Body Fat Percentage, Waist Circumference, and Obesity As Risk Factors for Rheumatoid Arthritis: A Danish Cohort Study

Genetic causality between modifiable risk factors and the risk of rheumatoid arthritis: Evidence from Mendelian randomization

OBJECTIVES

Emerging research has investigated the potential impact of several modifiable risk factors on the risks of rheumatoid arthritis (RA), but the findings did not yield consistent results. This study aimed to comprehensively explore the genetic causality between modifiable risk factors and the susceptibility of RA risk using the Mendelian randomization (MR) approach.

METHODS

Genetic instruments for modifiable risk factors were selected from several genome-wide association studies at the genome-wide significance level (p < 5 × 10-8), respectively. Summary-level data for RA were sourced from a comprehensive meta-analysis. The causal estimates linking modifiable risk factors to RA risk were assessed using MR analysis with inverse variance weighting (IVW), MR-Egger, weighted, and weighted median methods.

RESULTS

After Bonferroni correction for multiple tests, we found the presence of causality between educational attainment and RA, where there were protective effects of educational attainment (college completion) (odds ratio [OR] = 0.50, 95% CI = 0.36, 0.69, p = 2.87E-05) and educational attainment (years of education) (OR = 0.93, 95% CI = 0.90, 0.96, p = 4.18E-06) on the lower RA risks. Nevertheless, smoking initiation was observed to be associated with increased RA risks (OR = 1.27, 95% CI = 1.09, 1.47, p = .002). Moreover, there was no indication of horizontal pleiotropy of genetic variants during causal inference between modifiable risk factors and RA.

CONCLUSIONS

Our study reveals the genetic causal impacts of educational attainment and smoking on RA risks, suggesting that the early monitoring and recognition of modifiable risk factors would be beneficial for the preventive counseling/treatment strategies for RA.

Joint Damage and Low Lean Body Mass in a Cohort of Peruvian Patients With Rheumatoid Arthritis

OBJECTIVES

To determine the association between radiologic joint damage (JD) and a lower lean body mass (LBM) in rheumatoid arthritis (RA) patients.

METHODS

A cross-sectional study from a single center established RA cohort. JD and appendicular LBM (arms and legs) were measured with the Sharp/van der Heijde (SvdH) score and dual x-ray absorptiometry expressed as kg/m 2 , respectively. A univariable analysis was used to determine the association between JD an LBM; then, a multivariable regression model was performed to evaluate the persistence of this association, adjusted by age, gender, disease duration, socioeconomic status (by the Graffar method), tobacco use, anticitrullinated protein antibody levels, Disease Activity Score in 28 joints for RA with erythrocyte sedimentation rate, glucocorticoid use (as prednisone equivalent), disease-modifying antirheumatic drug use, body mass index, and disability (by the multidimensional Health Assessment Questionnaire).

RESULTS

Two hundred forty-seven patients were included; the average (SD) age was 63.0 (12.8) years, disease duration 20 (15.00) years, the total SvdH was 66 (86.75), and the aLBM was 13.6 (3.82) kg/m 2 . In the univariable analysis, a lower appendicular LBM was associated with higher SvdH score on the female population, in terms of the total ( B = -8.6, p < 0.01), bone erosion (-4.4, p < 0.01), and joint space narrowing (-4.2, p < 0.01) scores; this correlation remained in the multivariable analysis in terms of total SvdH ( B = -9.5, p < 0.01), bone erosion (-5.2, p < 0.01), and joint space narrowing (-4.3, p < 0.01).

CONCLUSIONS

A lower LBM in female patients was associated with more severe JD independently of other variables examined. Strategies aimed at preserving LBM could have a favorable impact on the course of disease.

Decreased Serum CTRP3 level was associated with connective tissue diseases

Objective

Complement C1q tumor necrosis factor-related protein 3 (CTRP3) and 9 (CTRP9) are two of the most extensively studied adipokines, known for their diverse biological functions. However, it remains unclear whether serum levels of CTRP3 or CTRP9 are associated with connective tissue diseases (CTD).

Methods

Serum CTRP3 and CTRP9 levels were measured by enzyme-linked immune sorbent assay (ELISA) and analyzed in patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), primary Sjogren's syndrome (pSS), ankylosing spondylitis (AS), undifferentiated connective tissue disease (UCTD), as well as in healthy controls (HCs).

Results

Serum CTRP3 levels were all significantly lower in patients with RA, SLE, pSS and AS compared with HCs. However, there were no significant differences in serum CTRP9 levels between patients with RA, SLE, pSS, or AS and HCs. In pSS patients, CTRP3 showed a weak correlation with blood glucose, creatinine, and urine acid in pSS patients, while no correlations were observed between serum CTRP3 levels and clinical or laboratory indices in RA, SLE or AS patients. Stable associations between CTRP3 and RA, SLE, pSS and AS were evaluated using multivariate logistics regression analysis. Receiver operating characteristic (ROC) curves were plotted to evaluated CTRP3 as a marker for RA, SLE, pSS and AS, yielding area under curve (AUC) values of 0.691, 0.727, 0.658 and 0.694, respectively.

Conclusion

Decreased serum CTRP3 levels were associated with RA, SLE, pSS and AS.

Prevalence and contributing factors of metabolic syndrome in rheumatoid arthritis patients

BACKGROUND

Promoting prevalence of metabolic syndrome (MetS) in Rheumatoid arthritis (RA) patients might occur secondary to RA therapy as well as sedentary life style. However, conflicting observations have been reported on the correlation between MetS and RA. This study aimed to determine the frequency of MetS and association of its components in RA.

METHODS

In this study, 500 RA patients and 500 age- and gender-matched healthy controls were enrolled. MetS was fulfilled through the International Diabetes Federation (IDF) criteria. A multivariate regression model was used to control for variables independently associated with the risk of MetS in RA patients.

RESULTS

The prevalence of MetS was 58.8% on IDF criteria in RA patients that was higher than controls (20.4%). Higher incidence of cardiovascular disease (CVD), the familial history of CVD, hypertension, type 2 diabetes mellitus (T2DM), smoking, dyslipidemia, and higher levels of body mass index (BMI), waist circumference (WC), total cholesterol level, fasting blood sugar (FBS), triglyceride (TG) level, low-density lipoprotein (LDL) level, while lower levels of high-density lipoprotein (HDL) were associated with an increased risk of MetS in RA patients. Multivariate regression analysis indicated that age, WC, dyslipidemia, LDL, and DAS28 were independent predictors of MetS in the RA patients.

CONCLUSIONS

The prevalence of MetS is higher in RA patients. Our findings suggest an association between cardiovascular risk factors and the increased prevalence of MetS in RA patients.

