Abstract
Purpose::
Giant Cell Arteritis (GCA) has predilection for certain racial and northern geographic distributions. In the U.S. most patients share a northern European ancestry with a lower incidence in Hispanics and Asians. Alaska Natives share similar susceptibilities to genetically influenced diseases with their Pacific Rim neighbors. We surveyed the Alaska Native population for the incidence of this disease.
Methods::
All Alaska Natives are served exclusively by a network of affiliated Indian Health Service Hospitals, which has maintained a computerized diagnostic database for the last twenty years. A retrospective review of Medical Diagnoses codes for GCA, Temporal Artery Biopsy and AION was performed and evaluated for a biopsy proven diagnoses of Giant Cell Arteritis.
Results::
A total of 3 patients had positive biopsy results out of twenty biopsies that were performed on Alaska Natives in twenty years. All presented with new onset headache and other systemic complaints and had elevated westergrin sedimentation rates. There were 2 females and 1 male. The average presenting age was 71. Only one patient presented with visual symptoms and lost vision. Patients responded well to standard therapy and have all subsequently died from causes not related to GCA. These cases all came from coastal areas of Alaska where intermarriage with people of Russian and European ancestry was common. No cases where found from the more isolated central and northern population centers. The calculated incidence of GCA in the Alaska Native population is 1/100,000 in those over 50 years old. The percentage of positive biopsies (15%) in our survey is typical for other surveys done for this disease and represents a routine degree of clinical suspicion for the diagnosis.
Conclusions::
This is the first widespread, long-term study of a Native American population for the incidence of this disease. Our study suggests that GCA is essentially non-existent in a genetically isolated Alaska Native population. However, it does occur in the more racially diverse coastal regions where intermarriage is more common. The low incidence of GCA found in the Alaska Native population is similar to those rates reported for Japan and other pacific rim countries which share a common genetic heritage, but contrasts with high reported rates of European countries of equivalent northern latitudes. Our calculated incidence of 1/100,000 in those over 50 years old is similar to the incidence documented in Asian populations. Valuable population based studies in this geographically isolated population are made possible by a free and carefully monitored public health care system.
Keywords: genetics • clinical (human) or epidemiologic studies: prevalence/incidence • optic nerve