longitudinal study – Page 6 – American ME and CFS Society

Abstract:

OBJECTIVES: To investigate the point prevalence of the chronic fatigue syndrome and unexplained debilitating chronic fatigue in a community-based sample of persons and to describe demographic, clinical, and psychosocial differences among those with the chronic fatigue syndrome, those with chronic fatigue, and healthy controls.

DESIGN: Prospective cohort study.

SETTING: A health maintenance organization in Seattle, Washington.

PARTICIPANTS: A random sample of 4000 members of the health maintenance organization was surveyed by mail for the presence of chronic fatigue.

MEASUREMENTS: Persons with chronic fatigue were evaluated using a questionnaire that requested information about medical history and fatigue and related symptoms; validated measures of functional status and psychological distress; a physical examination; and standardized blood tests. A structured psychiatric interview was done in persons who appeared to meet the original Centers for Disease Control and Prevention (CDC) criteria for the chronic fatigue syndrome. Participants completed self-report measures at 12 and 24 months. Those with chronic fatigue were reevaluated in person 1 year after study enrollment.

RESULTS: 3066 (77%) of the 4000 members surveyed responded. Chronic fatigue was reported by 590 persons (19%). Of these, 388 (66%) had a medical or psychiatric condition that could account for the fatigue. Of the 74 persons (37%) with chronic fatigue who were enrolled in the study, only 3 met the CDC criteria for the chronic fatigue syndrome. The remaining 71 persons were designated as having chronic fatigue alone. Seventy-four healthy, age- and sex-matched controls who were drawn from the same sample but who denied having chronic fatigue were also studied. Demographic characteristics were similar in persons with the chronic fatigue syndrome, persons with chronic fatigue alone, and controls. Those with the chronic fatigue syndrome or chronic fatigue alone had more frequent cervical and axillary adenopathy, poorer functional status, and greater psychological distress than controls. Women and minorities were not overrepresented among cases with chronic fatigue.

CONCLUSIONS: Using different assumptions about the likelihood that persons who did not participate in the study had the chronic fatigue syndrome, the estimated crude point prevalence of the syndrome in this community ranged from 75 to 267 cases per 100,000 persons. The point prevalence of chronic fatigue alone was strikingly higher; it ranged from 1775 to 6321 cases per 100,000 persons.

Source: Buchwald D, Umali P, Umali J, Kith P, Pearlman T, Komaroff AL. Chronic fatigue and the chronic fatigue syndrome: prevalence in a Pacific Northwest health care system. Ann Intern Med. 1995 Jul 15;123(2):81-8. http://www.ncbi.nlm.nih.gov/pubmed/7778839

Abstract:

OBJECTIVE: To examine the predictors of long term outcome for patients with the chronic fatigue syndrome.

DESIGN: Cohort study.

SUBJECTS: 139 subjects previously enrolled in two treatment trials; 103 (74%) were reassessed a mean of 3.2 years after start of the trials.

SETTING: University hospital referral centre.

MAIN OUTCOME MEASURES: Age at onset, duration of illness, psychological and immunological status at initial assessment. Ongoing symptom severity, levels of disability, and immunological function at follow up.

RESULTS: 65 subjects had improved but only six reported no current symptoms. An alternative medical diagnosis had been made in two and psychiatric illness diagnosed in 20. The assignment of a primary psychiatric diagnosis at follow up and the strength of the belief that a physical disease process explained all symptoms at entry to the trials both predicted poor outcome. Age at onset of illness, duration of illness, neuroticism, premorbid psychiatric diagnoses, and cell mediated immune function did not predict outcome.

CONCLUSION: Though most patients with the chronic fatigue syndrome improve, a substantial proportion remain functionally impaired. Psychological factors such as illness attitudes and coping style seem more important predictors of long term outcome than immunological or demographic variables.

Comment in:

Chronic fatigue syndrome. Distinguish between syndromes… [BMJ. 1994]

Chronic fatigue syndrome. Immunological findings vary between populations. [BMJ. 1994]

Chronic fatigue syndrome. Role of psychological factors overemphasised. [BMJ. 1994]

Source: Wilson A, Hickie I, Lloyd A, Hadzi-Pavlovic D, Boughton C, Dwyer J, Wakefield D. Longitudinal study of outcome of chronic fatigue syndrome. BMJ. 1994 Mar 19;308(6931):756-9. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2539669/

You can read the full article here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2539669/pdf/bmj00432-0032.pdf