Organic solvents and Multiple Sclerosis: the doubled risk dilemma

BACKGROUND

Compensation for industrial disease in the UK may be obtained in two ways. A State scheme includes a list of accepted associations between occupations and diseases with evidence of a causative association. Epidemiological evidence of a doubled risk in the occupation concerned is usually required. This takes no account of variation of exposures within occupations, excluding many occupations where risk is less than doubled. In such cases, compensation for a perceived industrial illness may be obtained in Civil Courts, where excessive exposures can be considered.

AIMS

To show that in the Civil Courts evidence of excessive exposure may lead to compensation for diseases which are not yet compensable as Industrial Injuries in the UK and to draw attention to the association of multiple sclerosis (MS) with solvent exposure.

METHODS

We report the case of an industrial spray painter, who claimed his MS had been caused by high-level exposure to organic solvents, and our examination of the epidemiological evidence submitted.

RESULTS

The painter received compensation by an out-of-court settlement, despite the overall epidemiological risk in relation to solvent exposure having been shown to be less than doubled. The evidence hinged on individual risk in relation to high exposure, genetic susceptibility and demonstration of a plausible mechanism.

CONCLUSIONS

High organic solvent exposure may lead to the development of MS. Those giving evidence in Court need to be able to discuss the epidemiological and toxicological issues in relation to exposure in the individual case.

OP0267 A GENOME-WIDE INVESTIGATION OF PERSISTENCE TO TREATMENT WITH METHOTREXATE IN SWEDISH EARLY RHEUMATOID ARTHRITIS PATIENTS

Background

Despite being the anchor drug for treating rheumatoid arthritis (RA), methotrexate (MTX) provides a good response only in some of the treated patients [1]. If MTX treatment outcome has a substantial genetic component, genetic variants could provide useful predictors for identification of patients likely to respond and remain on treatment. So far, studies have focused mainly on primary response, and attempts to explain the inter-patient variability through genetic variants have been inconclusive or underpowered [2,3].

Objectives

We aimed to investigate whether there are genetic variants associated with persistence to treatment with MTX (at one and three years) in early RA, and to estimate any underlying heritability.

Methods

We conducted a genome-wide association study (GWAS) on persistence to treatment with MTX in DMARD-monotherapy. We included participants from the Epidemiological Investigation of RA (EIRA) study and the Swedish Rheumatology Quality Register’s biobank, diagnosed with early RA and treated with MTX as their first ever DMARD. Persistence to MTX was defined as remaining on treatment at one and three years, respectively, with no additional DMARDs added during that period. Estimation of SNP-based heritability was done using restricted maximum likelihood. We performed the analyses for all RA, and two disease subsets: those positive for either ACPA or rheumatoid factor, and those negative for both.

Results

After quality control, 3403 of an initial 3609 early RA patients of European ancestry and above five million SNPs remained for the primary analysis. Among these, 65% were persistent at one year, and 44% were persistent at three years. In secondary analysis we excluded 218 patients due to missing sero-status. Of the remaining, 72% were seropositive. No SNP reached genome-wide significance, neither for persistence at one nor at three years. The SNP-based heritability was estimated to 0.35 (95%CI 0.04-0.65) for persistence at one year and 0.09 (95%CI 0.00-0.37) for persistence at three years. Analyses stratified by sero-status provided results comparable to the main analysis with similar proportions of persistent patients and no SNP reaching genome-wide significance for any of the subgroups. Point estimates of heritability for persistence in the seropositive group at one year (h2 = 0.08, 95%CI 0.00-0.51) was lower than for seropositive persistence at three years (h2 = 0.19, 95%CI 0.00-0.62) while point estimates for the seronegative heritability were zero for both persistence outcomes.

Conclusion

Despite being the largest GWAS on an MTX treatment outcome to date, no genome-wide significant associations were detected. The low heritability observed along with the lack of strong independent associations, may indicate that genetic influence from common genetic variants on persistence to MTX is minor, and of a polygenic nature.

References

[1]Saevarsdottir, S., et al., Predictors of response to methotrexate in early DMARD naive rheumatoid arthritis: results from the initial open-label phase of the SWEFOT trial. Ann Rheum Dis, 2011. 70(3): p. 469-75.

[2]Ling, S., J. Bluett, and A. Barton, Prediction of response to methotrexate in rheumatoid arthritis. Expert Rev Clin Immunol, 2018. 14(5): p. 419-429.

