Rheumatoid arthritis in the Pima Indians: the intersection of epidemiologic, demographic, and genealogic data

Characterization of indigenous community engagement in arthritis studies conducted in Canada, United States of America, Australia and New Zealand

BACKGROUND

Research adhering to community engagement processes leads to improved outcomes. The level of Indigenous communities' engagement in rheumatology research is unknown.

OBJECTIVE

To characterize the frequency and level of community engagement reporting in arthritis studies conducted in Australia (AUS), Canada (CAN), New Zealand (NZ) and the United States of America (USA).

METHODS

Studies identified through systematic reviews on topics of arthritis epidemiology, disease phenotypes and outcomes, health service utilization and mortality in Indigenous populations of AUS, CAN, NZ and USA, were evaluated for their descriptions of community engagement. The level of community engagement during inception, data collection and results interpretation/dissemination stages of research was evaluated using a custom-made instrument, which ranked studies along the community engagement spectrum (i.e. inform-consult-involve-collaborate-empower). Meaningful community engagement was defined as involving, collaborating or empowering communities. Descriptive analyses for community engagement were performed and secondary non-parametric inferential analyses were conducted to evaluate the possible associations between year of publication, origin of the research idea, publication type and region of study; and meaningful community engagement.

RESULTS

Only 34% (n = 69) of the 205 studies identified reported community engagement at ≥ 1 stage of research. Nearly all studies that engaged communities (99% (n = 68)) did so during data collection, while only 10% (n = 7) did so at the inception of research and 16% (n = 11) described community engagement at the results' interpretation/dissemination stage. Most studies provided community engagement descriptions that were assessed to be at the lower end of the spectrum. At the inception of research stage, 3 studies reported consulting communities, while 42 studies reported community consultation at data collection stage and 4 studies reported informing or consulting communities at the interpretation/dissemination of results stage. Only 4 studies described meaningful community engagement through all stages of the research. Inferential statistics identified that studies with research ideas that originated from the Indigenous communities involved were significantly more associated with achieving meaningful community engagement.

CONCLUSIONS

The reporting of Indigenous community engagement in published arthritis studies is limited in frequency and is most frequently described at the lower end of the community engagement spectrum. Processes that support meaningful community engagement are to be promoted.

Systematic review of rheumatic disease phenotypes and outcomes in the Indigenous populations of Canada, the USA, Australia and New Zealand

We performed a systematic review designed to characterize clinical phenotypes and outcomes in Indigenous populations with rheumatic disease to enhance the understanding of how rheumatic disease presents in Indigenous populations and allow for better projection of the healthcare needs of the communities affected. A systematic search was performed in medical (Medline, EMBASE, CINAHL), Indigenous and conference abstract databases (to June 2015). Search terms for Indigenous populations were combined with terms for inflammatory arthritis conditions, connective tissue disorders, crystal arthritis and osteoarthritis. Studies were included if they reported on disease features, disease activity measures, or patient-reported outcomes in Canadian, American, Australian or New Zealand Indigenous populations. Data were extracted in duplicate, and a narrative summary was prepared. A total of 5269 titles and abstracts were reviewed, of which 504 underwent full-text review and 85 met inclusion criteria. Nearly all the studies described outcomes in the North American populations (n = 77), with only four studies from Australia and four studies from New Zealand. The majority of studies were in rheumatoid arthritis (n = 31) and systemic lupus erythematosus (n = 19). Indigenous patients with rheumatoid arthritis had higher disease activity and reported more significant impact on patient-reported outcomes and quality of life than non-Indigenous patients. Spondyloarthropathy features were described in North American populations, with most patients having advanced manifestations. In systemic lupus erythematosus, nephritis was more frequent in Indigenous populations. Gout and osteoarthritis were more severe in New Zealand Maori populations. The existing literature supports differences in disease phenotype and severity in Indigenous populations of Canada, America, Australia and New Zealand. We encourage investigators in this area of research to undertake contemporary studies that disentangle differences between phenotype and severity that are biologic in etiology or merely reflecting differences in access to care and that provide a longitudinal assessment of outcomes in more diverse populations.

