The association between dietary inflammation index and the risk of rheumatoid arthritis in Americans

Prevalence of anemia in patients with rheumatoid arthritis and its association with dietary inflammatory index: A population-based study from NHANES 1999 to 2018

Anemia is common in patients with rheumatoid arthritis (RA), and it is unknown whether the dietary inflammatory index (DII) is linked to anemia. This study aimed to clarify the prevalence of anemia in RA patients and its association with the DII. The data utilized in this study were collected from the National Health and Nutrition Examination Survey database from 1999 to 2018. The prevalence of anemia in RA patients was estimated by ethnicity, sex, and age. Weighted multivariate logistic regression was utilized to explore the correlation between anemia risk and DII. The most crucial dietary factors related to the risk of anemia in RA patients were screened by stepwise regression. A nomogram model was established according to key dietary factors. A total of 10.25% (confidence interval, 8.58-11.92%) of RA patients will develop anemia, with the lowest prevalence around the age of 60. In addition, higher DII levels were discovered in anemic patients than in nonanemic patients. In multivariate regression models, an important positive association was revealed between anemia and growing quartiles of DII (Q4 vs Q1: odds ratio = 1.98; confidence interval, 1.25-3.15). In the subgroup analysis, the adjusted relation of DII with anemia in females, Mexicans, smokers, nondrinkers, and age groups ≥ 60 years was statistically significant. The same association was observed in the sensitivity analysis. A nomogram model based on stepwise regression screening of key dietary factors showed good discriminatory power to identify anemic risk in RA patients (area under the curve: 0.707). In patients with RA, high DII levels were associated with the risk of anemia. More attention should be given to controlling dietary inflammation to better prevent and treat anemia.

Association between dietary inflammation index and albuminuria: results from the National Health and Nutrition Examination Survey

Background

The Dietary Inflammation Index (DII) is a tool for evaluating the potential for dietary inflammation, and inflammation is a major cause of exacerbation in chronic kidney disease. Our study aimed to investigate the relationship between DII and albuminuria.

Methods

Data were obtained from the 2005-2018 National Health and Nutrition Examination Survey (NHANES) after excluding pregnant, minors, and missing data of urinary albumin-creatinine ratio (ACR), estimated glomerular filtration rate (eGFR), and DII were enrolled in our study. Albuminuria was defined as ACR > 30 mg/g. DII was calculated and divided into tertiles. After fully adjusted, multivariate logistic regression analysis and subgroup analysis were performed to investigate the association between DII and albuminuria.

Results

A total of 22,607 participants including 2,803 (12.40%) with and 19,804 (87.60%) without albuminuria were enrolled in our study. The albuminuria increased with the increasing DII tertiles (Tertile 1: 10.81%; Tertile 2: 12.41%; Tertile 3:13.97%, P < 0.001). After fully adjusting for covariates, multivariate logistic regression showed that the higher the DII, the greater the odds of albuminuria (OR = 1.19; 95% CI, 1.00-1.41, P < 0.001). Subgroup analysis and interaction test of participants found that the positive correlation between DII and albuminuria was not significantly related to gender, age, BMI, hypertension, diabetes, and eGFR (P for interaction >0.05).

Conclusion

Elevated DII is associated with high odds of albuminuria. Further large-scale prospective studies are still needed to analyze the role of DII in albuminuria.

Associations of dietary inflammatory index with low estimated glomerular filtration rate, albuminuria and chronic kidney disease in U.S adults: Results from the NHANES 2011-2018

BACKGROUND AND AIMS

Chronic Kidney Disease (CKD) is characterized by a high inflammation status with ever-increasing prevalence, and defined as low estimated glomerular filtration rate (eGFR) or albuminuria. Both low eGFR and albuminuria can have independent effects on the body. The dietary inflammatory index (DII) is a validated tool used to assess the inflammatory potential of the diet. We aim to explore not only the association between DII and CKD, but also the associations of DII with low eGFR and albuminuria, respectively. In addition, their associations in different subgroups remain to be explored.