[3]Szostak, B., et al., Using pharmacogenetics to predict methotrexate response in rheumatoid arthritis patients. Expert Opin Drug Metab Toxicol, 2020. 16(7): p. 617-626.

Acknowledgements

The authors would like to thank the participants of the EIRA study and the SRQ biobank as well as deCODE genetics for making this study possible.

Disclosure of Interests

Anton Öberg Sysojev: None declared, Saedis Saevarsdottir Employee of: Part-time employee of deCODE genetics Inc., Lina M. Diaz-Gallo: None declared, Lars Alfredsson: None declared, Lars Klareskog: None declared, - SRQ Biobank Group: None declared, Thomas Frisell: None declared, Leonid Padyukov: None declared, Johan Askling Grant/research support from: Karolinska Institutet has entered into agreements with the following companies, with JA as PI: Abbvie, BMS, Eli Lilly, Galapagos, Janssen, Pfizer, Roche, Samsung Bioepis and Sanofi., Helga Westerlind: None declared

POS0515 THE ASSOCIATION BETWEEN AUTOANTIBODIES AND RISK FOR VENOUS THROMBOEMBOLIC EVENTS AMONG PATIENTS WITH RHEUMATOID ARTHRITIS

Background

Patients with rheumatoid arthritis (RA) have an increased risk for cardiovascular disease, including venous thromboembolic events (VTE)1. The reason behind the increased VTE risk is incompletely understood, but inherent features of RA, such as RA specific autoantibodies, could potentially play a role. For example, studies have linked occurrence and levels of rheumatoid factor (RF) in the general population to increased VTE risk2. We and others have demonstrated an association between ACPA and risk of later ischemic cardiovascular events3. There are also potential mechanistic links; citrullinated fibrinogen (cFib) has been associated to clot stability4.

Objectives

We aimed to examine the association between anti-modified protein antibodies (AMPAs) and risk of VTE in RA.

Methods

We included 2809 individuals newly diagnosed with RA and included in the Swedish EIRA study 1996-2009. Through linkage to nationwide health care registers we identified past and incident events of VTE based on validated ICD code algorithms. We centrally typed baseline sera for anti-CCP2, 20 different ACPA sub-specificities, RF isotypes, carbamylated antibodies and 10 additional post-translational modifications. We followed all individuals from RA diagnosis up until their first ever VTE event, migration, death or end of study (2020-12-31) whichever occurred first. We used a Cox regression to estimate hazard ratios (HR) with 95% confidence intervals (CI). Individuals with a history of a VTE event (n=27) at RA diagnosis were excluded.

Results

We included 2782 individuals; 72% were women, median age at RA diagnosis was 54 years (inter quartile range (IQR) 18 years) and median follow-up time was 15.5 (IQR 6.8) years. During follow-up 177 incident VTE events were observed corresponding to an incidence of 5.0 per 1,000 person years.

1797 (64.6%) patients were positive for IgG anti-CCP2 and the HR for VTE (vs. being negative for anti-CCP2) was 1.33 (95%CI 1.00-1.78). The risk of VTE increased with the level of anti-CCP2, with an HR of 1.49 (95%CI 0.99-2.22) for the group with extreme levels compared to those negative for anti-CCP2 (p-value for trend 0.048). For IgA anti-CCP2 the HR was 1.35 (95% CI 0.99-1.84) when comparing those expressing IgA anti-CCP2 against those who did not.

Of 20 ACPA fine-specificities studied, 18 occurred with a frequency > 10% in our sample. The median number of fine-specificities expressed was 6 (IQR 11). The risk of VTE increased with the number of ACPA fine-specificities expressed (p-value for trend 0.033). At the 0.05 significance level, two fine-specificities were each associated with VTE; cPept Z1 [HR=1.40 (95%CI 1.06-84)] and cPept-1 [HR=1.47 (95%CI 1.12-1.93)]. None of the six antibodies against cFib assessed were statistically significantly associated with VTE risk. No associations were observed for other AMPAs. Among the three RF isotypes, only IgM RF was statistically associated with VTE [HR=1.38 (95%CI 1.04-1.83)].

Conclusion

RA-related antibodies analysed in clinical practice (anti-CCP2 IgG, RF) are associated not only with risk of myocardial infarction, stroke and cardiovascular death as previously demonstrated but also with VTE. There were no clear specific signals with ACPA fine-specificities, other AMPAs, or IgA RA autoantibodies.

References

[1]Holmqvist ME,et al. Risk of venous thromboembolism in patients with rheumatoid arthritis and association with disease duration and hospitalization. JAMA. 2012;308(13):1350-6.