Systemic sclerosis in Canada's North American Native population: assessment of clinical and serological manifestations

OBJECTIVE

Certain North American Native (NAN) populations are known to have higher rates of systemic sclerosis (SSc) compared to non-NAN; however, little is known of the specific disease characteristics in this population in Canada. This study compares the clinical and serological manifestations of SSc in NAN and white patients.

METHODS

This cross-sectional, multicenter study included subjects enrolled in the Canadian Scleroderma Research Group registry between September 2004 and June 2012. Subjects were evaluated with complete medical histories, physical examinations, and self-questionnaires. Ethnicity was defined by self-report. Disease characteristics were compared between NAN and white patients and multivariate analyses were performed to determine the independent association between ethnicity and various clinical manifestations.

RESULTS

Of 1278 patients, 1038 (81%) were white, 71 (6%) were NAN, and 169 (13%) were classified as non-white/non-NAN. There were important differences between NAN and white subjects with SSc. In multivariate analysis adjusting for socioeconomic differences and smoking status, NAN ethnicity was an independent risk factor for the severity of Raynaud phenomenon and more gastrointestinal symptoms, and was associated with a nonsignificant increase in the presence of digital ulcers.

CONCLUSION

NAN patients with SSc have a distinct clinical phenotype. Our study provides a strong rationale to pursue further research into genetic and environmental determinants of SSc.

Familial clustering of the serum cytokine profile in the relatives of rheumatoid arthritis patients

OBJECTIVE

Rheumatoid arthritis (RA) is prevalent in North American Native populations, with a high frequency of multicase families and seropositivity in first-degree relatives. This study was undertaken to determine whether the serum cytokine profile of first-degree relatives of North American Native patients with RA differed from that of individuals with no family history of autoimmunity and whether there was an association with RA autoantibodies.

METHODS

North American Native patients with RA (n = 105), their first-degree relatives (n = 273), healthy North American Native controls (n = 200), and Caucasian controls (n = 150) were studied. Serum levels of 42 cytokines were tested using a multiplex laser bead assay. Rheumatoid factor (RF), anti-cyclic citrullinated peptide 2 (anti-CCP-2), monocyte chemotactic protein 1 (MCP-l), and high-sensitivity C-reactive protein (hsCRP) were tested by enzyme-linked immunosorbent assay, and HLA-DRB1 alleles by specific primers. Discriminant analysis and logistic regression classified individuals based on their cytokine profile.

RESULTS

The prevalence of RF (cutoff level predetermined to include 5% of Caucasian controls) and anti-CCP (cutoff level of ≥40 units) was, respectively, 88% and 81% in the RA patients, 34% and 9% in first-degree relatives, and 9% and 4% in North American Native controls; the prevalence of anti-CCP was 0% in Caucasian controls. Levels of most cytokines were highest in RA patients; 17 of 40 cytokines (43%) were significantly higher in first-degree relatives than in controls, including multiple proinflammatory cytokines. Discriminant analysis showed a notable distinction between the groups, with 85% classification accuracy. First-degree relatives had markedly higher MCP-1 and hsCRP levels than North American Native controls, but there was no consistent association with RA autoantibodies.

CONCLUSION

Our findings indicate that levels of multiple cytokines and hsCRP are higher in first-degree relatives of North American Native patients with RA compared to individuals from a nonautoimmune background. These data suggest that elevated baseline cytokine levels may be part of the risk profile for developing RA.

Rheumatoid arthritis in a north american native population: longitudinal followup and comparison with a white population

OBJECTIVE

To describe differences in phenotype and outcomes in North American Native (NAN) patients with rheumatoid arthritis (RA) followed prospectively and compared to white patients with RA.

METHODS

Patients from a single academic center were followed over 20 years using a custom database. Data included diagnoses, year of disease onset, ethnicity, modified Health Assessment Questionnaire (mHAQ) score, patient and physician global scores, tender and swollen joint counts, treatment, serology, and erythrocyte sedimentation rate (ESR). Records of all white (n = 1315) and NAN (n = 481) patients with RA were abstracted. Cumulative treatment data and clinical measures were compared.

