk TL. Prevalence, nature, and classification of depressive disorders in primary care. Gen Hosp Psychiatry. 1995;16:267-276.
5. Andersen B. Methodological Errors in Medical Research. Oxford, England: Blackwell Scientific Publications; 1990:92-93.
6. World Health Organization Joint Project on Diagnosis and Classification of Mental Disorders, Alcohol- and Drug-Related Problems. Schedules for Clinical Assessment in Neuropsychiatry. Version 2.1. Dutch version. Geneva, Switzerland: World Health Organization; 1996.
7. Block MR. Managing our depressed patients: gold standards vs higher standards. Arch Fam Med. 1998;7:462-464.
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In reply
We appreciate the interest in the clinical importance of accuracy of mood disorder classification shown by van Rijswijk and colleagues. They contend that the importance of DSM-IV–level precision in primary care diagnosis may be overstated, as several disorders may be treated with the same general approach, such as treating both major depressive disorder (MDD) and general anxiety disorder with selective serotonin reuptake inhibitors. They cite their own findings of Nijmegen general practitioner identification of mood disorders, which showed that a substantial proportion of patients with false-positive diagnoses of MDD had other serious mood disorders (eg, generalized anxiety disorder, dysthymia) that could be treated in the same way as MDD.
In our study, we were also able to establish the presence of other psychiatric disorders in our subjects, as all completed the Structured Clinical Interview for DSM-III-R at entry. Although substantial psychiatric comorbidity was present in subjects meeting the criteria for MDD (more than 48% had comorbid anxiety disorder, for example),1 the proportion of patients with false-positive diagnoses of MDD with threshold-level psychiatric comorbidity was much lower: only 8 (23%) of the 34 met the criteria for generalized anxiety disorder and 4 others met the criteria for any other diagnosis (including 1 case of dysthymia). This was not significantly higher than the proportion of true negatives meeting the criteria for generalized anxiety disorder (15%).
So, in contrast to the Nijmegen results, we did not discover a large reservoir of threshold-level mental health disorders in our patients with false-positive diagnoses—including anxiety disorders, which might respond to the same treatment approach as depression. As noted in our original article, most patients with false-positive diagnoses of MDD (74% [25/34]) did have a history of mental health treatment and were known to their physicians as patients with previous episodes of depression. Furthermore, many would have met the criteria for subthreshold depression or anxiety at entry into the study. These results, considered together and in light of the Nijmegen findings described above, underscore one of the main conclusions of our study: DSM-IV diagnostic categories assigned on the basis of a single interview result in an inaccurate portrayal of mood disorder "caseness"—particularly along the depression-anxiety spectrum. Patients may meet the criteria for generalized anxiety disorder at one interview, meet the criteria for minor depression at another interview, then meet the criteria for full MDD with limited-symptom panic or somatoform disorder at a third interview. Do they have 5 separate disorders, or do they have 1 disorder of varying intensity and manifestations?
The issue is not whether DSM-IV–level precision in primary care diagnosis may be overstated, but whether DSM-IV represents a valid framework for mental health problems in primary care. The absence of longitudinal data describing the natural history of mood symptoms in primary care patients cripples our efforts to answer this question or to create a new model that more accurately captures the ebb and flow of symptoms, impairment, and response to treatment. The results of these and other cross-sectional studies can only highlight the need to return to basics: longitudinal clinical epidemiologic studies in this area.
Michael S. Klinkman, MD, MS;
James C. Coyne, PhD;
Susan Gallo, PhD;
Thomas L. Schwenk, MD
Ann Arbor, Mich
1. Coyne JC, Fechner-Bates S, Schwenk TL. Prevalence, nature, and comorbidity of depressive disorders in primary care. Gen Hosp Psychiatry. 1995;16:267-276.
Arch Fam Med. 2000;9:123-124.
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