[2]Meyer-Olesen CL, et al. Increased rheumatoid factor and deep venous thrombosis: 2 cohort studies of 54628 individuals from the general population. Clin Chem. 2015;61(2):349-59.

[3]Westerlind H, et al. Anti-citrullinated protein antibody specificities, rheumatoid factor isotypes and incident cardiovascular events in patients with rheumatoid arthritis. Arthritis Rheumatol. 2020.

[4]Maners J, et al. A Mendelian randomization of gamma’ and total fibrinogen levels in relation to venous thromboembolism and ischemic stroke. Blood. 2020;136(26):3062-9.

Disclosure of Interests

Helga Westerlind: None declared, Alf Kastbom: None declared, Johan Rönnelid: None declared, Monika Hansson: None declared, Lars Alfredsson: None declared, Linda Mathsson-Alm Employee of: LMA an employee of Thermo Fisher Scientific producing the ACPA sub-specificity test, Guy Serre: None declared, Martin Cornillet: None declared, Rikard Holmdahl Consultant of: historically several. Currently paid advisor for Lipum AB and Cyxone AB, Per-Johan Jakobsson Consultant of: UCB – Nov 2021 to Feb 2022., Karl Skriner: None declared, Holger Bang Employee of: HB is an employee of Orgentec Diagnostica, an IVRc company, Lars Klareskog: None declared, Saedis Saevarsdottir Employee of: SS is a part-time employee of deCODE genetics Inc., Karin Lundberg: None declared, Caroline Grönwall: None declared, Johan Askling Grant/research support from: AbbVie, AstraZeneca, Bristol Myers Squibb, Eli Lilly, Janssen, Merck, Pfizer, Roche, Samsung Bioepis, Sanofi, and UCB.

Season of birth is associated with multiple sclerosis and disease severity

BACKGROUND

The latitude gradient in multiple sclerosis incidence indicates that low sun exposure and therefore vitamin D deficiency is associated with multiple sclerosis risk.

OBJECTIVE

Investigation of the effect of month of birth, which influences postnatal vitamin D levels, on multiple sclerosis risk and severity in Sweden.

METHODS

Patients and population-based controls were included from three nationwide cohorts. Differences in month of birth between cases and controls were analyzed using logistic regression and examined for effect modification by calendar year and geographic region at birth.

RESULTS

Males had a reduced risk of multiple sclerosis if born in the winter and increased risk if born in the early fall. Individuals born before 1960 had an increased risk if born in summer or fall. Being born in late summer and early fall was associated with more severe disease.

CONCLUSIONS

We identified a birth cohort effect on the association between the month of birth and multiple sclerosis, with a more significant effects for births before 1960. This coincides with a period of lower breastfeeding rates, recommended intake of vitamin D, and sun exposure, resulting in a lower vitamin D exposure during the fall/winter season for infants born in the summer.

POS0009 THE RELATIONSHIP BETWEEN DIFFERENT IGG AND IGA ANTI-MODIFIED PROTEIN AUTOANTIBODIES IN RHEUMATOID ARTHRITIS

Background:

Seropositive rheumatoid arthritis (RA) is characterized by the presence of rheumatoid factor (RF) and anti-citrullinated protein autoantibodies (ACPA) with different fine-specificities. Yet, other serum anti-modified protein autoantibodies (AMPA), e.g. anti-carbamylated (Carb), anti-acetylated (KAc), and anti-malondialdehyde acetaldehyde (MAA) modified protein antibodies, have been described. By using RA patient single-cell derived monoclonal antibodies we have previously shown that individual ACPA clones recognize small distinct citrulline-containing epitopes giving them extensive multireactivity when these epitopes are found in many peptides and proteins. Moreover, certain CCP2+ multireactive ACPA clones bind also to cabamylated and acetylated autoantigens [1].

Objectives:

To provide a comprehensive evaluation of serum IgG and IgA autoreactivity to different post-translational modifications in RA.

Methods:

We analyzed 30 different IgG and IgA AMPA reactivities to modified antigens by ELISA and autoantigen arrays, in N=1985 newly diagnosed RA patients and population controls. The study utilized both previously established (i.e IgG and IgA CCP2; IgG ACPA fine-specificities; IgG anti-Carb fibrinogen and Carb FCS; IgG and IgA Cit/Carb/KAc/Orn(Ac)-vimentin), and novel assays (e.g. IgG anti-MAA and IgG anti-acetylated histones). Association with patient characteristics such as smoking and disease activity were explored. The newly developed assays were also evaluated in SLE disease controls and CCP2+ RA-risk individuals without arthritis.