METHODS AND RESULTS

18,070 participants from the 2011-2018 NHANES with complete data of dietary intake and laboratory data were involved in our study. The data of 24-hour dietary recall interview was used to calculate DII, CKD could be reflected by laboratory data of creatinine and albumin. Then weighted multivariate logistic regression models and subgroup analyses were performed. The prevalence of low eGFR, albuminuria and CKD were 6.8%, 9.8% and 14.5%, respectively. A positive association between DII and low eGFR was observed (OR=1.12, 95%CI: 1.05-1.21), Q2, Q3 and Q4 are positively associated with a significant 39%, 65% and 71% increased risk of low eGFR compared with Q1 (P for trend<0.05). DII was also associated with CKD (OR=1.06, 95%CI: 1.01-1.11).

CONCLUSION

Significant positive associations of DII with CKD and low eGFR were observed. But we didn't find such association between DII and albuminuria.

Association between dietary inflammatory index and chronic kidney disease in middle-aged and elderly populations

Background

A link between food-induced inflammation and common chronic diseases has been identified in studies. However, there was uncertainty about the influence of dietary inflammatory potential on the risk of chronic kidney disease (CKD) among middle-aged and older groups. Our research aimed to examine the connection between dietary inflammatory index (DII) to CKD in people aged 40 years and older.

Methods

This study comprised ten cycles of the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018. Linear associations of DII with CKD, low-eGFR, and albuminuria were examined using multiple logistic regression, whereas non-linear associations were assessed by smoothed curve fitting. Besides, we conducted subgroup analyses and interaction tests.

Results

Of the 23,175 middle-aged and older individuals, a total of 5,847 suffered from CKD, making up 25.23% of all participants. After adjustment for all covariates, we found that increased DII scores were positive with an increased hazard of CKD (OR = 1.08, 95% CI: 1.05, 1.10, p < 0.0001), and the same was shown between DII and low-eGFR (OR = 1.16, 95% CI: 1.13, 1.19, p < 0.0001). After further converting DII into categorical variables, the above relationship still existed. These relations were consistent in different ages, genders, BMI, whether smoking, whether suffering from hypertension, and whether suffering from diabetes, with no significant stratification differences (all P for interaction >0.05). Surprisingly, we did not find a statistically significant correlation of DII to albuminuria after complete adjustment for covariates (OR = 1.02, 95% CI: 1.00, 1.05, p = 0.0742). Even when DII was considered as a categorical variable, this relation was still not statistically significant. Furthermore, we found an association in the shape of a U between DII and low-eGFR in the fully adjusted model, with a turning point at a DII of 1.6.

Conclusion

Our findings indicated that middle-aged and older persons with greater levels of DII had a significantly higher risk of CKD.

Association between dietary inflammatory index and anemia in US adults

Background and aims

Anemia is a widespread global health concern, and recent research has unveiled a link between anemia and inflammation. The Dietary Inflammation Index (DII) is a novel tool used to assess the overall inflammatory potential of an individual's diet. However, until now, there have been no studies demonstrating a connection between DII and anemia. This study aimed to explore the relationship between DII and the risk of anemia among Americans, as well as to examine the influence of other risk factors on this association.

Methods

Data from 32,244 patients were collected from the National Health and Nutrition Examination Survey (NHANES) database spanning from 1999 to 2018. Using multivariable logistic regression, we examined the correlation between DII and anemia. Subgroup analyses and smoothed curve analyses were conducted to further investigate the association between DII and anemia.

Results

The analysis revealed a significant positive association between higher DII scores and increased anemia risk in the American population (Odds Ratio [OR] = 1.06, 95% Confidence Interval [CI] = 1.03 to 1.09, p < 0.0001). This association remained consistent in subgroup analyses, encompassing various age groups, distinct Body Mass Index (BMI) categories, varying diabetes mellitus statuses, histories of hypertension, females, individuals with a RIP <3.5, and Non-Hispanic Black individuals. Notably, the association was particularly significant among non-smokers. Smoothed curve fitting analysis demonstrated a linear relationship between DII and the prevalence of anemia.

Conclusion

Our findings underscore a positive correlation between the inflammatory potential of one's diet and the risk of anemia, especially when coupled with other risk factors. Consequently, reducing the consumption of pro-inflammatory foods may serve as one of the effective measures against the development of anemia. Given the variations in gender, age, BMI, and chronic diseases observed in our study, tailored policies could better cater to the specific needs of diverse populations.