RESULTS

Disease duration was longer in white patients compared to NAN patients (16 +/- 11 vs 14 +/- 10 years, respectively; p = 0.03). Onset age was 34 years for NAN patients and 43 years for white patients (p < 0.001). NAN patients were more frequently positive for rheumatoid factor (89% vs 74%; p < 0.001) and antinuclear antibody (57% vs 21%; p < 0.001). Although mean tender joint counts and swollen joint counts were similar, NAN patients had higher Lansbury scores (weighted joint count; 66.5 vs 49.7; p < 0.001), mHAQ scores (1.1 vs 0.9; p = 0.001), and ESR (31 vs 25 mm/h; p < 0.012). NAN patients had more frequent knee (53% vs 34%; p < 0.001) and elbow (62% vs 48%; p = 0.007) involvement. Compared to white patients, NAN patients took a higher lifetime number of disease-modifying antirheumatic drugs (3.2 +/- 1.9 vs 2.2 +/- 1.7; p < 0.001), had more combination therapy (38% vs 29%; p = 0.002), and had more frequent prednisone use (55% vs 39%; p < 0.001).

CONCLUSION

Compared to white patients, NAN patients with RA develop disease earlier, are more frequently seropositive, have greater large joint involvement, and greater disease burden, although treatment is more aggressive. These differences are present early and persist throughout the disease course.

Immunogenetic Risks of Anti-Cyclical Citrullinated Peptide Antibodies in a North American Native Population with Rheumatoid Arthritis and Their First-degree Relatives

Objective.

To determine the prevalence of anti-cyclic citrullinated peptide (anti-CCP) antibodies in unaffected relatives of North American Native probands with rheumatoid arthritis (RA); and the associations of the shared epitope (SE) and HLA-DRB1*0901 with RA and anti-CCP antibodies.

Methods.

The subjects were RA probands, affected relatives, unaffected first-degree (FDR) and more distant relatives, and unaffected controls from the same population. HLA-DRB1 typing was determined by DNA sequencing and anti-CCP antibodies were determined by ELISA.

Results.

DRB1*0901, SE, and SE/DRB1*0901 genotypes were all associated with RA. SE/DRB1*0901, but not other SE genotypes, was associated with disease onset at age < 16 years. The frequency of anti-CCP antibodies was 82% in RA probands, 17% in FDR, 11% in more distant relatives, and 3% in controls. Among unaffected relatives, a significant increased risk of anti-CCP was associated with SE/DRB1*0901 genotype, but not with SE.

Conclusion.

An independent association of the non-SE allele DRB1*0901 with RA was confirmed in this population, and this allele in combination with a SE allele was associated with younger age at disease onset. FDR of RA probands have a higher prevalence of anti-CCP antibodies than more distant relatives and unrelated controls, suggesting a gradient of risk for disease development. Immunogenetic risks may act early in disease pathogenesis at the level of initiation of RA autoantibody formation; however, it is not clear what additional genetic and environmental risks are involved in progression to clinical disease.

High prevalence of rheumatoid factor associated with clinical manifestations of rheumatic disease in Kaingang and Guarani Indians from Southern Brazil

The aim of the present study was to perform a screening for rheumatoid factor (RF) and anti-nuclear antibody in Kaingang, Guarani and Mestizos individuals from Mangueirinha Reservation, State of Paraná, Brazil, and associate it with demographic and clinical data. Serum samples from 321 aborigines (125 male and 196 female; 4-86 years old) and 180 non-Indians healthy individuals were analysed (62 male and 118 female; 2-81 years old). Antinuclear antibody (ANA) was tested by indirect immunofluorescence, and RF by agglutination in latex and turbidimetry. RF was higher in Kaingang when compared to Guarani (P = 0.009), Mestizos (P = 0.061) and non-Indians (P = 0.010). A significant increase of RF was observed in Kaingang women versus Kaingang men (P = 0.002) and, among the women, in Kaingang when compared to Mestizos and Guarani (P <or= 0.008). The positivity for ANA did not show significant differences between the groups. Clinical evaluation of RF positive individuals (n = 6) confirmed rheumatoid arthritis in two Kaingang Indians. Other two individuals (RF positive) will be under medical observation, as well as two Mestizos. The differences observed among the investigated groups, suggest the influence of genetic and hormonal factors in the development of auto antibodies in these populations.