Metabolic Syndrome Is Associated With an Increased Risk of Rheumatoid Arthritis: A Prospective Cohort Study Including 369,065 Participants

OBJECTIVE

To explore the associations between metabolic syndrome (MetS) and its individual components and the risk of rheumatoid arthritis (RA).

METHODS

A total of 369,065 individuals were included in the present study based on the UK Biobank. Multivariable Cox proportional hazards regression models were applied to estimate the associations between MetS and its individual components and the risk of RA. Mediation analysis was performed to further assess the potential mediating role of C-reactive protein (CRP) in the relationship between MetS and RA.

RESULTS

During a median follow-up period of 12.04 years, a total of 4901 incident RA cases were documented. MetS (hazard ratio [HR] 1.22, 95% CI 1.14-1.30) and 4 of its 5 components (elevated waist circumference [WC; HR 1.21, 95% CI 1.12-1.32], elevated triglyceride [TG] level [HR 1.12, 95% CI 1.05-1.19], reduced high-density lipoprotein cholesterol [HDL-C] level [HR 1.31, 95% CI 1.23-1.39], and hyperglycemia [HR 1.15, 95% CI 1.05-1.25]) were associated with an increased risk of RA. In addition, the risk of RA increased as the number of diagnosed MetS components increased, with the highest risk in participants with all 5 components. Mediation analysis showed that CRP might mediate the association between MetS and RA, accounting for 9.27% of the total effect.

CONCLUSION

These findings indicated positive associations between MetS and 4 of its components (WC, TG, HDL-C, and hyperglycemia) and the risk of RA, highlighting the importance of MetS management in the prevention of RA.

Integrative non-pharmacological care for individuals at risk of rheumatoid arthritis

There is increasing knowledge in the recognition of individuals at risk for progression to rheumatoid arthritis (RA) before the clinical manifestation of the disease. This prodromal phase preceding the manifestation of RA may represent a "window of opportunity" for preventive interventions that may transform the clinical approach to this disease. However, limited evidence exists in support of effective interventions to delay the onset or even halt the manifestation of RA. Given the multifactorial nature of RA development and disease progression, the latest guidelines for established RA stress the use of integrative interventions and multidisciplinary care strategies, combining pharmacologic treatment with non-pharmacological approaches. Accordingly, individuals at risk of RA could be offered an integrative, multifactorial intervention approach. Current data point toward pharmacological intervention reverting the subclinical inflammation and delay in the disease onset. In addition, targeting life style modifiable factors (smoking cessation, dental health, physical activity, and diet) may presumably improve RA prognosis in individuals at risk, mainly by changes in epigenetics, autoantibodies, cytokines profiles, and microbiome. Nonetheless, the benefits of multidisciplinary interventions to halt the manifestation of RA in at-risk individuals remain unknown. As there is a growing knowledge of possible pharmacological intervention in the preclinical phase, this narrative review aims to provide a comprehensive overview of non-pharmacological treatments in individuals at risk of RA. Considering the mechanisms preceding the clinical manifestation of RA we explored all aspects that would be worth modifying and that would represent an integrative non-pharmacological care for individuals at risk of RA.

Effect of bariatric and metabolic surgery on rheumatoid arthritis outcomes: A systematic review

INTRODUCTION

Obesity is a growing and debilitating epidemic worldwide that is associated with an increased inflammation. It is often linked to rheumatic diseases and may impact negatively their natural history. The use of bariatric and metabolic surgery (BMS) has increased thanks to its positive effect on major comorbidities like diabetes type 2. This systematic review provides the most up-to-date published literature regarding the effect of BMS on outcomes in rheumatoid arthritis.

METHODS

This systematic review followed the preferred reporting items for systematic reviews guidelines. Original articles from Pubmed, Embase and Cochrane, published until June 16th 2023, and tackling the effect of BMS on disease outcomes in patients with RA were included.

RESULTS

Three studies met the inclusion criteria. They were published between 2015 and 2022. The total number of RA patients was 33193 and 6700 of them underwent BMS. Compared to non-surgical patients, weight loss after BMS was associated with lower disease activity outcomes at 12 months (p<0.05). Similarly, prior BMS in RA patients was significantly associated with reduced odds ratios for all the morbidities and in-hospital mortality compared with no prior BMS (36.5% vs 54.6%, OR = 0.45, 95% CI (0.42, 0.48), p< 0.001) and (0.4% vs 0.9%, OR = 0.41, 95% CI (0.27-0.61), p < 0.001) respectively.

CONCLUSION

To conclude, published data indicate that BMS seems a promising alternative in reducing RA disease activity as well as morbidity and mortality in patients with obesity.

Adipokines in Rheumatoid Arthritis: Emerging Biomarkers and Therapeutic Targets

Rheumatoid arthritis (RA) is a chronic inflammatory disease manifested by joint involvement, extra-articular manifestations, and general symptoms. Adipose tissue, previously perceived as an inert energy storage organ, has been recognised as a significant contributor to RA pathophysiology. Adipokines modulate immune responses, inflammation, and metabolic pathways in RA. Although most adipokines have a pro-inflammatory and aggravating effect on RA, some could counteract this pathological process. The coexistence of RA and sarcopenic obesity (SO) has gained attention due to its impact on disease severity and outcomes. Sarcopenic obesity further contributes to the inflammatory milieu and metabolic disturbances. Recent research has highlighted the intricate crosstalk between adipose tissue and skeletal muscle, suggesting potential interactions between these tissues in RA. This review summarizes the roles of adipokines in RA, particularly in inflammation, immune modulation, and joint destruction. In addition, it explores the emerging role of adipomyokines, specifically irisin and myostatin, in the pathogenesis of RA and their potential as therapeutic targets. We discuss the therapeutic implications of targeting adipokines and adipomyokines in RA management and highlight the challenges and future directions for research in this field.

A New Approach Using BMI and FMI as Predictors of Cardio-Vascular Risk Factors among Mexican Young Adults

The study aimed to identify accurate cut-off points for waist circumference (WC), body fat percentage (BF%), body mass index (BMI), fat mass index (FMI), and fat-free mass index (FFMI), and to determine their effective accuracy to predict cardiovascular risk factors (CVRFs) among Mexican young adults. A cross-sectional study was conducted among 1730 Mexican young adults. Adiposity measures and CVRFs were assessed under fasting conditions. The optimal cut-off points were assessed using the receiver operating characteristic curve (ROC). Age-adjusted odds ratios (OR) were used to assess the associations between anthropometric measurements and CVRFs. The cut-off values found, in females and males, respectively, for high WC (≥72.3 and ≥84.9), high BF% (≥30 and ≥22.6), high BMI (≥23.7 and ≥24.4), high FMI (≥7.1 and ≥5.5), and low FFMI (≤16 and ≤18.9) differ from those set by current guidelines. High BMI in women, and high FMI in men, assessed by the 50th percentile, had the best discriminatory power in detecting CVRFs, especially high triglycerides (OR: 3.07, CI: 2.21-4.27 and OR: 3.05, CI: 2.28-4.08, respectively). Therefore, these results suggest that BMI and FMI measures should be used to improve the screening of CVRFs in Mexican young adults.