Association between combined exposure to dioxins and arthritis among US adults: a cross-sectional study

Dioxins and dioxin-like compounds (DLCs) are common pollutants hazardous to human health. We applied 12 dioxins and DLCs data of 1851 participants (including 484 arthritis patients) from National Health Examination Survey (NHANES) 2001-2004 and quadrupled them into rank variables. Multivariate logistic regression, weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) models were used to explore the relationship between individual or mixed exposure to the pollutants and arthritis after adjusting for multiple covariates. In multivariable logistic regression with an individual dioxin or DLC, almost every chemical was significantly positively associated with arthritis, except PCB66 (polychlorinated biphenyl 66) and 1,2,3,4,6,7,8-heptachlorodibenzofuran (hpcdf). The WQS model indicated that the combined exposure to the 12 dioxins and DLCs was positively linked to arthritis (OR: 1.884, 95% CI: 1.514-2.346), with PCB156 (weighted 0.281) making the greatest contribution. A positive trend between combined exposure and arthritis was observed in the BKMR model, with a posterior inclusion probability (PIP) of 0.987 for PCB156, which was also higher than the other contaminants.

Dietary Inflammatory Index and Clinical Outcome Measures in Adults With Moderate-to-Severe Asthma

BACKGROUND

Diet is increasingly recognized as a modifiable factor in lung health, predominantly due to the immunomodulatory effects of nutrients. The Dietary Inflammatory Index (DII) is a score developed to express the inflammatory potential of a diet.

OBJECTIVE

We aimed to assess the association of the DII and food groups, with clinical, functional, and inflammatory asthma outcomes in adults with asthma.

METHODS

Patients with moderate-to-severe asthma were included in this cross-sectional study between June 2019 and October 2021, and completed a 3-day food diary, to calculate the DII and intake of food groups (ie, fruits, whole grains, processed meats, and sugar-sweetened beverages). Functional outcomes included pulmonary function tests and the 6-minute walking distance, whereas clinical outcomes were assessed using questionnaires on asthma control, quality of life, and health care utilization. Inflammatory markers were exhaled nitric oxide and blood leukocytes, eosinophils, and IL-6. Multivariable regression analyses were used to examine the association of DII and food groups with asthma outcomes.

RESULTS

A total of 109 patients participated (35% male, mean ± standard deviation age 51.8 ± 14.2 years, body mass index 27.4 ± 5.3 kg/m2). Overall, 62% had a DII score >0, indicating a proinflammatory diet, which was not related to asthma severity. A more proinflammatory diet was consistently associated with lower forced vital capacity (%pred), but inconsistent results were observed with respect to airway obstruction. Neither the DII nor food groups were associated with clinical outcomes. Except for higher levels of exhaled nitric oxide in relation to an anti-inflammatory diet, we found no associations between inflammatory markers and the DII.

CONCLUSION

Results from this cross-sectional study among patients with moderate-to-severe asthma do not support the hypothesis that a proinflammatory diet is associated with worse asthma outcomes, although limitations in study design and dietary intake estimation should be considered. Future well-designed experimental studies are needed to assess whether targeting the inflammatory potential of diet could lead to better outcomes in adults with asthma.

Correlation between dietary inflammation and mortality among hyperlipidemics

BACKGROUND AND OBJECTIVE

Although the the Dietary Inflammatory Index (DII) serves to be one of the reliable indicator for hyperlipidaemia, there is still uncertainty about its relationship to prognosis in the hyperlipidaemic population. In current study, the DII levels were analyzed in relation to the mortality risk among among the hyperlipidaemic individuals with the aim of determining any prospective correlation.

METHODS

14,460 subjects with hyperlipidaemia from the 10-year (2001-2010) National Health and Nutrition Examination Survey (NHANES) were chosen for this study. The endpoint event for follow-up was all-cause mortality, and subjects were tracked for up to December 31, 2019, or death, whichever occurred first. The tertiles of the DII levels were utilized for categorizing the study population into three groups. Survival curves, Cox proportional hazards regression models, restricted cubic spline (RCS), subgroup and interaction analyses, and sensitivity analyses were employed sequentially for the purpose of evaluating the association of the DII with mortality.

RESULTS

3170 (21.92%) all-cause deaths were recorded during an average 148-month follow-up period. Kaplan-Meier survival curves indicated that the survival rate of participants divided into the low DII group was substantially improved compared to that of those in the higher DII group (log-rank P < 0.001). After controlling for confounders, higher levels of DII were observed to be meaningfully linked to an elevated risk of death, no matter whether DII was specified for the continuous (hazard ratio (HR): 1.06; 95% confidence interval (CI): 1.04-1.08) or the categorical variable (HR: 1.22; 95% CI: 1.11-1.33). The DII and mortality displayed a linear association, according to the RCS. Stratified and sensitivity analyses reinforced the proof that these findings were reliable.