Amerindian ancestry in Argentina is associated with increased risk for systemic lupus erythematosus

Previous studies have demonstrated that in admixed populations, West African ancestry is associated with an increased prevalence of systemic lupus erythematosus (SLE). In the current study, the effect of Amerindian ancestry in SLE was examined in an admixed population in Argentina. The Argentine population is predominantly European with approximately 20% Amerindian admixture, and a very small (<2%) contribution from West Africa. The results indicate that Amerindian admixture in this population is associated with a substantial increase in SLE susceptibility risk (Odds Ratio=7.94, P=0.00006). This difference was not due to known demographic factors, including site of collection, age and gender. In addition, there were trends towards significance for Amerindian ancestry influencing renal disease, age of onset and anti-SSA antibodies. These studies suggest that populations with Amerindian admixture, like those with West African admixture, should be considered in future studies to identify additional allelic variants that predispose to SLE.

Smoking is a strong risk factor for rheumatoid nodules in early rheumatoid arthritis

OBJECTIVE

To examine whether smoking is a risk factor for rheumatoid nodules in early rheumatoid arthritis, and if so to determine the quantitative effect of smoking.

METHODS

From a cohort (n = 1589) in a structured programme for follow up of newly diagnosed cases of rheumatoid arthritis (symptoms of swollen joints < or =12 months), 112 individuals with rheumatoid nodules at inclusion were identified. Nodular patients were each compared with two age and sex matched controls without nodules from the same cohort. A detailed self administered tobacco use questionnaire was answered by 210 patients (63%).

RESULTS

Seventy patients were current smokers, 71 former smokers, and 69 had never smoked. Current smoking and former smoking were more common in patients with rheumatoid nodules compared with controls (86% v 59%) in both sexes. Positive rheumatoid factor (RF) was found more often among cases with nodules than controls (78% v 64%). Using detailed information from the questionnaires with conditional logistic regression analyses, ever having smoked was associated with an increased risk of the presence of rheumatoid nodules (odds ratio (OR) = 7.3 (95% confidence interval, 2.3 to 23.6); p = 0.001). The risk of having nodules was not obviously dose dependent when smoking duration as well as smoking amount were examined. A stratified analysis showed that only RF positive smokers had an increased risk of rheumatoid nodules. Smoking was associated with rheumatoid nodules among both men (p = 0.006) and women (p = 0.001). Tobacco use other than smoking (n = 31) was not associated with an increased risk of nodules (OR = 0.8 (0.2 to 3.4); p = 0.813).

CONCLUSIONS

There is a strong association between smoking and rheumatoid nodules in early seropositive rheumatoid arthritis.

Rheumatoid arthritis in American Indians and Alaska Natives: a review of the literature

BACKGROUND AND OBJECTIVES

An increased prevalence of rheumatoid arthritis (RA) has been reported in several American Indian and Alaska Native (AI/AN) populations. This article reviews the prevalence of RA in these populations, including clinical and serologic features.

METHODS

References were taken from Medline through November 2003, in addition to the Arctic Health Literature Database and the American Indian and Alaska Native Health Bibliography.

RESULTS

Published articles reveal an increased prevalence of RA in the Tlingit, Yakima, Pima, and Chippewa Indians. Clinically the disease in these groups is often severe, with early age of onset, high frequency of radiographic erosions, rheumatoid nodules, and positive rheumatoid factor. Studies of HLA alleles in cases and controls have found a high frequency of HLA DRB1*1402.

CONCLUSIONS

The increased prevalence of RA and more severe disease in specific AI/AN populations suggest an important genetic influence on the development of RA in AI/AN populations. A high frequency of specific high-risk HLA alleles in these populations may account for some of the increased risk, but other genetic factors are likely to contribute. Environmental factors have not been studied in detail, but may also play an important role.