Appraising causal risk and protective factors for rheumatoid arthritis

Aims

Mendelian randomization (MR) is considered to overcome the bias of observational studies, but there is no current meta-analysis of MR studies on rheumatoid arthritis (RA). The purpose of this study was to summarize the relationship between potential pathogenic factors and RA risk based on existing MR studies.

Methods

PubMed, Web of Science, and Embase were searched for MR studies on influencing factors in relation to RA up to October 2022. Meta-analyses of MR studies assessing correlations between various potential pathogenic factors and RA were conducted. Random-effect and fixed-effect models were used to synthesize the odds ratios of various pathogenic factors and RA. The quality of the study was assessed using the Strengthening the Reporting of Observational Studies in Epidemiology using Mendelian Randomization (STROBE-MR) guidelines.

Results

A total of 517 potentially relevant articles were screened, 35 studies were included in the systematic review, and 19 studies were eligible to be included in the meta-analysis. Pooled estimates of 19 included studies (causality between 15 different risk factors and RA) revealed that obesity, smoking, coffee intake, lower education attainment, and Graves' disease (GD) were related to the increased risk of RA. In contrast, the causality contribution from serum mineral levels (calcium, iron, copper, zinc, magnesium, selenium), alcohol intake, and chronic periodontitis to RA is not significant.

Conclusion

Obesity, smoking, education attainment, and GD have real causal effects on the occurrence and development of RA. These results may provide insights into the genetic susceptibility and potential biological pathways of RA.

Modifiable risk factors linked to the development of rheumatoid arthritis: evidence, immunological mechanisms and prevention

Rheumatoid Arthritis (RA) is a common autoimmune disease that targets the synovial joints leading to arthritis. Although the etiology of RA remains largely unknown, it is clear that numerous modifiable risk factors confer increased risk to developing RA. Of these risk factors, cigarette smoking, nutrition, obesity, occupational exposures and periodontal disease all incrementally increase RA risk. However, the precise immunological mechanisms by which these risk factors lead to RA are not well understood. Basic and translational studies have provided key insights into the relationship between inflammation, antibody production and the influence in other key cellular events such as T cell polarization in RA risk. Improving our general understanding of the mechanisms which lead to RA will help identify targets for prevention trials, which are underway in at-risk populations. Herein, we review the modifiable risk factors that are linked to RA development and describe immune mechanisms that may be involved. We highlight the few studies that have sought to understand if modification of these risk factors reduces RA risk. Finally, we speculate that modification of risk factors may be an appealing avenue for prevention for some at-risk individuals, specifically those who prefer lifestyle interventions due to safety and economic reasons.

Adiposity is associated with expansion of the genus Dialister in rheumatoid arthritis patients

OBJECTIVE

To analyze the intestinal microbiota of patients with rheumatoid arthritis (RA) and obesity and a higher percentage of fatty tissue.

METHODS

Nested case-control study of 80 RA patients and 80 age and sex-matched controls. Obesity was defined as a body mass index ≥ 30, and body composition using dual-energy x-ray absorptiometry. The gut microbiota was analyzed using 16 S rRNA gene sequencing; bioinformatics analysis was performed using QIIME2 and PICRUSt. Other variables included averaged 28-joint Disease Activity Score (DAS28-ESR), cytokines and adipokines. Two multivariate were constructed with obesity and fat mass index (FMI).

RESULTS

Obesity was more frequent in RA patients than in controls (36.3 % vs 25.1 %; p = 0.026), as was a higher FMI value (mean [SE]=11.6 [3.9] vs 10.2 [3.9]; p = 0.032). Alpha and beta diversity analysis revealed differences in gut microbiota between RA patients with and without obesity. Dialister and Odoribacter were more abundant in RA patients with obesity than in RA patients without obesity, while the genus Clostridium was more abundant in RA patients without obesity. The factors associated with obesity in RA patients were age (OR [95 % CI], 1.09 [1.02-1.17]), mean DAS28-ESR (OR [95 % CI], 1.46 [1.12-1.67]), leptin levels (OR [95 % CI], 1.06 [1.01-1.10]), the genus Dialister (OR [95 % CI], 1.03 [1.01-1.07]), and the genus Clostridium (OR [95 % CI], 0.013 [0.00-0.36]). The associations observed for FMI were similar.

CONCLUSIONS

In patients with RA, obesity, and a higher percentage of fatty tissue, intestinal microbiota differed from that of controls and of the other patients. The genus Dialister was associated with obesity and FMI.

Cardiovascular Disease and Cardiac Imaging in Inflammatory Arthritis

Cardiovascular morbidity and mortality are more prevalent in inflammatory arthritis (IA) compared to the general population. Recognizing the importance of addressing this issue, the European League Against Rheumatism (EULAR) published guidelines on cardiovascular disease (CVD) risk management in IA in 2016, with plans to update going forward based on the latest emerging evidence. Herein we review the latest evidence on cardiovascular disease in IA, taking a focus on rheumatoid arthritis, psoriatic arthritis, and axial spondylarthritis, reflecting on the scale of the problem and imaging modalities to identify disease. Evidence demonstrates that both traditional CVD factors and inflammation contribute to the higher CVD burden. Whereas CVD has decreased with the newer anti-rheumatic treatments currently available, CVD continues to remain an important comorbidity in IA patients calling for prompt screening and management of CVD and related risk factors. Non-invasive cardiovascular imaging has been attracting much attention in view of the possibility of detecting cardiovascular lesions in IA accurately and promptly, even at the pre-clinical stage. We reflect on imaging modalities to screen for CVD in IA and on the important role of rheumatologists and cardiologists working closely together.

Progression of pre-rheumatoid arthritis to clinical disease of joints: Potential role of mesenchymal stem cells

Rheumatoid arthritis (RA) related autoimmunity is developed at mucosal sites due to the interplay between genetic risk factors and environmental triggers. The pre-RA phase that leads to anti-citrullinated protein antibodies, rheumatoid factor, and other autoantibodies spread in the systemic circulation may not affect articular tissue for years until a mysterious second hit triggers the localization of RA-related autoimmunity in joints. Several players in the joint microenvironment mediate the synovial innate and adaptive immunological processes, eventually leading to clinical synovitis. There still exists a gap in the early phase of RA pathogenesis, i.e., the progression of diseases from the systemic circulation to joints. The lack of better understanding of these events results in the inability to answer questions about why only after a certain point of time the disease appears in joints and why in some cases, it simply remains latent and doesn't affect joints at all. In the current review, we focused on the immunomodulatory and regenerative role of mesenchymal stem cells and associated exosomes in RA pathology. We also highlighted the age-related dysregulations in activities of mesenchymal stem cells and how that might trigger homing of systemic autoimmunity to joints.

