Background: The prevalence of Parkinson disease (PD) varies by geographic location and ethnicity, but has never been studied among the Navajo.
Methods: Period prevalence was calculated using the number of people diagnosed with PD in the Shiprock Service Unit Indian Health Service database during 1995-1999, 2000-2004, and 2005-2009 as the numerator, and the number seen for any reason as the denominator. Age-standardized rates were calculated using the 2000 US population.
Results: During 2005-2009, 126 people were seen with PD (crude prevalence = 203.7/100,000 population). The age-adjusted rate was 335.9 (95% C. I. 277.8-394.0) overall, 438.5 (95% C.I. 336.5-540.5) in men and 259.7 (95% C.I. 192.8-326.7; p = 0.004) in women. The adjusted rate increased with age: 788.8 (95% C.I. 652.0-925.7) for age 40 and above to 1964.9 (95% C.I. 1613.7-2316.1) for age 60 and above. Adjusted rates were 246.6 (95% C.I. 187.2-306.0) in 1995-1999 and 284.7 (95% C.I. 227.0-342.4) in 2000-2004.
Conclusion: Parkinson disease appears common among the Navajo. Estimates increased with age and time, and were higher in men. In-person interviews are needed to confirm these estimates, and to determine incidence, quality of care, and risk factors for PD among the Navajo.