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ObjectiveAge at rheumatoid arthritis (RA) onset varies by geographical latitude. We have investigated to what extent differences in patient-specific factors and country-level socioeconomic indicators explain this variability.MethodsPatients with RA from the worldwide METEOR registry were included. Bayesian multilevel structural equation models were used to study the relationship between the absolute value of (hospital) geographical latitude and age at diagnosis (as a proxy for age at RA onset). We examined to what extent this effect is mediated by individual patient characteristics and by country-specific socioeconomic indicators and disentangled whether the observed effects occurred at the patient, hospital, or country levels.ResultsWe included 37 981 patients from 93 hospitals in 17 geographically widespread countries. Mean age at diagnosis per country ranged from 39 (Iran) to 55 (Netherlands) years. Per degree increase in country latitude (between 9.9° and 55.8°), mean age at diagnosis increased by 0.23 years (95% credibility interval: 0.095 to 0.38) (reflecting >10 years difference in age at RA onset). For hospitals within a country, this latitude effect was negligible. Inclusion of patient-specific factors (eg, gender, anticitrullinated protein antibodies status) in the model augmented the main effect from 0.23 to 0.36 years. Inclusion of country-level socioeconomic indicators (eg, gross domestic product per capita) in the model almost effaced the main effect (from 0.23 to 0.051 (−0.37 to 0.38)).ConclusionsPatients living closer to the equator get RA at a younger age. This latitude gradient was not explained by individual patient characteristics, but rather by countries’ socioeconomic status, providing a direct link between countries’ level of welfare and the clinical onset of RA.

Microbial lipopolysaccharides (LPS) have been implicated in the pathogenesis of rheumatoid arthritis (RA), possibly driving a systemic inflammatory response that may trigger the development and/or exacerbation of the disease. To explore the existence of this mechanism in African RA patients, we have measured systemic levels of LPS and its surrogate, LPS-binding protein (LBP), as well as those of intestinal fatty acid-binding protein (I-FABP), pulmonary surfactant protein D (SP-D), and cotinine in serum to identify possible origins of LPS, as well as associations of these biomarkers with rheumatoid factor (RF) and anticitrullinated peptide (aCCP) autoantibodies and the DAS 28-3 clinical disease severity score. A cohort of 40 disease-modifying antirheumatic drug-naïve, black South African RA patients rated by compound disease scores and 20 healthy subjects and 10 patients with chronic obstructive pulmonary disease (COPD) as controls were included in this study. Levels of the various biomarkers and autoantibodies were measured using a combination of ELISA and immunofluorimetric and immunoturbidometric procedures. LPS levels were lowest in the RA group compared to the healthy controls (p=0.026) and COPD patients (p=0.017), while LBP levels were also significantly lower in RA compared to the healthy individuals (p=0.036). Levels of I-FABP and SP-D were comparable between all three groups. Categorisation of RA patients according to tobacco usage revealed the following significant positive correlations: LBP with C-reactive protein (p=0.0137); a trend (p=0.073) towards an association of LBP with the DAS 28-3 disease severity score; RF-IgG antibodies with both LPS and LBP (p=0.033 and p=0.041, respectively); aCCP-IgG antibodies with LPS (p=0.044); and aCCP-IgG with RF-IgM autoantibodies (p=0.0016). The findings of this study, several of them novel, imply that tobacco products, as opposed to microbial translocation, represent a potential source of LPS in this study cohort of RA patients, again underscoring the risks posed by tobacco usage for the development and severity of RA.

© Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ., Objectives: To compare consecutive disease modifying antirheumatic drug (DMARD)-treatment regimes in daily practice in patients with rheumatoid arthritis (RA) who failed on initial methotrexate, while using a multiple propensity score (PS) method to control for the spurious effects of confounding by indication. Methods: Patients with newly diagnosed RA who had failed initial treatment with methotrexate were selected from METEOR, an international, observational registry. Subsequent DMARD-treatment regimens were categorised as: (1) conventional synthetic DMARD(s) (csDMARD(s)) only (143 patients), (2) csDMARD(s)+glucocorticoid (278 patients) and (3) biological DMARD (bDMARD)±csDMARD(s) (89 patients). Multiple PS that reflect the likelihood of treatment with each treatment-regime were estimated per patient using multinomial regression. Linear mixed model analyses were performed to analyse treatment responses per category (Disease Activity Score (DAS)) after a maximum follow-up duration of 6 and 12 months, and results were presented with adjustment for the multiple PS. Results: After 6 months, follow-up PS-adjusted treatment responses yielded a change in DAS per year (95% CI) of -2.00 (-2.65 to -1.36) if patients received a bDMARD; of -0.96 (-1.33 to -0.59) if patients received csDMARD(s)+glucocorticoids and of -0.73 (-1.21 to -0.25) if patients received csDMARDs only. These changes were -0.91 (-1.23 to -0.60); -0.43 (-0.62 to -0.23) and -0.39 (-0.66 to -0.13), respectively after 1 year of follow-up. Conclusions: In this analysis of worldwide common practice data with adjustment for multiple PS, patients with RA who had failed initial treatment with methotrexate monotherapy had a better DAS-response after a subsequent switch to a bDMARD-containing treatment regimen than to a regimen with csDMARD(s) only, with or without glucocorticoids.