Association between work physical activity, dietary factors, and risk of rheumatoid arthritis

OBJECTIVE

We aimed to determine the association of physical activity and dietary factors on RA risk.

METHODS

This case-control study within the Mayo Clinic Biobank matched incident RA cases (two codes plus disease-modifying anti-rheumatic drug, PPV 95%) to controls 1:3 on age, sex, and recruitment year/location. A baseline questionnaire assessed activity and dietary exposures. Logistic regression models calculated adjusted odds ratios (aOR) with 95% confidence intervals (CI) of RA for each of 45 activity/dietary exposures.

RESULTS

We identified 212 incident RA cases and 636 controls (mean age 64, 70% female). Active work physical activity was associated with elevated risk of RA (aOR 3.00, 95% CI 1.58-5.69 vs. sedentary); leisure activity was not (aOR 0.96, 95% CI 0.64-1.42 sedentary vs. active). Three or more servings high-fat food and 5+ servings fruits/vegetables daily showed non-significant associations with RA (aOR 1.22, 95% CI 0.74-2.00 vs. 0-1 time; aOR 0.75, 95% CI 0.51-1.11 vs. 0-3 times), especially in sensitivity analyses with at least five years between questionnaire and RA (aOR 1.80, 95% CI 0.69-4.71; aOR 0.54, 95% CI 0.27-1.08). Alcohol binging was not associated with RA risk (aOR 1.28, 95% CI 0.56-2.96). Finally, sensitivity (versus primary) analyses showed a nonsignificant increase in RA risk for most vitamins and supplements.

CONCLUSION

Active work physical activity and some nutritional profiles (increased high-fat, reduced fruit/vegetable consumption) may be associated with increased risk of RA. Confirmatory studies are needed.

Epidemiologic Opportunities and Challenges in Studying Environmental Risk Factors for Rheumatic Diseases

Most rheumatic diseases have a stronger environmental than hereditary etiology. This article summarizes the key environmental risk factors for rheumatic diseases, the data sources that generated these findings, and the key pitfalls with existing research that every rheumatology clinician should know. Emerging research opportunities hold promise to revolutionize this field, and soon.

Lifestyle, Hormonal, and Metabolic Environmental Risks for Rheumatoid Arthritis

Although there is a substantial body of literature focused on understanding noninhalational risk-factors for rheumatoid arthritis, the data are mixed and often conflicting. Given the other health benefits for certain lifestyle modifications, it seems reasonable for clinicians to promote healthy lifestyle habits related to diet, exercise, maintenance of health weight, and maintenance of good dental hygiene. Overall, however, these lifestyle modifications may be expected to have modest benefit, and other strategies to prevent rheumatoid arthritis in high-risk patients are needed.

The Association of Waist Circumference with the Prevalence and Survival of Digestive Tract Cancer in US Adults: A Population Study Based on Machine Learning Methods

Aims

This paper aims to investigate the relationship of waist circumference (WC) with digestive tract cancer morbidity and mortality.

Methods

Based on the data from a nationally representative US population survey, we summarized the prevalence of digestive tract cancer and all-cause mortality of cancer patients across WC quartiles. Adjusted logistic regression and restricted spline curve were used to analyze WC and the prevalence of digestive tract cancer. Moreover, Cox regression and the Kaplan-Meier curve were applied to investigate the association of WC with all-cause mortality. We also attempted to make a model to predict cancer happening.

Results

This paper included a total of 34,041 participants, with digestive tract cancer observed in 265 (0.7%) individuals. WC was positively associated with digestive tract cancer morbidity after full adjustment of covariates (OR: 1.72 and 95% CI: 1.41-2.10). Also, individuals in the highest WC group had a higher risk of digestive tract cancer (Q4, OR: 2.71 and 95% CI: 1.48-5.00). Moreover, no significant association was observed in upper digestive cancer, and WC was associated with a longer survival time once diagnosed (hazard ratio (HR): 0.50 and 95% CI: 0.28-0.92). Finally, the model we made proved to be effective.

Conclusion

High WC is a risk factor for digestive tract cancer with or without adjusting for body mass index, especially those located in the lower digestive tract. However, once digestive tract cancer has been diagnosed, patients with higher WC showed better survival outcomes. Moreover, machine learning methods can be used to predict digestive tract cancer risk in the future.

Global epidemiology of rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease that predominantly affects the joints. The prevalence of RA varies globally, with generally a higher prevalence in industrialized countries, which may be explained by exposures to environmental risk factors, but also by genetic factors, differing demographics and under-reporting in other parts of the world. Over the past three decades, strong trends of the declining severity of RA probably reflect changes in treatment paradigms and overall better management of the disease. Other trends include increasing RA prevalence. Common risk factors for RA include both modifiable lifestyle-associated variables and non-modifiable features, such as genetics and sex. A better understanding of the natural history of RA, and of the factors that contribute to the development of RA in specific populations, might lead to the introduction of specific prevention strategies for this debilitating disease.

Anthropometric Measures and Risk of Rheumatoid Arthritis in the French E3N Cohort Study

We aimed to assess the relationships between anthropometric measures and risk of rheumatoid arthritis (RA). The E3N cohort included 98,995 women (aged 40−65 years at the recruitment) who completed mailed questionnaires on reproductive factors, lifestyle, and health-related information, including anthropometric measures, every 2−3 years. Cox proportional hazards regression models with age as the time scale and adjusted on known RA risk factors were used to estimate hazard ratios (HRs) and 95% confidence intervals for the risk of incident RA in the overall population (n = 78,452) and after stratification on smoking exposure. Incident RA diagnosis was validated in 698 women. Abdominal obesity (waist circumference >88 cm) was associated with RA (HR = 1.2 (1.0−1.5)), independent of BMI; whereas obesity, defined as BMI ≥ 30 kg/m2, was marginally associated with RA (HR = 1.26 (0.9−1.5), ptrend = 0.0559). Taking lean body shape (BS) as reference, medium BS at puberty (HR = 1.3 (1.0−1.7)) and medium-large BS at perimenopausal period (HR = 1.5 (1.1−1.9)) were associated with the risk of RA among never-smoker women, independent of BMI. Regarding BS trajectory, taking constantly lean BS as reference, constantly large BS from puberty to perimenopause was associated with RA among non-smokers (HR = 2.10 (1.2−3.6)), independent of BMI.