RELEVANCE

Understanding the patterns and burden of disease in AI/AN populations may contribute to understanding the etiology of RA and to the development of preventive strategies.

Epidemiology of extra-articular manifestations in rheumatoid arthritis

Extra-articular RA (ExRA) includes a wide variety of disease manifestations. Although rheumatologists in general are aware that such events are clinically important, the heterogeneity of available data, including discrepancies in case definitions, has complicated constructive discussions on this aspect of the RA disease phenotype. In recent years, there has been a growing recognition of the importance of co-morbidity in patients with RA. ExRA manifestations are not uncommon, explain excess mortality in RA and are predicted by smoking and autoantibodies. Further studies of the mechanisms underlying these associations are likely to be important in improving our understanding of the systemic nature of RA. This article discusses the methodological issues involved in the study of ExRA manifestations, presents suggested criteria that have been used in clinical studies, and reviews important surveys of the epidemiology of extra-articular RA.

Individual factors and musculoskeletal disorders: a framework for their consideration

Individual factors have been variously defined as non-work, demographic, physiological or psychological factors. They may represent a variety of important constructs at different relevant levels that may not be initially evident in their measurement. These include: work-related factors e.g., job assignment, duration of exposure, work style, anthropometric mismatches, and differential responses to job demands; concomitant external or internal exposures e.g., sports, smoking, and endogenous hormones; and physical, psychological and social vulnerabilities e.g., prior injury, depression, socio-economic status. Such factors operate in different ways in the development, course and response to interventions of musculoskeletal disorders. Newer framings of their contribution to musculoskeletal disorders are providing new insights into the role of such factors as some among many which contribute to the burden of MSK disorders in working age populations. As researchers, practitioners and policy makers, we need to consider them in order to reduce burden, to protect the vulnerable and to match interventions to different groups of people most appropriately.

The epidemiology of rheumatoid arthritis

Studies of the descriptive epidemiology of RA indicate a population prevalence of 0.5% to 1% and a highly variable annual incidence (12-1200 per 100,000 population) depending on gender, race/ethnicity, and calendar year. Secular trends in RA incidence over time have been shown in several studies, supporting the hypothesis of a host-environment interaction. People with RA have a significantly increased risk of death compared with age- and sex-matched controls without RA from the same community. The determinants of this excess mortality remain unclear; however, reports suggest increased risk from gastrointestinal, respiratory, cardiovascular, infectious, and hematologic diseases among RA patients compared with controls. Despite extensive epidemiologic research, the etiology of RA is unknown. Several risk factors have been suggested as important in the development or progression of RA. These include genetics, infectious agents, oral contraceptives, smoking, and formal education. Epidemiologic research is an essential contributor to our understanding of RA.

An autoantibody targeting glycated IgG is associated with elevated serum immune complexes in rheumatoid arthritis (RA)

Advanced glycation end-products (AGE) play a role in diabetes complications and in RA. An autoantibody to IgG-AGE has been shown to correlate with RA disease activity. Thus we sought to analyse serum immune complexes (IC) and AGE-modified proteins in Caucasians and North American Indians to see if the presence of anti-IgG-AGE influenced their composition. Polyethylene glycol precipitation of IC from the serum of anti-IgG-AGE-positive or -negative RA patients, and healthy and diabetic controls were examined. Concentrations of circulating IC were highest in anti-IgG-AGE+ RA patients, followed by anti-IgG-AGE- RA patients, which were greater than healthy controls. IC amounts in the Ojibwe were consistently higher than in Caucasians. Affinity purification of AGE-modified proteins from IC and immunoblotting with antibodies against Ig gamma and mu heavy chains, kappa and lambda light chains, and AGE Nepsilon(carboxymethyl)lysine and imidazolone yielded similar results: anti-AGE+ RA patients had elevated levels relative to those without the autoantibody. Levels in both RA groups were higher than in controls. Glycated albumin amounts followed a similar distribution, but were not influenced by the presence of anti-AGE antibodies. A heavily glycated kappa-chain was present primarily in IC from anti-IgG-AGE+ patients. These studies indicate that anti-AGE antibodies have a direct impact on the accumulation of IgG-AGE but not glycated albumin, and may block the normal clearance of IgG-AGE through AGE receptors.

