Epidemiology of Sporadic Inclusion Body Myositis and Polymyositis in Olmsted County, Minnesota

FLORANNE C. WILSON, STEVEN R. YTTERBERG, JENNIFER L. St. SAUVER, and ANN M. REED

ABSTRACT.

Objective. To determine the incidence and prevalence of sporadic inclusion body myositis (sIBM) and polymyositis (PM) in a population-based study.

Methods. Charts of patients with myositis in Olmsted County, Minnesota, USA, from 1981 to 2000 were reviewed.

Results. For sIBM, the age- and sex-adjusted incidence rates per 100,000 were 0.79 (95% confidence interval = 0.24–1.35), and for PM, 0.41 (95% CI 0.08–0.73). The age- and sex-adjusted prevalence rates per 100,000 were 7.06 (95% CI 0.87–13.24) for sIBM and 3.45 (95% CI 0.00–7.35) for PM.

Conclusion. The incidence and prevalence rates for sIBM are higher than previously reported. (First Release Jan 15 2008; J Rheumatol 2008;35:445-7)

Key Indexing Terms:

INCLUSION BODY MYOSITIS
POLYMYOSITIS
INCIDENCE
PREVALENCE

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From the Divisions of Rheumatology, Pediatric Rheumatology, and Health Sciences Research, Mayo Clinic, College of Medicine, Rochester, Minnesota, USA.

F.C. Wilson, MD, Clinical Fellow; S.R. Ytterberg, MD, Associate Professor of Medicine, Division of Rheumatology; J.L. St. Sauver, PhD, MPH, Assistant Professor, Division of Health Sciences Research; A.M. Reed, MD, Professor of Medicine and Pediatrics, Divisions of Pediatrics and Rheumatology, Mayo Clinic College of Medicine.

Address reprint requests to Dr. F. Wilson, Division of Rheumatology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905. E-mail: wilson.floranne@mayo.edu

Accepted for publication October 15, 2007.

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