Results:

Carb and KAc reactivities by different assays were primarily seen in patients also positive for citrulline-reactivity. Modified vimentin (mod-Vim) peptides were used for direct comparison of different AMPA reactivities, revealing that IgA AMPA recognizing mod-Vim was mainly detected in subsets of patients with high IgG anti-Cit-Vim levels and a history of smoking. IgG acetylation reactivity was mainly detected in a subset of patients with Cit and Carb reactivity. Anti-acetylated histone 2B reactivity was RA-specific and associated with high anti-CCP2 IgG levels, multiple ACPA fine-specificities, and smoking. This reactivity was also found to be present in CCP2+ RA-risk individuals without arthritis. Our data further demonstrate that IgG autoreactivity to MAA was increased in RA compared to controls with highest levels in CCP2+ RA, but was not RA-specific, and showed low correlation with other AMPA. Anti-MAA was instead associated with disease activity and was not significantly increased in CCP2+ individuals at risk of RA. Notably, RA patients could be subdivided into four different subsets based on their AMPA IgG and IgA reactivity profiles.

Conclusion:

We conclude that autoantibodies exhibiting different patterns of ACPA fine-specificities as well as Carb and KAc reactivity are present in RA and may be derived from multireactive B-cell clones. Anti-Carb and anti-KAc could be considered reactivities within the “Cit-umbrella” similar to ACPA fine-specificities, while MAA is distinctly different.

References:

[1]Sahlström P, Hansson M, Steen J, Amara K, Titcombe PJ, Forsström B, Stålesen R, Israelsson L, Piccoli L, Lundberg K, Klareskog L, Mueller DL, Catrina AI, Skriner K, Malmström V, Grönwall C. Different Hierarchies of Anti-Modified Protein Autoantibody Reactivities in Rheumatoid Arthritis. Arthritis Rheumatol. 2020 Oct;72(10):1643-1657. PMID: 32501655

Caroline Grönwall: None declared, Lisa Liljefors: None declared, Holger Bang Employee of: Employee at ORGENTEC Diagnostika GmbH, Aase Hensvold: None declared, Monika Hansson: None declared, Linda Mathsson-Alm Employee of: Employee at Thermo Fisher Scientific, Lena Israelsson: None declared, Anna Svärd: None declared, Cyril CLAVEL: None declared, Elisabet Svenungsson: None declared, Iva Gunnarsson: None declared, Guy Serre: None declared, Saedis Saevarsdottir: None declared, Alf Kastbom: None declared, Lars Alfredsson: None declared, Vivianne Malmström: None declared, Johan Rönnelid: None declared, Anca Catrina: None declared, Karin Lundberg: None declared, Lars Klareskog: None declared

OP0236 THE EFFECT OF UV-B RADIATION EXPOSURE ON THE RISK OF DEVELOPING RHEUMATOID ARTHRITIS

Background:

UV-B radiation has known immunomodulatory properties, but to what extent UV-B radiation exposure might affect the occurrence of rheumatoid arthritis (RA) has been relatively little studied, and with partially contradictory results.

Objectives:

To investigate the association between sun- and travel habits, as proxy markers for UV-B radiation exposure, and risk of incident RA, overall and by RA subtype.

Methods:

We performed a matched case-control study of 1151 incident cases with new-onset RA and 2374 population controls from the Swedish Epidemiological Investigation of Rheumatoid Arthritis (EIRA) study, recruited between 2006 and 2017. The association between sunbathing frequency, solarium use, and frequency of travels to sunnier countries than Sweden (exposures) and risk of RA (outcome) were assessed as odds ratios (OR) with 95 % confidence intervals (CI) through logistic regression, and adjusted for age, sex, residential region, year of study entry, body mass index, education, income, smoking and alcohol consumption. We further assessed effect modification by self-reported skin type, income and education, and by rheumatoid factor (RF) serostatus.

Results:

Overall, the frequency of sunbathing, and solarium use, were similar among RA cases and controls: ‘never doing sunbathing’ amongst RA cases vs. controls: 22% vs. 21 %, ‘sunbathing daily when possible’: 10% vs. 12%, and solarium use 13% vs. 12%. The proportion of ‘not travelled abroad to a sunnier country than Sweden during the past 5 years’ was higher for RA cases than controls: 27% vs. 23%, and ‘travelling abroad more than once a year’ was less common among RA cases: 15% vs. 20%.