CONCLUSION

Among patients with hyperlipidaemia, the risk of death was positively and linearly linked with DII levels.

Association of energy-adjusted dietary inflammatory index and frailty in older adults with nonalcoholic fatty liver disease

BACKGROUND

Energy-adjusted dietary inflammatory index (E-DII) can represent daily inflammatory dietary components and chronic inflammatory response is an important pathogenesis of aging, nonalcoholic fatty liver disease (NAFLD) and frailty. Therefore, the purpose of this study is to explore the association of E-DII and frailty in older adults with NAFLD.

METHODS

This cross-sectional study utilized data from the National Health and Nutrition Examination Survey (2005-2016) to investigate the association between E-DII and frailty. The NAFLD status was determined using the US Fatty Liver Index (FLI) value ≥30. The relationship between E-DII and frailty was examined through multivariate weighted logistic regression analysis and smooth curve fitting. Subgroup analyses were conducted, considering various demographic and clinical variables.

RESULTS

Our final analysis included 1586 individuals, with an average age of 69.42 years, and 53.15 % of them were males. The overall prevalence of frailty in the study population was 39.42 %. Smooth curve fitting analysis demonstrated a nearly linear relationship between E-DII and H. pylori. Utilizing multivariate weighted logistic regression analysis, we found that the odds ratio (OR) of E-DII for frailty was 1.08 (95%CI, 1.03-1.15). Subgroup analysis further confirmed that E-DII independently increased the risk of frailty.

CONCLUSION

Higher E-DII levels were found to be associated with an increased risk of frailty in older adults with NAFLD. However, further studies are required to fully elucidate the precise mechanisms underlying the relationship between E-DII and frailty.

The Mediterranean diet, and not dietary inflammatory index, is associated with rheumatoid arthritis disease activity, the impact of disease and functional disability

PURPOSE

To assess the relationship between adherence to the Mediterranean Diet (MD) /individual Dietary Inflammatory Index (DII) and disease activity, disease impact, and functional status in Rheumatoid Arthritis (RA) patients.

METHODS

RA patients followed at a hospital in Lisbon, Portugal, were recruited. DII was calculated using dietary intake data collected with a food frequency questionnaire (FFQ). Adherence to the MD was obtained using the 14-item Mediterranean Diet assessment tool. Disease Activity Score of 28 Joints (DAS28) and the DAS28 calculated with C-Reactive Protein (DAS28-CRP) were used to assess disease activity. Impact of disease and functional status were evaluated using the Rheumatoid Arthritis Impact of Disease (RAID) questionnaire and the Health Assessment Questionnaire (HAQ), respectively.

RESULTS

120 patients (73.3% female, 61.8 ± 10.1 years of age) were included. Patients with higher adherence to the MD had significantly lower DAS28-CRP (median 3.27(2.37) vs 2.77(1.49), p = 0.030), RAID (median 5.65(2.38) vs 3.51(4.51), p = 0.032) and HAQ (median 1.00(0.56) vs 0.56(1.03), p = 0.013) scores. Higher adherence to the MD reduced the odds of having a higher DAS28 by 70% (OR = 0.303, 95%CI = (0.261, 0.347), p = 0.003). Lower adherence to MD was associated with higher DAS28-CRP (β = - 0.164, p = 0.001), higher RAID (β = - 0.311, p < 0.0001), and higher HAQ scores (β = - 0.089, p = 0.001), irrespective of age, gender, BMI and pharmacological therapy. Mean DII of our cohort was not significantly different from the Portuguese population (0.00 ± 0.17 vs - 0.10 ± 1.46, p = 0.578). No associations between macronutrient intake or DII and RA outcomes were found.

CONCLUSIONS

Higher adherence to the MD was associated with lower disease activity, lower impact of disease, and lower functional disability in RA patients.

Associations between exposure to phthalates and rheumatoid arthritis risk among adults in NHANES, 2007-2016

BACKGROUND

The etiology of rheumatoid arthritis (RA) is multifactorial, encompassing genetics and environment. Despite the widespread use of phthalates as chemical additives, their potential impact on RA has received limited investigation. This study aimed to evaluate the potential associations between exposure to phthalates and rheumatoid arthritis risk among adults.

