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The Epidemiology and Recognition of Pain and Physical Symptoms in Depression

Rakesh Jain, MD, MPH

Psychiatric Drug Research, R/D Clinical Research, Inc, Lake Jackson, Tex

Epidemiology of Pain and Physical Symptoms in Patients With Depression

Individuals with major depressive disorder (MDD) often present with a variety of somatic symptoms in addition to the common emotional symptoms.1 Somatic symptoms include not only fatigue and insomnia1 but also physical pain,2 such as headaches, neck pain, chest pain, abdominal pain, limb pain, joint disease, backaches, and gastrointestinal disease. These chronic, painful physical symptoms are common in the community, but more so in individuals with MDD, as well as in women, and these conditions worsen with age. A community survey2 of 18,980 Europeans found that, of the 4% of respondents with MDD, 43% reported having at least 1 chronic painful physical condition (AV 1AV 1), whereas only 16% of those without MDD had a chronic painful physical condition.

In an international study of depression and somatic symptoms (N = 5447), Simon et al.3 reported that the somatization of depression, as defined by somatosensory amplification (having MDD but reporting multiple unexplained physical symptoms), occurred in 50% of patients at primary care centers. Although the prevalence of MDD varied from 1.5% to 27.3% across the 15 study centers, an almost 1:1 relationship was found between patients’ reported psychological symptoms of depression and the number of reported physical symptoms. These results suggest that, internationally, major depression is a disorder comprised fairly equally of both emotional and physical symptoms.

A meta-analysis of 14 studies in a variety of research and real-world settings by Bair et al.4 found that, overall, 65% of patients with MDD reported painful physical symptoms. Often, clinicians in psychiatry tend to believe that patients do not have that many painful physical symptoms, which may bias the questions asked and the responses given. The researchers clarified that this prevalence was not influenced by psychiatric versus primary care settings.

The diffuse nature of physical symptoms is the hallmark of major depression, which, in addition to the aforementioned painful symptoms, can also include symptoms such as weakness, muscle soreness, chilly hands and feet, dizziness, numbness, trouble with vision or hearing, and a lump-in-throat feeling.5 The most commonly reported symptom according to a recent study (N = 2191) by Vaccarino et al.5 was “feeling fatigued, weak, or tired all over.” This symptom had a high correlation (r = 0.50) with patients’ overall scores on the Hamilton Rating Scale for Depression (HAM-D). Further, the rates of symptom intensity (according to the Somatic Symptoms Inventory) tended to increase depending on the severity of the depression as measured by the HAM-D. Therefore, not only should clinicians screen for painful physical symptoms in patients with MDD, but they should also be aware that the severity of depression may impact the level of impairment caused by physical symptoms.

Data from the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study,6 which included both primary care and psychiatric outpatients with nonpsychotic MDD, showed that almost 80% of patients complained about physical pain (AV 2AV 2). Further, patients who complained of pain were more likely to also report a poorer quality of life than those who did not have pain complaints.

The important message about the co-occurrence of physical symptoms in patients with depression is that painful physical conditions and other somatic symptoms are highly prevalent in all patients with MDD. Pain is not only common, but also can be severe and impairing.

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Recognizing Depression in Patients With Pain and Physical Symptoms

Because depression and pain often co-occur, clinicians must be aware of the nature of each condition and be able to recognize this comorbidity. Yet, when patients report physical symptoms, especially pain, and do not report anhedonia or dysphoria, physicians’ ability to accurately diagnose MDD can be impaired.

For example, in the meta-analysis by Bair et al.,4 at least half of the patients with major depression in primary care were initially misdiagnosed and received no treatment for depression. A majority of patients with MDD presented with only somatic symptoms.

The more physical symptoms the patient reports, the greater the likelihood that the patient has a mood or anxiety disorder (AV 3AV 3).7 However, primary care patients seldom attribute their pain symptoms to depression or other psychiatric illness and, when questioned, may even deny or dismiss having a depressed mood.3,7,8 Thus, the clinician must consider MDD in the differential diagnosis despite patients with multiple physical symptoms not reporting depressed mood.

Conclusion

Chronic pain and physical symptoms are common in patients with mood symptoms, and the presence of painful physical symptoms makes the recognition of mood symptoms more difficult (AV 4AV 4). Clinicians in both psychiatric and primary care settings should remember that depression is a disorder of both psychological and somatic symptoms, which can include pain. Being aware of this common co-occurrence can increase the rate of accurate detection of MDD in patients presenting with somatic symptoms.

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References

  1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision. Washington, DC: American Psychiatric Association; 2000
  2. Ohayon MM. Specific characteristics of the pain/depression association in the general population. J Clin Psychiatry 2004;65(suppl 12):5–9
  3. Simon GE, VonKorff M, Piccinelli M, et al. An international study of the relation between somatic symptoms and depression. N Engl J Med 1999;341:1329–1335
  4. Bair MJ, Robinson RL, Katon W, et al. Depression and pain comorbidity: a literature review. Arch Intern Med 2003;163:2433–2445
  5. Vaccarino AL, Sills TL, Evans KR, et al. Prevalence and association of somatic symptoms in patients with major depressive disorder. J Affect Disord 2008;110:270–276
  6. Husain MM, Rush AJ, Trivedi MH, et al. Pain in depression: STAR*D study findings. J Psychosom Res 2007;63:113–122
  7. Kroenke K, Jackson JL, Chamberlin J. Depressive and anxiety disorders in patients presenting with physical complaints: clinical predictors and outcomes. Am J Med 1997;103:339–347
  8. Katon W. Depression: a relationship to somatization and chronic mental illness. J Clin Psychiatry 1984;45(3, pt 2):4–12