Sunbathing frequency was not linked to risk of RA (OR 0.91, 95% CI 0.69-1.20), nor was solarium use (OR 1.07, 95% CI 0.85-1.35). Stratification by skin type revealed no major effect modification, nor did stratification by RF status. In contrast, frequency of travel to sunnier countries than Sweden was inversely associated with RA risk comparing the most to least frequent travelers (OR 0.68, 95% CI 0.54-0.87). When stratified by educational level, this association was confined to individuals with medium (OR 0.69, 95% CI 0.48-0.98) or high (OR 0.60, 95% CI 0.50-0.91) and absent among subjects with low education (OR 1.10, 95% CI 0.56-1.99). No such interaction was observed between travel habits and income.

Table 1.

RA cases and controls with adjusted odds ratios and confidence intervals for overall risk of RA and by RA serostatus.

NOR* for RA (95% CI)Exposure variableRA casesControlsRF+RF-All RARF+RF-SunbathingaNever24949516185refrefrefAt least once a month3988442651241.05 (0.85-1.29)1.07 (0.84-1.36)0.98 (0.72-1.34)At least once a week3767512391301.11 (0.90-1.38)1.07 (0.83-1.37)1.21 (0.88-1.66)Daily12027875430.91 (0.69-1.20)0.86 (0.62-1.20)0.96 (0.64-1.46)TravelbNever314537208103refrefRefSeldom294568193970.98 (0.79-1.21)0.98 (0.77-1.25)0.98 (0.71-1.35)Once a year3598052271210.82 (0.67-1.01)0.80 (0.63-1.02)0.83 (0.61-1.13)More than once a year176463112610.68 (0.54-0.87)0.68 (0.51-0.91)0.70 (0.48-1.01)SolariumcNever9912083634336refrefRefOnce per year or more153290107461.07 (0.85-1.35)1.08 (0.83-1.40)1.11 (0.77-1.59)

OR = adjusted odds ratio, CI = confidence interval, N = number of participants, RA = rheumatoid arthritis, ref = reference, RF= rheumatoid factor. a Frequency of sunbathing if the weather invites to it? b Frequency of travels to a country sunnier than Sweden in the last 5 years? c Frequency of solarium use in the last 5 years? *Adjusting for age, sex, region, index year, BMI, smoking, alcohol consumption, education level and income. <4 % of data was missing for all variables.

Conclusion:

Proxy markers for UV-B exposure (sunbathing frequency and solarium use within the past five years) do not seem to be strong risk factors for RA. Frequency of travels abroad was inversely associated to RA risk. The nature behind this association remains unclear.

Disclosure of Interests:

Johanna Hagman: None declared, Bénédicte Delcoigne: None declared, Lars Klareskog: None declared, Lars Alfredsson: None declared, Johan Askling Grant/research support from: JA acts or has acted as PI for agreements between Karolinska Institutet and the following entities, mainly in the context of the ARTIS national safety monitoring programme of immunomodulators in rheumatology: Abbvie, BMS, Eli Lilly, Merck, MSD, Pfizer, Roche, Samsung Bioepis, Sanofi, and UCB Pharma

POS0355 ASSOCIATIONS BETWEEN HLA-DRB1 SHARED EPITOPES ALLELES AND ANTI-RA33 ANTIBODIES IN DIFFERENT SUBSETS OF RHEUMATOID ARTHRITIS IN MALAYSIAN POPULATION

Background:

The mechanisms affecting anti-RA33 antibody’s involvement in RA pathogenesis is still unclear. Refining our understanding of anti-RA33’s role in RA in relation to known RA-associated genes and serological elements is needed.

Objectives:

We investigated the relationship between RA-associated HLA-DRB1 epitope (SE) allele and presence of anti-RA33 antibodies in different serological subsets of rheumatoid arthritis in a Malaysian population.

Methods:

Serum samples from 550 RA cases comprising seronegative (negative for anti-CCP2, IgG and IgM, n=250), seropositive (triple-autoantibody positive, n=150), singular anti-CCP2 positive (n=100), and double RF positive RA (n=50) were chosen from the Malaysian Epidemiological Investigations of RA (MyEIRA) case-control study. Three hundred MyEIRA population controls were used for comparison. All serum samples were assayed using a commercial anti-RA33 ELISA kit. All genetic samples were genotyped for four-digit HLA-DRB1 alleles using the PCR-SSO method on Luminex platform.

