Fatigue in primary care: prevalence, psychiatric comorbidity, illness behavior, and outcome

To identify the prevalence, psychiatric comorbidity, illness behavior, and outcome of patients with a presenting complaint of fatigue in a primary care setting.

686 patients attending two family medicine clinics on a self-initiated visit completed structured interviews for presenting complaints, self-report measures of symptoms and hypochondriasis, and the Diagnostic Interview Schedule (DIS). Fatigue was identified as a primary or secondary complaint from patient reports and questionnaires completed by physicians.

Of the 686 patients, 93 (13.6%) presented with a complaint of fatigue. Fatigue was the major reason for consultation of 46 patients (6.7%). Patients with fatigue were more likely to be working full or part time and to be French Canadian, but did not differ from the other clinic patients on any other sociodemographic characteristic or in health care utilization. Patients with fatigue received a lifetime diagnosis of depression or anxiety disorder more frequently than did other clinic patients (45.2% vs. 28.2%). Current psychiatric diagnoses, as indicted by the DIS, were limited to major depression, diagnosed for 16 (17.2%) fatigue patients. Patients with fatigue reported more medically unexplained physical symptoms, greater perceived stress, more pathologic symptom attributions, and greater worries about having emotional problems than did other patients. However, only those fatigue patients with coexisting depressive symptoms differed significantly from nonfatigue patients. Patients with fatigue lasting six months or longer compared with patients with more recent fatigue had lower family incomes and greater hypochondriacal worry. Duration of fatigue was not related to rate of current or lifetime psychiatric disorder. One half to two thirds of fatigue patients were still fatigued one year later.

In a primary care setting, only those fatigue patients who have coexisting psychological distress exhibit patterns of abnormal illness cognition and behavior. Regardless of the physical illnesses associated with fatigue, psychiatric disorders and somatic amplification may contribute to complaints of fatigue in less than 50% of cases presented to primary care.