The Incidence of Fibromyalgia and Its Associated Comorbidities: A Population-Based Retrospective Cohort Study Based on International Classification of Diseases, 9th Revision Codes.
Weir, Peter T. MD *; Harlan, Gregory A. MD, MPH +; Nkoy, Flo L. MD, MS, MPH +; Jones, Spencer S. BS *; Hegmann, Kurt T. MD, MPH ++; Gren, Lisa H. MSPH *; Lyon, Joseph L. MD, MPH *
JCR: Journal of Clinical Rheumatology.
12(3):124-128, June 2006.
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Background: The epidemiology of fibromyalgia is poorly defined. The incidence of fibromyalgia has not been determined using a large population base. Previous studies based on prevalence data demonstrated that females are 7 times more likely to have fibromyalgia than males and that the peak age for females is during the childbearing years.
Objective: We have calculated the incidence rate of fibromyalgia in a large, stable population and determined the strength of association between fibromyalgia and 7 comorbid conditions.
Methods: We conducted a retrospective cohort study of a large, stable health insurance claims database (62,000 nationwide enrollees per year). Claims from 1997 to 2002 were examined using the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes to identify fibromyalgia cases (ICD code 729.1) and 7 predetermined comorbid conditions.
Results: A total of 2595 incident cases of fibromyalgia were identified between 1997 and 2002. Age-adjusted incidence rates were 6.88 cases per 1000 person-years for males and 11.28 cases per 1000 person-years for females. Females were 1.64 times (95% confidence interval = 1.59-1.69) more likely than males to have fibromyalgia. Patients with fibromyalgia were 2.14 to 7.05 times more likely to have one or more of the following comorbid conditions: depression, anxiety, headache, irritable bowel syndrome, chronic fatigue syndrome, systemic lupus erythematosus, and rheumatoid arthritis.
Conclusion: Females are more likely to be diagnosed with fibromyalgia than males, although to a substantially smaller degree than previously reported, and there are strong associations for comorbid conditions that are commonly thought to be associated with fibromyalgia.
(C) 2006 Lippincott Williams & Wilkins, Inc.