Incidence and prevalence of Parkinson's disease among Navajo people living in the Navajo nation

AbstractParkinson's disease (PD) is largely unstudied among American Indians. Unique populations might harbor clues to elusive causes. We describe the incidence and prevalence of PD among Navajo people residing in the Navajo Nation, home to the largest American Indian tribe in the United States. We analyzed 2001‐2011 inpatient and outpatient visit data for Navajo people obtained from the Indian Health Service, which provides health care to American Indian people living on the Navajo Reservation. Cases were defined by at least two inpatient or outpatient visits with the diagnosis of PD. Crude and age‐adjusted incidence and prevalence rates were calculated overall as well as by age, sex, region of residence, and time period. Five hundred twenty‐four Navajo people with median age‐at‐onset of 74.0 years were diagnosed with PD during the study period, yielding an average annual crude incidence rate of 22.5/100,000. Age‐specific incidence was 232.0 for patients 65 years of age or older and 302.0 for 80 years of age or older. Age‐adjusted incidence was 35.9 overall (238.1 for ≥65 years), was higher in men than in women (47.5 vs. 27.7; P < 0.001), varied by region (P = 0.03), and was similar between time periods (2002‐2004 vs. 2009‐2011). The age‐adjusted point prevalence rate was 261.0. The rate of PD among Navajo People appears to be as high as or higher than rates reported in many other populations. Rates increased to the highest age group, consistent with population‐based studies. Further investigation is warranted to examine risk factors for PD in this remote population. © 2015 International Parkinson and Movement Disorder Society