Risk for rheumatic disease in relation to ethnicity and admixture

Risk of systemic lupus erythematosus (SLE) is high in west Africans compared with Europeans, and risk of rheumatoid arthritis (RA) is high in Native Americans compared with Europeans. These differences are not accounted for by differences in allele or haplotype frequencies in the human leucocyte antigen (HLA) region or any other loci known to influence risk of rheumatic disease. Where there has been admixture between two or more ethnic groups that differ in risk of disease, studies of the relationship of disease risk to proportionate admixture can help to distinguish between genetic and environmental explanations for ethnic differences in disease risk and to map the genes underlying these differences.

Genealogy construction in a historically isolated population: application to genetic studies of rheumatoid arthritis in the Pima Indian

PURPOSE

Due to the characteristics of complex traits, many traits may not be amenable to traditional epidemiologic methods. We illustrate an approach that defines an isolated population as the "unit" for carrying out studies of complex disease. We provide an example using the Pima Indians, a relatively isolated population, in which the incidence and prevalence of Type 2 diabetes, gallbladder disease, and rheumatoid arthritis (RA) are significantly increased compared with the general U.S. population. A previous study of RA in the Pima utilizing traditional methods failed to detect a genetic effect on the occurrence of the disease.

METHODS

Our approach involved constructing a genealogy for this population and using a genealogic index to investigate familial aggregation. We developed an algorithm to identify biological relationships among 88 RA cases versus 4,000 subsamples of age-matched individuals from the same population. Kinship coefficients were calculated for all possible pairs of RA cases, and similarly for the subsamples.

RESULTS

The sum of the kinship coefficient among all combination of RA pairs, 5.92, was significantly higher than the average of the 4,000 subsamples, 1.99 (p < 0.001), and was elevated over that of the subsamples to the level of second cousin, supporting a genetic effect in the familial aggregation. The mean inbreeding coefficient for the Pima was 0.00009, similar to that reported for other populations; none of the RA cases were inbred.

CONCLUSIONS

The Pima genealogy can be anticipated to provide valuable information for the genetic study of diseases other than RA. Defining an isolated population as the "unit" in which to assess familial aggregation may be advantageous, especially if there are a limited number of cases in the study population.

Rheumatic diseases in North America's indigenous peoples

OBJECTIVES

There are at least 3 million North American Indians and Eskimos in North America. The epidemiology of rheumatic diseases in Native North Americans differs from that described for the remainder of the North American population. An enhanced understanding of rheumatic diseases in these indigenous people may provide valuable clues to the cause of these disorders and improve rheumatologic care.

METHODS

The world literature was searched for all reports of rheumatic diseases in North American Indians and Eskimos. The reports were reviewed and the findings summarized by disease process.

RESULTS

Many Native American groups have high prevalence rates of rheumatoid arthritis (RA), systemic lupus erythematosus, connective tissue diseases, and spondyloarthropathies. There appears to be a correlation between the pattern of rheumatic diseases in Native North Americans and the patterns of migration and ancestry. In general, Amerind Indians have increased rates of RA and connective tissue disease, while Na-Dene Indians and Eskimos have high rates of spondyloarthropathies. The RA seen in Native Americans is generally severe, seropositive, with an early age of onset, and frequent extraarticular manifestations. Many Native American groups have very high frequencies of the RA shared epitope. The majority of Native American and Eskimo groups also have high frequencies of HLA-B27, and some of the world's highest prevalence rates of spondyloarthropathies are described in these groups. Although some groups show a marked tendency to develop either Reiter's syndrome or ankylosing spondylitis, psoriatic and enteropathic arthritis are rare.

CONCLUSIONS

The excess rheumatic disease seen in this population is most likely genetic in origin. Because of the combination of high rates of rheumatic disease and relative genetic homogeneity, Native North Americans represent a singular opportunity to study genetic contributions to rheumatic disease. For clinicians, the index of suspicion for rheumatic diseases in North American Indians and Eskimos should be high, and the severe disease and sometimes atypical presentations kept in mind.