INCIDENCE AND PREVALENCE OF HUNTINGTONS-DISEASE IN OLMSTED COUNTY, MINNESOTA (1950 THROUGH 1989)

Objective: To calculate average annual incidence rates for Huntington's disease (HD) from 1950 through 1989 and to estimate prevalence rates of the disease for January 1, 1960, and January 1, 1990. Design: Health care records from all sources, including hospitals, outpatient clinics, and long-term care institutions, are readily available for all inhabitants of Olmsted County, Minnesota. The diagnoses entered in these records have been coded and indexed. All health care records containing a diagnosis that might suggest HD were reviewed, and those patients for whom the symptoms of HD began between January 1, 1950, and December 31, 1989, were identified. We used specific criteria for diagnosing HD. Participants: Health care records were reviewed; residence in Olmsted County during the year of symptom onset was required. Main Outcome Measures: Average annual incidence rates and prevalence rates for January 1, 1960, and January 1, 1990. Results: Overall incidence rates were 0.4 (95% confidence interval I[I], 0.1 to 0.8) for women and 0.2 (95% CI, 0.04 to 0.6) for men per 100 000 person-years. Estimated prevalence rates for January 1, 1960, per 100 000 person-years were 6 (95% CI, 0.7 to 21.5) for women and 6.6 (95% CI, 0.8 to 23.8) for men. For January 1, 1990, the prevalence rates were 1.8 (95% CI, 0.04 to 10.2) for women and 2 (95% CI, 0.05 to 10.9) for men. Conclusions: Incidence and prevalence rates of HD in this community are similar to those reported in other communities. The small numbers of affected persons do not allow an estimate of variation over time.