Fibromyalgia: prevalence, course, and co-morbidities in hospitalized patients in the United States, 1999-2007.

OBJECTIVES To evaluate hospitalisation data for patients with a primary or secondary fibromyalgia (FM) diagnosis. We estimated the number of men and women with an FM diagnostic code and compared them across a number of demographic and hospitalisation characteristics; examined age-specific, population-based FM hospitalisation rates; and determined the most common co-morbid diagnoses when FM was either the primary or secondary diagnostic code. METHODS Hospital discharge data from the Nationwide Inpatient Sample (NIS) were used. Records were evaluated between 1999 and 2007 that contained the International Classification of Diseases, 9th Revision, Clinical Modification FM diagnostic code (729.1, Myositis and Myalgia, unspecified), the FM criterion used in large-scale health services studies. RESULTS There were 1,727,765 discharges with a 729.1 diagnostic code (FM) during this nine-year span, 213,034 men (12.3%) and 1,513,995 women (87.6%). Discharges coded for FM increased steadily each year. The population-based rate of male FM discharges rose gradually across the lifespan; the rate for women rose sharply but then declined after age 64. Few differences between men and women across demographic and hospitalisation characteristics were evident. The most common co-morbidities with FM as the primary diagnosis were non-specific chest pain, mood disorders, and Spondylosis/intervertebral disc disorders/other back problems. Most common primary diagnoses, with FM as a secondary diagnosis, were essential hypertension, disorders of lipid metabolism, coronary atherosclerosis/other heart disease, and mental disorders. CONCLUSIONS A substantial number of U.S. residents with FM were hospitalised over the study period. Further analysis of hospitalisation data from patients with FM may provide guidance for both research and treatment, with the goal of improved care for FM patients.