METHODS

Participants ≥20 years were analyzed from the National Health and Nutrition Examination Survey (NHANES) 2007-2016. Multivariable logistic regression was used to examine the association between exposure to phthalates and RA in two models. Additionally, subgroup analyses stratified by gender and age were also performed. The nonlinear relationship between RA and phthalates was characterized by smooth curve fittings and generalized additive models.

RESULTS

Ultimately, 9322 participants (RA: 601, without RA: 8632) were analyzed. The prevalence of RA increased with higher quantiles of MECPP (Q4, OR: 1.43, 95% CI: 1.07-1.91), MBP (Q2, OR: 1.30, 95% CI: 1.01-1.67), MEHHP (Q3, OR: 1.39, 95% CI: 1.07-1.81; Q4, OR: 1.35, 95% CI: 1.02-1.87) and MEOP (Q2, OR:1.35, 95% CI: 1.03-1.76) compared to the lowest quartile. A nonlinear relationship positive association was also observed between MECPP (P for non-linearity = 0.0074)) and MEHHP (P for non-linearity = 0.0046)) levels and RA. Subgroup analysis showed the association between phthalate levels and RA was mainly present in males or participants aged more than 60 years.

CONCLUSIONS

Our results demonstrated that exposure to phthalates is associated with an increased prevalence of RA among adults. Notably, such associations appear to be more pronounced in males and older people.

The association between triglyceride glucose index and arthritis: a population-based study

OBJECTIVES

Insulin resistance is a well-established contributor to inflammation; however, the specific association between the triglyceride glucose (TyG) index, a biomarker reflecting insulin resistance, and arthritis remains unexplored. As a result, the main aim of this study was to examine the correlation between the TyG index and arthritis.

METHODS

This observational study used data from the National Health and Nutrition Examination Survey (NHANES), which was conducted between 2007 and 2018. To investigate the relationship between the TyG index and arthritis, various statistical analyses were employed, including weighted multivariable logistic regression analysis, subgroup analysis, curve fit analysis, and threshold effect analysis.

RESULTS

In total, 14,817 patients were enrolled in the trial, with 4,191 individuals (28.29%) diagnosed with arthritis. An increased risk of arthritis was found to be significantly correlated with higher TyG index values (odds ratio OR = 1.15, 95% confidence interval CI: 1.07-1.23), according to the results of multivariable logistic regression analysis after full adjustment. Subgroup analysis and interaction tests further indicated that the TyG index exhibited an additive effect when combined with other established risk factors, including age (OR = 1.29; 95% CI: 1.17-1.41), body mass index (BMI) (OR = 1.43; 95% CI: 1.24-1.69), and diabetes (OR = 1.20; 95% CI: 1.11-1.31). Additionally, curve fit analysis and threshold effect analysis demonstrated a nonlinear relationship with a breakpoint identified at 8.08 µmol/L.

CONCLUSION

The TyG index was positively correlated with arthritis in adults under 60 years of age in the United States who had normal weight and no diabetes. Further large-scale prospective studies are warranted for a comprehensive analysis of the role of the TyG index in arthritis.

Metabolomics Analysis of DRG and Serum in the CCI Model of Mice

Neuropathic pain (NP) is a chronic and intractable disease that is widely present in the general population. It causes painful behavior and even mood changes such as anxiety and depression by altering the metabolism of substances. However, there have been limited metabolomics studies conducted in relation to neuropathic pain. Therefore, in this study, the effects of NP on metabolites in serum and the dorsal root ganglion (DRG) were investigated using a non-targeted metabolomics approach detected by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) to uncover differential metabolites and affected metabolic pathways associated with NP. Sixty mice were divided into the following two groups: a chronic constriction injury (CCI) of the sciatic nerve group and a sham group (n = 30, each). After 7 days of CCI modeling, the metabolite profiles of serum and the DRG were analyzed using GC/LC-MS for both the CCI and sham groups of mice. Multivariate analysis revealed differential metabolites and altered metabolic pathways between the CCI and sham groups. In the CCI group, our findings provided insights into the complex phospholipid, amino acid and acylcarnitine metabolic perturbations of DRG metabolism. In addition, phospholipid metabolic disorders and impaired glucose metabolism were observed in the serum. Moreover, the metabolic differences in the DRG and serum were correlated with each other. The results from this untargeted metabolomics study provide a perspective on the metabolic impact of NP on serum and the DRG.