Physical Fitness Attenuates the Impact of Higher Body Mass and Adiposity on Inflammation in Women With Systemic Lupus Erythematosus

Aims

Higher body mass and adiposity represent independent contributors to the systemic low-grade inflammatory state often observed in patients with systemic lupus erythematosus (SLE). This study assessed the role of physical fitness in the association of body mass and adiposity with inflammation in women with SLE.

Methods

A total of 77 women with SLE were included in this cross-sectional study. We obtained body mass index, waist-to-height ratio, and body fat percentage as indicators of body mass and adiposity. Inflammation was assessed through Serum levels of C-reactive protein, interleukin 6, and leptin. Cardiorespiratory fitness was assessed with the 6-minute walk test, range of motion with the back-scratch test, and muscular strength with handgrip dynamometry.

Results

Cardiorespiratory fitness attenuated the association of both body mass index and body fat percentage with interleukin 6 (all, P<0.05). Range of motion attenuated the association of body mass index with interleukin 6 (P<0.05) and the association of body fat percentage with C-reactive protein (P<0.05). These interactions indicated that higher fitness was associated with a lower increase in inflammation per unit increase of body mass or adiposity. Muscular strength showed a non-significant trend to attenuate the association of body fat percentage with interleukin 6 (P=0.057) but potentiated the association of body fat percentage with leptin (P<0.05).

Conclusion

These findings suggest that higher levels of cardiorespiratory fitness and range of motion might attenuate the impact of higher body mass and adiposity on inflammation in women with SLE. The role of muscular strength requires further investigation.

Intake of marine n-3 polyunsaturated fatty acids and the risk of rheumatoid arthritis: protocol for a cohort study using data from the Danish Diet, Cancer and Health cohort and Danish health registers

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory joint disease with multifactorial aetiology. Smoking is a well-established lifestyle risk factor, but diet may also have an impact on the risk of RA. Intake of the major marine n-3 polyunsaturated fatty acids in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been hypothesised to lower the risk of RA due to their anti-inflammatory effects, although based on limited knowledge. Therefore, we aim to investigate the associations between dietary intake of EPA and DHA and the risk of incident RA.

METHODS AND ANALYSIS

A cohort study. The follow-up design will be based on data from the Danish Diet, Cancer and Health cohort, which was established between 1993 and 1997. The participants will be followed through record linkage using nationwide registers including the Danish Civil Registration System, the Danish National Patient Registry and the Danish National Prescription Registry using the unique Civil Personal Registration number. Time-to-event analyses will be conducted with RA as the outcome of interest. The participants will be followed from inclusion until date of RA diagnosis, death, emigration or end of follow-up. HRs with 95% CIs obtained using Cox proportional hazard regression models, with age as underlying time scale and adjustment for established and potential risk factors, will be used as measures of association.

ETHICS AND DISSEMINATION

The study has been approved by the Data Protection Committee of Northern Jutland, Denmark (2019-87) and the North Denmark Region Committee on Health Research Ethics (N-20190031). Study results will be disseminated through peer-reviewed journals and presentations at international conferences.

Rheumatoid arthritis is a preventable disease: 11 ways to reduce your patients' risk

New evidence shows that up to 40% of rheumatoid arthritis (RA) cases are attributable to exposure to potentially modifiable factors. We can now identify people at higher risk of RA (pre-RA) through their family history, risk factors, autoantibodies and symptoms. Counselling these patients to act to modify factors known to be associated with RA risk could prevent the development of RA, and evidence shows that informing individuals of their risk and of ways to reduce it leads to positive behavioural change and is not harmful. This consumer-focused narrative review is targeted at primary care providers and physicians to describe 11 changes that can be made, based on current evidence linking potentially modifiable factors to RA risk. These evidence-based recommendations are: Cease smoking Reduce exposure to inhaled silica, dusts and occupational risks Maintain a healthy weight Increase leisure time physical activity Maintain good dental hygiene Maximise breastfeeding if able Maximise dietary quality, and avoid high salt diets Consume high levels of Omega-3 fatty acids and fish Reduce consumption of sugar-sweetened soft drinks Consume moderate levels of alcohol Remain Vitamin D replete This article is protected by copyright. All rights reserved.

Birthweight, body size, and growth during childhood and risks of rheumatoid arthritis: a large Danish cohort study

Objectives: Adult obesity may be positively associated with risks of rheumatoid arthritis (RA), but associations with early life body size are unknown. We examined whether birthweight, childhood body mass index (BMI), height, and changes in BMI and height were associated with risks of adult RA.Method: A cohort of 346 602 children (171 127 girls) from the Copenhagen School Health Records Register, born in 1930-1996, with measured weights and heights from 7 to 13 years of age, were included. Information on RA, including serological status, came from national registers from 1977 to 2017. Cox regressions were performed.Results: During a median of 35.1 years of observation time per person, 4991 individuals (3565 women) were registered with RA. Among girls, per BMI z-score, risks of RA and seropositive RA increased by 4-9% and 6-10%, respectively. Girls with overweight had higher risks of RA than girls without overweight. Girls who became overweight by 13 years of age had increased risks of RA compared to girls without overweight at 7 or 13 years (hazard ratio = 1.40, 95% confidence interval 1.19-1.66). For boys, associations between BMI and RA (including seropositive RA) were not statistically significant. Height was not associated with RA (any type) in girls. Taller boys had higher risks of RA, especially seropositive RA. Birthweight was not associated with RA.Conclusions: Among women, childhood adiposity was associated with increased risks of RA. Among men, childhood height was positively associated with risks of RA. These findings support the hypothesis that early life factors may be important in the aetiology of RA.

Urticaria and increased risk of rheumatoid arthritis: a two-sample Mendelian randomisation study in European population

BACKGROUND

In recent years, a growing body of observational studies suggest that urticaria is associated with a higher risk of rheumatoid arthritis (RA). However, the causal association between urticaria and RA remains unknown.

OBJECTIVE

To investigate the causal relationship of urticaria and RA in European populations by Mendelian randomisation (MR) approach.

METHODS

We conducted two-sample MR analyses. Eleven single-nucleotide polymorphisms associated with urticaria were used as instrumental variables. The summary data on urticaria were derived from FinnGen Data Freeze 2. The summary data on RA were obtained from a published meta-analysis using European samples. Four MR methods were applied to the MR estimates. Three heterogeneity tests, including Cochran's Q test, single variant analysis, and leave-one-out variant analysis, were used. The pleiotropy and horizontal pleiotropy among instrumental variables were assessed with MR-Egger regression intercept, MR pleiotropy residual sum and outlier global test, and PhenoScanner.

