Epidemiology of sporadic inclusion body myositis and polymyositis in Olmsted County, Minnesota.
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.


CONCLUSIONS
The incidence and prevalence rates for sIBM are higher than previously reported.
Wilson
Floranne C
FC
Division of Rheumatology, Mayo Clinic, College of Medicine, Rochester, Minnesota 55905, USA. wilson.floranne@mayo.edu
Ytterberg
Steven R
SR
St Sauver
Jennifer L
JL
Reed
Ann M
AM
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004576:Electromyography; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D009132:Muscles / Q000473:pathology; D018979:Myositis, Inclusion Body / Q000453:epidemiology* / Q000473:pathology; D017285:Polymyositis / Q000453:epidemiology* / Q000473:pathology; D015995:Prevalence