Association of Dietary Inflammation Index and Helicobacter pylori Immunoglobulin G Seropositivity in US Adults: A Population-Based Study

Background

Dietary patterns play important role in Helicobacter pylori (H. pylori) infection. We aimed to investigate the potential relationship between Dietary Inflammation Index (DII) and H. pylori infection in US adults.

Methods

This cross-sectional study was based on National Health and Nutrition Examination Survey (1999-2000). Individuals aged ≥20 years who provided a 24 hr dietary intake history and underwent H. pylori testing were included in the analysis. Multivariate weighted logistic regression analysis, smooth curve fitting, and subgroup analysis were used to investigate the relationship between DII and H. pylori infection. Subgroup analyses were based on demographic and clinical variables.

Results

There were 4,000 individuals enrolled in our final analysis. The overall mean age was 45.92 years and 46.77% were males. The overall prevalence of H. pylori infection in the study population was 45.9%. The smooth curve fitting analysis indicated a near-linear relationship between DII and H. pylori. In multivariate weighted logistic regression analysis, the odds ratio (OR) of DII is 1.17 (95% confidence interval (CI), 1.09-1.27) for H. pylori infection. In subgroup analysis, DII still increased the risk of H. pylori infection independently.

Conclusions

The increased DII levels were associated with an increased risk of H. pylori infection among US adults. Further studies are needed to elucidate the exact mechanisms of DII and H. pylori infection.

Dietary inflammatory potential and biological aging among US adults: a population-based study

OBJECTIVES

The rate of biological aging is influenced by various factors such as genetics, environment, and diet. The dietary inflammatory index (DII) is strongly associated with various chronic diseases. The aim of this study was to investigate the association between DII and biological aging in US adults using quantitative indicators.

METHODS

Based on data from the National Health and Nutrition Examination Survey (NHANES) 1999-2018, weighted multiple linear regression models, generalized weighted models, and smoothed fitted curves were used to investigate the linear and nonlinear relationships of DII with four biological markers of aging (biological age, phenotypic age, telomere length, and serum klotho concentration).

RESULTS

A total of 35,575 adult participants with complete data were included in the study. After adjusting for all confounders, significant positive correlations were found between DII with biological age [0.070 (0.045, 0.095)] and phenotypic age [0.421 (0.371, 0.471)], with an increase of 0.07 and 0.42 years in biological age and phenotypic age, respectively, for each increase in DII score. The negative correlations between DII with telomere length [ - 0.005 ( - 0.008, - 0.002)] and klotho [ - 3.874 ( - 7.409, - 0.338)] were significant only in partially adjusted models and differed across subgroups.

CONCLUSIONS

In the current study, higher DII scores (greater pro-inflammatory dietary potential) were associated with biological aging. These findings may contribute to the development of aging prevention strategies through dietary interventions.

Causal association between rheumatoid arthritis and celiac disease: A bidirectional two-sample mendelian randomization study

Objectives: Rheumatoid Arthritis (RA) has been associated with Celiac Disease (CD) in previous observational epidemiological studies. However, evidence for this association is limited and inconsistent, and it remains uncertain whether the association is causal or due to confounding or reverse causality. This study aimed to assess the bidirectional causal relationship between RA and CD. Methods: In this two-sample Mendelian randomization (MR) study, instrumental variables (IVs) for RA were derived from a genome-wide association studies (GWAS) meta-analysis including 58,284 subjects. Summary statistics for CD originated from a GWAS meta-analysis with 15,283 subjects. The inverse-variance weighted (IVW) method was used as the primary analysis. Four complementary methods were applied, including the weighted-median, weighted mode, MR pleiotropy residual sum and outlier (MR-PRESSO) test and MR-Egger regression, to strengthen the effect estimates. Results: Positive causal effects of genetically increased RA risk on CD were derived [IVW odds ratio (OR): 1.46, 95% confidence interval (CI): 1.19-1.79, p = 3.21E-04]. The results of reverse MR analysis demonstrated no significant causal effect of CD on RA (IVW OR: 1.05, 95% CI: 0.91-1.21, p = 0.499). According to the sensitivity analysis, horizontal pleiotropy was unlikely to distort the causal estimates. Conclusion: This study reveals a causality of RA on CD but not CD on RA among patients of European descent. This outcome suggests that the features and indicators of CD should regularly be assessed for RA patients.