Prevalence of rheumatoid arthritis in circumpolar native populations.

OBJECTIVE: To compare the prevalence of rheumatoid arthritis (RA) in related, but geographically separate, indigenous circumpolar populations. METHODS: Cases were identified by community survey in Russia and by examination of cases located through arthritis registries, a computerized patient information database, and query of local health care providers in Alaska. All possible cases were verified by examination and application of the American College of Rheumatology 1987 criteria. RESULTS: The prevalence rates of RA (age standardized to US population of 1980) varied from 0.62% in the Alaskan Yupik to 1.78% in the Alaskan Inupiat. The Russian Chukchi rate was 0.73% and that of the Siberian Eskimo was 1.42%. CONCLUSION: The Alaskan Yupik Eskimo and Chukchi natives had prevalence rates of RA within the usual range of North American Caucasian groups, in contrast to the Russian Siberian Eskimo and the Alaskan Inupiat Eskimo of the Barrow region, whose high rates approached those of unrelated North American native groups living in very different environments. The Alaskan Inupiat rate was significantly higher than that of the Alaskan Yupik (OR = 2.51, 95% CI 1.25-5.07; p = 0.013), but statistical inferences are limited in the Russian study populations by the small case numbers. The high prevalence rates probably have a genetic basis, although an environmental influence cannot be excluded.

Spondylarthropathic diseases in indigenous circumpolar populations of Russia and Alaska.

AIMS: To compare the nature and frequency of spondylarthropathy in geographically separated but genetically related populations with a high prevalence of HLA-B27. METHODS: Using a common questionnaire and disease criteria, cases were ascertained through cross-sectional community surveys in Russia and by examination and study of possible cases identified through rheumatic disease registries and the Native Health Service's computerized patient care data system in Alaska. RESULTS: Similar overall prevalences of spondyloarthropathy (2.0-3.4%) and a similar spectrum of disease were found, including reactive arthritis, ankylosing spondylitis and undifferentiated spondylarthropathy. Psoriatic arthritis was very rare. CONCLUSION: No predisposition to one particular form of spondyloarthropathy was observed; genetic and microbial settings for a spectrum of disease were present. Among adults positive for the presence of HLA-B27 the prevalence of all types of spondylarthropathies was estimated to be 4.5%, all populations combined, and the prevalence of AS was estimated to be 1.6%.

Spondyloarthropathies in circumpolar populations: II. Characterization of the populations.

For epidemiologic studies of spondyloarthropathy in circumpolar peoples of Chukotka, Russia and Alaska, we gathered demographic, physical and laboratory data to provide a background for evaluating and comparing factors that may influence susceptibility and clinical expression of disease. The study groups included the Chukchi and Siberian Eskimo of Russia and the Inupiat and Yupik Eskimo of Alaska. The 4 groups were remarkably similar in population structure, educational attainment, mean hemoglobin concentrations and frequency of the Class I histocompatibility antigen HLAB27. The Alaskan and Chukotkan groups were similar in mean height, but the Alaskans had higher body weights and significantly greater body mass indexes, probably a reflection of a shift away from traditional lifestyle and diet. Differences in the frequencies of ABO and MN blood group antigens were also apparent, with higher frequencies of blood group M in the Alaskan populations, particularly the Inupiat.

Spondyloarthropathies in circumpolar populations: I. Design and methods of United States and Russian studies.

Parallel epidemiologic studies of spondyloarthropathy in aboriginal circumpolar populations were carried out by U.S. and Russian investigators. These complementary studies used the same data collection instrument and disease criteria to facilitate comparisons. During three expeditions to Siberia, Russian investigators collected cross-sectional data from four settlements of Eskimos and Chukchi Indians on the Chukotka peninsula for a study of disease prevalence. U.S. researchers collected cross-sectional data from Eskimos in four Alaskan regions for studies of prevalence and longitudinal data for studies of clinical manifestations, natural history, disease impact, and health care utilization. The aims of these studies were to describe the spectrum of spondyloarthropathy in these populations, and to lay the groundwork for investigations of the role of specific genetic and environmental factors in the pathogenesis and expression of disease. These studies were carried out with a minimum disruption to the native people.

HLA class II and HLA-B27 oligotyping in two Siberian native population groups.

It was the purpose of this study to better define the frequency of HLA-B27 subtypes and HLA class II alleles among indigenous populations from the eastern tip of the Chukotka Peninsula of Siberia, Russia, which have higher frequencies of HLA-B27 (40%) and spondyloarthropathies (2%) than Caucasian populations and test the hypothesis that these populations are more closely related to Orientals. Siberian Eskimos and Chukchi residing in four coastal villages on the Chukotka Peninsula inhabited by Siberian Eskimos and Chukchi people were examined using oligotyping of the polymerase-chain reaction-amplified second and third exons of the HLA-B27 gene. HLA-class II alleles (DRB1, DQA1 and DQB1) were similarly determined. Of 88 HLA-B27 positive individuals from these villages, all had HLA-B*2705, including the four patients with Reiter's syndrome and the five ankylosing spondylitis, except one Eskimo control who had HLA-B*2702. None had HLA-B*2704, a frequent subtype in Orientals. HLA-class II typing in 70 Siberian Eskimos and 71 Siberian coastal Chukchi revealed HLA-DRB1*0401, DRB1*0802, *0901 and *1402 to account for nearly all the DRB1 alleles found in this population, similar to what has been described in Eskimos in Alaska, but different from Chinese or native Americans in the U.S. The overwhelming majority of the individuals examined had HLA-DQB1*0301, similar to what has been observed in Native Americans. The Siberian Eskimos differed from the coastal Chukchi only in the occurrence of HLA-DRB1*0701, DQA1*0201, DQB1*0201 alleles, which occurred only in the former group. These data suggest that the Chukotka population is genetically more closely related to Caucasians and native Americans and less to other Oriental populations.