RESULTS

The MR analysis suggested that urticaria was causally associated with RA (odds ratio = 1.114, 95% confidence interval = 1.024-1.211, p = .011). No genetic pleiotropy or horizontal pleiotropy was revealed by MR-Egger regression intercept and MR pleiotropy residual sum and outlier global test. The sensitivity analysis results were relatively robust.

CONCLUSIONS

The MR analysis suggested there was sufficient evidence to indicate urticaria is the cause of RA.

Adiponectin Associates with Rheumatoid Arthritis Risk in Overweight and Obesity Independently of Other Adipokines

We recently reported that increased serum adiponectin was associated with rheumatoid arthritis (RA) risk in subjects with obesity. We hereby aim to determine if other adipokines associate with RA risk and if the association between adiponectin and RA is independent of other adipokines. Two nested-case control studies were performed in two different cohorts: 82 participants of the Swedish Obese Subjects (SOS) study who developed RA during follow-up matched with 410 controls, and 88 matched pairs from the Medical Biobank of Northern Sweden. Baseline levels of circulating adipokines were measured using ELISA. In a multivariable analysis in the SOS cohort, higher adiponectin was associated with an increased risk of RA independently of other adipokines (OR for RA risk: 1.06, 95% CI: 1.01–1.12, p = 0.02). No association between leptin, resistin, and visfatin levels and the risk of RA was detected. In the cohort from the Medical Biobank of Northern Sweden, higher adiponectin was associated with an increased risk of RA only in participants with overweight/obesity (OR: 1.17, 95% CI: 1.01−1.36, p = 0.03), independently of other adipokines. Our results show that in individuals with overweight/obesity, higher circulating levels of adiponectin, but not leptin, resistin, or visfatin, were associated with an increased RA risk.

Obesity Progression Between Young Adulthood and Midlife and Incident Arthritis: A Retrospective Cohort Study of US Adults

OBJECTIVE

To examine the association between weight change from young adulthood to midlife and the risk of incident arthritis.

METHODS

Using data from the National Health and Nutrition Examination Survey, we categorized participants into weight-change categories based on their recalled weight during young adulthood and midlife. We estimated the association of weight change and developing an arthritis condition over 10 years using adjusted Cox models. Findings were extrapolated to the US population to determine the proportion of incident arthritis cases that could be averted if the entire population maintained a normal body mass index (BMI) in young adulthood and midlife.

RESULTS

Among our sample of adults who were ages 40-69 years at their midlife weight measure (n = 13,669), 3,603 developed an arthritis condition. Compared with adults who maintained a normal-normal BMI, the normal-overweight, normal-obese, overweight-obese, and obese-obese groups had a significantly elevated risk of incident arthritis conditions. The obese-overweight group had a lower risk of incident arthritis conditions compared with the obese-obese group and a comparable risk to the overweight-overweight group. Nearly one-fourth of incident arthritis cases, corresponding to 2.7 million individuals, would have been averted under the hypothetical scenario where all individuals maintained normal weight from young adulthood to midlife.

CONCLUSION

Weight loss from young adulthood to midlife was associated with a substantially reduced risk of developing an arthritis condition. We found no evidence of residual risk from having been heavier earlier in life. Our findings highlight the critical need to expand obesity treatment and prevention to achieve meaningful reductions in the burden of arthritis.

Etiologies of Rheumatoid Arthritis: Update on Mucosal, Genetic, and Cellular Pathogenesis

Purpose of Review

Over the last few years, the scientific community has made significant progress in understanding the etiology of rheumatoid arthritis (RA). In this review, we summarize those key findings and trends.

Recent Findings

New data strongly implicates respiratory exposures, obesity, diet and microbiome, genetics, and their interactions in the etiology of RA. Furthermore, anti-posttranslationally modified protein antibodies (AMPAs) and abnormal glycosylation may be additional biomarkers for RA. Finally, functional genomics techniques implicate loss of certain macrophage populations and proliferation of synovial fibroblasts in RA.

Summary

These findings support the notion that RA originates at mucosal sites, augmented by genetic predisposition, and mediated by certain cell types including macrophages and fibroblasts. Weight loss, physical activity, and diet are additional modifiable factors beyond smoking cessation that can reduce risk of RA. Future epidemiologic and translational studies leveraging multi-omics approaches will help map the precise sequence of events in RA pathogenesis.

Abdominal Obesity in Comparison with General Obesity and Risk of Developing Rheumatoid Arthritis in Women

OBJECTIVE

Being overweight or obese increases rheumatoid arthritis (RA) risk among women, particularly among those diagnosed at a younger age. Abdominal obesity may contribute to systemic inflammation more than general obesity; thus, we investigated whether abdominal obesity, compared to general obesity, predicted RA risk in 2 prospective cohorts: the Nurses' Health Study (NHS) and NHS II.

METHODS

We followed 50,682 women (1986-2014) in NHS and 47,597 women (1993-2015) in NHS II, without RA at baseline. Waist circumference (WC), BMI, health outcomes, and covariate data were collected through biennial questionnaires. Incident RA cases and serologic status were identified by chart review. We examined the associations of WC and BMI with RA risk using time-varying Cox proportional hazards models. We repeated analyses restricted to age ≤ 55 years.

RESULTS

During 28 years of follow-up, we identified 844 incident RA cases (527 NHS, 317 NHS II). Women with WC > 88 cm (35 in) had increased RA risk (HR 1.22, 95% CI 1.06-1.41). A similar association was observed for seropositive RA, which was stronger among young and middle-aged women. Further adjustment for BMI attenuated the association to null. In contrast, BMI was associated with RA (HRBMI ≥ 30 vs < 25 1.33, 95% CI 1.05-1.68) and seropositive RA, even after adjusting for WC, and, as in WC analyses, this association was stronger among young and middle-aged women.

CONCLUSION

Abdominal obesity was associated with increased RA risk, particularly for seropositive RA, among young and middle-aged women; however, it did not independently contribute to RA risk beyond general obesity.

Obesity-Related Traits and the Development of Rheumatoid Arthritis: Evidence From Genetic Data

Objective

To investigate the association between obesity‐related traits and risk of rheumatoid arthritis (RA).

Methods

We conducted genetic correlation analysis and a 2‐sample Mendelian randomization (MR) study, using genome‐wide genetic data based on >850,000 individuals of European ancestry. Summary statistics were collected from the largest genome‐wide association study conducted to date for body mass index (BMI; n = 806,810), waist‐to‐hip ratio (WHR; n = 697,734), WHR adjusted for BMI (WHRadjBMI; n = 694,649), and RA (n_case = 14,361, n_control = 43,923). We conducted cross‐trait linkage disequilibrium score regression and ρ‐HESS analyses to quantify genetic correlation between pairs of traits (causal overlap). For each obesity‐related exposure, we utilized independent, genome‐wide significant single‐nucleotide polymorphisms (P < 5 × 10⁻⁹) as instruments to perform MR analysis (causal relationship). We interrogated the causal relationship both in the general population and in a sex‐specific manner and calculated odds ratios (ORs) and 95% confidence intervals (95% CIs). Sensitivity analyses were performed to validate MR model assumptions.