"Cross-sectional" study of low back pain among workers at an industrial enterprise in Russia.

STUDY DESIGN: A representative sample of 18- to 65-year-old workers from a machine-building factory was studied using a standardized questionnaire. OBJECTIVES: To study the prevalence of low back pain syndrome among workers at an industrial enterprise and to estimate the association between low back pain syndrome and certain factors. METHODS: This was a cross-sectional study of 800 workers (400 men and 400 women), who were invited to participate in the study. Seven-hundred-and-one (87.6%) persons took part in the study--339 (84.7%) men and 362 (90.5%) women. RESULTS: The life-time prevalence of low back pain complaints was 48.2%. The prevalence during the last year was 31.5%, and point prevalence was 11.5%. The number of patients with low back pain complaints increased with age. The duration of a low back pain episode was less than 2 weeks in 88.2% of the patients, and more than 12 weeks in only in 1.8% of the patients. Analysis of some social, individual, and professional factors revealed associations between low back pain and low level of education, marital status, absence of sports activity, intensity of smoking, and frequent lifting and bending during the work day. CONCLUSION: Our study revealed a high prevalence of low back pain among workers at an industrial enterprise. This low back pain was primarily of an acute nature.

HLA-B27 subtypes among the Chukotka Native groups.

The purpose of this study was to assess the relative frequency of the known HLA-B27 subtypes in HLA-B27 positive Chukotka natives, which have higher frequencies of HLA-B27 (to 40%) and spondyloarthropathies (to 2%) than the Russian Caucasian population. Using oligotyping of the polymerase-chain reaction amplified second and third exons of the HLA-B27 gene in 86 DNA samples from HLA-B27 positive individuals were successfully typed. All had HLA-B*2705, including 4 patients with Reiter's syndrome and 5 with ankylosing spondyloarthritis, except one Eskimo who had HLA-B*2702. None had HLA-B*2704, a frequent subtype in Orientals. With respect to HLA-B27 subtypes the indigenous populations from the eastern part of the Chukotka Peninsula are genetically more closely related to Caucasians than to Orientalis.

Prevalence of spondyloarthropathies and HLA-B27 in the native population of Chukotka, Russia.

OBJECTIVE: We sought to determine the prevalence and nature of spondyloarthropathies (SPA) and the prevalence of HLA-B27 in the native selected circumpolar population of Chukotka, Russia. METHODS: We conducted a cross sectional study that included medical examinations and interviews of 355 of 498 (71.3%) native residents of 2 Eastern Chukotka settlements, Enmelen and Nunligran. RESULTS: Among them were 268 Chukchas, 7 Eskimos, and 80 subjects of mixed race. There were 9 subjects (2.5%) with SPA, 3 of 7 Chukchas had ankylosing spondylitis (AS) (1.1%), 2 reactive arthritis (ReA), 2 with undifferentiated SPA. Among the mixed race persons one Chukcha-Eskimo had AS, one Eskimo-Russian had psoriatic arthritis (PsA). We found a high percentage of HLA-B27 antigen in the population, 34% in Chukcha natives and 25% in mixed race. CONCLUSION: Our data complement other studies of circumpolar populations and reinforce the reported high prevalences of SPA and HLA-B27 among those populations.

Spondyloarthropathies in circumpolar populations of Chukotka (Eskimos and Chukchi): epidemiology and clinical characteristics.

OBJECTIVE: We sought to determine the prevalence of HLA-B27 and the prevalence and nature of spondyloarthropathies in the native residents of Eastern Chukotka, Siberia, Russia. METHODS: We conducted a cross sectional study with medical examination and interview of 464 of 640 (72.5%) native residents of 2 Eastern Chukotka settlements, Sireniki and Novo-Chaplino. RESULTS: Among them were 212 Eskimos, 98 Chukchi and 154 subjects of mixed race. There were 2 subjects (0.4%) with ankylosing spondylitis, 2 with Reiter's syndrome, 2 with undifferentiated spondyloarthropathy and 1 with late onset pauciarticular juvenile arthritis consistent with spondyloarthropathy. Four of the subjects were Eskimos, 2 were of mixed race, and 1 was Chukchi. We found a high percentage of HLA-B27 antigen in the population, 32% in the native population overall, and 40% among the Eskimos. CONCLUSION: Our data complement other studies of circumpolar populations and reinforce the reported high prevalence of spondyloarthropathy and HLA-B27 among those people.