Results

Despite a negligible overall genetic correlation between the 3 obesity‐related traits and RA, we found significant local genetic correlations at several regions on chromosome 6 (positions 28–29M, 30–35M, and 50–52M), highlighting a shared genetic basis. We further observed an increased risk of RA per SD increment (4.8 kg/m²) in genetically predicted BMI (OR 1.22 [95% CI 1.09–1.37]). The effect was consistent across sensitivity analyses and comparable between sexes (OR 1.22 [95% CI 1.04–1.44] in male subjects and 1.19 [95% CI 1.04–1.36] in female subjects). However, we did not find evidence supporting a causal role of either WHR (OR 0.98 [95% CI 0.84–1.14]) or WHRadjBMI (OR 0.90 [95% CI 0.79–1.04]) in RA.

Conclusion

Genetically predicted BMI significantly increases RA risk. Future studies are needed to understand the biologic mechanisms underlying this link.

Adiposity and the risk of rheumatoid arthritis: a systematic review and meta-analysis of cohort studies

Several studies have investigated associations between overweight/obesity and risk of developing rheumatoid arthritis, however, the evidence is not entirely consistent, and previous meta-analyses mainly included case–control studies, which can be affected by various biases. We therefore conducted a systematic review and meta-analysis of cohort studies on adiposity and risk of rheumatoid arthritis. Relevant studies were identified by searching PubMed and Embase databases. Random effects models were used to estimate summary relative risks (RRs) and 95% confidence intervals (CIs) for rheumatoid arthritis in relation to different measures of adiposity. Thirteen cohort studies (10 publications) were included. The summary RR per 5 kg/m² increase in body mass index (BMI) was 1.11 (95% CI 1.05–1.18, I² = 50%), but the association was restricted to women (1.15, 95% CI 1.08–1.21, I² = 17%) and not observed in men (0.89, 95% CI 0.73–1.09, I² = 58%). The summary RR per 5 kg/m² increment in BMI at age 18 years was 1.17 (95% CI 1.01–1.36, I² = 26%, n = 3), and per 10 cm increase in waist circumference was 1.13 (95% CI 1.02–1.25, I² = 44%, n = 2). Higher BMI in middle age, BMI at age 18 years, and waist circumference were associated with increased rheumatoid arthritis risk, suggesting adiposity could be targeted for primary prevention.

Bariatric surgery and the incidence of rheumatoid arthritis - a Swedish Obese Subjects study

Objective

The aim of this study was to determine the effect of bariatric surgery on the incidence of RA in participants of the Swedish Obese Subjects (SOS) study.

Methods

The SOS is a longitudinal study aiming to assess the effect of bariatric surgery on mortality and obesity-related diseases. This report includes 2002 subjects with obesity who underwent bariatric surgery and 2034 matched controls; none of them had RA at baseline. Cases of incident RA were identified through the Swedish National Patient Register by searching for International Classification of Diseases codes. Both intention-to-treat analyses and per-protocol analyses are reported. In the per-protocol analysis, participants from the control group who underwent bariatric surgery later on during follow-up were censored at the time of surgery.

Results

During follow-up, 92 study participants developed RA. The median follow-up was 21 years (range 0–29). Bariatric surgery was neither associated with the incidence of RA in the intention-to-treat analysis [hazard ratio (HR) 0.92 (95% CI 0.59, 1.46), P = 0.74], nor in the per-protocol analysis [HR 0.86 (95% CI 0.54, 1.38), P = 0.53]. Weight change at the 2 year follow-up, expressed as the change in BMI compared with baseline, did not associate with the development of RA. Higher serum CRP levels and smoking associated with the future development of RA independent of other factors.

Conclusions

We did not detect any association between bariatric surgery and the incidence of RA in subjects affected by obesity followed up for up to 29 years.

ClinicalTrials.gov

(http://clinicaltrials.gov): NCT01479452.

Dietary Habits and Nutrition in Rheumatoid Arthritis: Can Diet Influence Disease Development and Clinical Manifestations?

Rheumatoid arthritis (RA) is a systemic, autoimmune disease characterized by joint involvement, with progressive cartilage and bone destruction. Genetic and environmental factors determine RA susceptibility. In recent years, an increasing number of studies suggested that diet has a central role in disease risk and progression. Several nutrients, such as polyunsaturated fatty acids, present anti-inflammatory and antioxidant properties, featuring a protective role for RA development, while others such as red meat and salt have a harmful effect. Gut microbiota alteration and body composition modifications are indirect mechanisms of how diet influences RA onset and progression. Possible protective effects of some dietary patterns and supplements, such as the Mediterranean Diet (MD), vitamin D and probiotics, could be a possible future adjunctive therapy to standard RA treatment. Therefore, a healthy lifestyle and nutrition have to be encouraged in patients with RA.

Improving accuracy of self-reported diagnoses of rheumatoid arthritis in the French prospective E3N-EPIC cohort: a validation study

OBJECTIVES

The French E3N-EPIC (Etude Epidémiologique auprès des femmes de la Mutuelle générale de l'Education Nationale-European Prospective Investigation into Cancer and Nutrition) cohort enrolled 98 995 women aged 40 to 65 years at inclusion since 1990 to study the main risk factors for cancer and severe chronic conditions in women. They were prospectively followed with biennially self-administered questionnaires collecting self-reported medical, environmental and lifestyle data. Our objective was to assess the accuracy of self-reported diagnoses of rheumatoid arthritis (RA) and to devise algorithms to improve the ascertainment of RA cases in our cohort.

DESIGN

A validation study.

PARTICIPANTS

Women who self-reported an inflammatory rheumatic disease (IRD) were asked to provide access to their medical record, and to answer an IRD questionnaire. Medical records were independently reviewed.

PRIMARY AND SECONDARY OUTCOME MEASURES

Positive predictive values (PPV) of self-reported RA alone, then coupled with the IRD questionnaire, and with a medication reimbursement database were assessed. These algorithms were then applied to the whole cohort to ascertain RA cases.

RESULTS

Of the 98 995 participants, 2692 self-reported RA. Medical records were available for a sample of 399 participants, including 305 who self-reported RA. Self-reported RA was accurate only for 42% participants. Combining self-reported diagnoses to answers to a specific IRD questionnaire or to the medication reimbursement database improved the PPV (75.6% and 90.1%, respectively). Using the devised algorithms, we could identify 964 RA cases in our cohort.

CONCLUSION

Accuracy of self-reported RA is poor but adding answers to a specific questionnaire or data from a medication reimbursement database performed satisfactorily to identify RA cases in our cohort. It will subsequently allow investigating many potential risk factors of RA in women.

Long-Term Physical Activity and Subsequent Risk for Rheumatoid Arthritis Among Women: A Prospective Cohort Study

OBJECTIVE

To evaluate the effects of long-term physical activity on subsequent risk of rheumatoid arthritis (RA) in a prospective cohort study.

METHODS

This study investigated physical activity and RA risk among women from the Nurses' Health Study II (1989-2015). Physical activity exposures and covariates were prospectively obtained using biennial questionnaires. Two rheumatologists independently reviewed the medical records of women who self-reported a new diagnosis of RA on biennial questionnaires and who screened positive for RA based on a supplemental survey. All incident RA cases met the 1987 American College of Rheumatology (ACR) or 2010 ACR/European League Against Rheumatism (EULAR) classification criteria for RA. The primary analysis investigated the long-term cumulative average number of hours spent in recreational physical activity 2-8 years prior to the RA diagnosis, a time span chosen to reduce the potential for reverse causation bias, since early RA affects physical activity prior to diagnosis. Estimated Cox regression hazard ratios (HRs) with 95% confidence intervals (95% CIs) were used to assess the risk of RA serologic phenotypes (all, seropositive, or seronegative) in relation to physical activity categories. The analyses were adjusted for body mass index (BMI) at age 18 years and time-varying potential confounders, and the mediating effect of updated BMI on the interaction between physical activity and RA risk was quantified.

RESULTS

Among the 113,366 women analyzed, 506 incident RA cases (67.0% with seropositive RA) were identified during 2,428,573 person-years of follow-up. After adjustment for confounders, including smoking, dietary quality, and BMI at age 18 years, increasing cumulative average total hours of recreational physical activity was associated with a reduced risk of RA, as follows: HR 1.00 for <1 hour/week (reference), HR 1.00 (95% CI 0.78-1.29) for 1 to <2 hours/week, HR 0.92 (95% CI 0.72-1.17) for 2 to <4 hours/week, HR 0.84 (95% CI 0.63-1.12) for 4 to <7 hours/week, and HR 0.67 (95% CI 0.47-0.98) for ≥7 hours/week (P for trend = 0.02). The proportion of the effect between physical activity and RA mediated by updated BMI was 14.0% (P = 0.002) for all RA and 20.0% (P = 0.001) for seropositive RA.

CONCLUSION

Higher levels of physical activity were associated with reduced RA risk. These results add to the literature implicating metabolic factors in the pathogenesis of RA.

Potential of Lifestyle Changes for Reducing the Risk of Developing Rheumatoid Arthritis: Is an Ounce of Prevention Worth a Pound of Cure?

PURPOSE

Lifestyle may be important in the development of rheumatoid arthritis (RA). Therefore, changing behaviors may delay or even prevent RA onset. This article reviews the evidence basis for the associations of lifestyle factors with RA risk and considers future directions for possible interventions to reduce RA risk.

METHODS

The literature was reviewed for cross-sectional studies, case-control studies, cohort studies, and clinical trials investigating potentially modifiable lifestyle factors and RA risk or surrogate outcomes on the path toward development such as RA-related autoimmunity or inflammatory arthritis. The evidence related to cigarette smoking, excess weight, dietary intake, physical activity, and dental health for RA risk were summarized.

FINDINGS

Cigarette smoking has the strongest evidence base as a modifiable lifestyle behavior for increased seropositive RA risk. Smoking may increase seropositive RA risk through gene-environment interactions, increasing inflammation and citrullination locally in pulmonary/oral mucosa or systemically, thereby inducing RA-related autoimmunity. Prolonged smoking cessation may reduce seropositive RA risk. Evidence suggests that excess weight can increase RA risk, although this effect may differ according to sex, serologic status, and age at RA onset. TDietary intake may also affect RA risk: overall healthier patterns, high fish/omega-3 polyunsaturated fatty acid consumption, and moderate alcohol intake may reduce RA risk, whereas caffeine and sugar-sweetened soda consumption might increase RA risk. The impact of physical activity is less clear, but high levels may reduce RA risk. Periodontal disease might induce citrullination and RA-related autoimmunity, but the effect of dental hygiene behaviors on RA risk is unclear. Although the effect size estimates for these lifestyle factors on RA risk are generally modest, there may be relatively large public health benefits for targeted interventions given the high prevalence of these unhealthy behaviors. With the exception of smoking cessation, the impact of behavior change of these lifestyle factors on subsequent RA risk has not been established. Nearly all of the evidence for lifestyle factors and RA risk were derived from observational studies.

IMPLICATIONS

There are many potentially modifiable lifestyle factors that may affect RA risk. Improving health behaviors could have large public health benefits for RA risk given the high prevalence of many of the RA risk-related lifestyle factors. However, future research is needed to establish the effects of lifestyle changes on RA risk or surrogate outcomes such as RA-related autoimmunity or inflammatory arthritis.

Physical Fitness and Body Composition in Women with Systemic Lupus Erythematosus

Background and objectives: Higher physical fitness is associated with a more favorable weight and body composition in the general population, although this association has not been studied in patients with systemic lupus erythematosus (SLE). The aim of the present study was to examine the association of different components of physical fitness with body composition in women with SLE with mild disease activity. Materials and Methods: This cross-sectional study included 77 women with SLE (43.2 ± 13.8 years old) and clinical stability during the previous 6 months. Body composition (including body mass index (BMI), fat mass index (FMI), waist circumference, waist-to-height ratio and waist-to-hip ratio) was assessed using a stadiometer, an anthropometric tape, and a bioimpedance device. Physical fitness included cardiorespiratory fitness (Siconolfi step test and 6 min walk test), muscular strength (handgrip strength test as upper body measure and 30 s chair stand as lower body measure), and flexibility (back-scratch test). Participants with a fitness level equal or above the median of the study sample were categorized as "fit" and those below the median were categorized as "unfit". Linear regression assessed the association of physical fitness with body composition parameters. Results: Cardiorespiratory fitness and upper body muscular strength were negatively associated with BMI, FMI, waist circumference, and waist-to-height ratio (all, p < 0.05). Lower body muscular strength and flexibility were negatively related to FMI, waist circumference, waist-to-height ratio, and waist-to-hip ratio (all, p < 0.05). These relationships were still significant after controlling for age, disease duration, accrual damage, and SLE activity. Overall, fit patients presented significantly lower values in all body composition parameters compared to unfit patients (all, p < 0.05). Conclusions: The main findings of the present study suggest that physical fitness is inversely associated with body composition in women with SLE. Given the cross-sectional nature of this study, future clinical trials should study the causal pathways underlying these relationships.