Results:

The proportions of anti-RA33 positive was 20.9% in all RA cases (i.e. 34% in RF only positive RA; 25% in seropositive RA; 18% in seronegative RA and 18% in anti-CCP2 only positive RA). The HLA-DRB1 shared epitope alleles were significantly associated with anti-RA33 positive in the seropositive RA subgroup (OR=6.9, 95% CI 1.4-34.8; p=0.02). We observed significant association between anti-RA33 negative and HLA-DRB1 SE alleles among the seropositive RA patients (OR=4.5, 95% CI 2.8-7.2; p<0.001) and among CCP only positive RA (OR=4.4; 95% CI 2.6-7.4; p<0.01). No association was observed between anti-RA33 status and HLA-DRB1 SE alleles in seronegative RA and RF only positive RA.

Conclusion:

The HLA-DRB1 SE alleles increased the risk of seropositive and CCP only positive RA independent of anti-RA33 positivity.

References:

[1]Boeters, Debbie M et al. “The 2010 ACR/EULAR criteria are not sufficiently accurate in the early identification of autoantibody-negative rheumatoid arthritis: Results from the Leiden-EAC and ESPOIR cohorts.” Seminars in arthritis and rheumatism vol. 47,2 (2017): 170-174.

[2]de Brito Rocha, Sara et al. “Clinical and pathophysiologic relevance of autoantibodies in rheumatoid arthritis.” Advances in rheumatology (London, England) vol. 59,1 2. 17 Jan. 2019.

Acknowledgements:

The authors would like to thank the Director General of Health, Ministry of Health Malaysia for supporting this study. The authors are also indebted to participants for their kind participation. This study was financially supported by the Ministry of Health, Malaysia (JPP-IMR 08-012).

Disclosure of Interests:

None declared

POS0484 THE ASSOCIATION BETWEEN SOCIAL STRESSORS AND DISEASE REMISSION AMONG MEN AND WOMEN WITH EARLY RHEUMATOID ARTHRITIS

Background:

The role of psychosocial conditions on the disease course of rheumatoid arthritis (RA) is getting increased attention. In our previous study, low social support and low decision latitude at work were associated with known modifiable risk factors for RA disease development, such as smoking and low educational level (1). Further, smoking and low educational level have previously been shown to be associated with worse RA disease outcome (2-4). Whether psychosocial characteristics are related to RA disease outcome needs further investigation.

Objectives:

To investigate the relationship between two psychosocial characteristics: low social support and low decision latitude at work, and achievement of remission in patients with RA.

Methods:

At inclusion in the Swedish EIRA study, incident RA cases (N=3724) and controls (N=5937), matched for age, sex and residential area, responded to a questionnaire including questions on social support and decision latitude at work. The answers were recoded into separate scores and the distribution of the scores among controls were used to define the exposures. Low social support and low decision latitude at work, respectively, among patients, were set as the level corresponding to the lowest quartile among controls, and were compared with scores corresponding to the remaining three quartiles.

The outcome, disease activity score 28-joint count (DAS28) remission, defined as DAS28<2.6, was captured through linkage with the Swedish Rheumatology Quality Register (SRQ) with data available from diagnosis for 2693 out of 3700 cases for social support and for 847 out of 1248 cases for decision latitude at work.

Logistic regression was used to evaluate the association between low social support or low decision latitude at work, respectively, and the chance of remission at the time-points 3 months, 12 months and 60 months after inclusion. All results were adjusted for age, sex and residential area and the fully adjusted models were also adjusted for smoking, obesity, physical activity and educational level.

Results:

Low social support (n=655) was associated with a reduced chance for remission at all three time points in the model adjusted for age, sex and residential area; OR 3 months 0.77 (95% CI 0.61-0.97), OR 12 months 0.78 (95% CI 0.64-0.95) OR 60 months 0.77 (95% CI 0.59-0.99). This association was diminished after further adjustment. After stratifying for sex, this association was enhanced in women but inverse among men (Figure 1).

No association between low decision latitude at work (n=166) and chance for remission was observed neither in the analyses stratified for matching variables, nor in the full model. This result was only marginally changed after stratifying for sex (Figure 1).

Conclusion:

Low social support was associated with lower chance of remission in early RA, but the association was not independent of other risk factors for worse outcome (smoking, physical activity, obesity and low educational level).

The interrelationship between social stressors and previously known risk factors for worse outcome highlights the importance of supportive actions at many levels to increase the possibility for the individual to make healthy decisions.

References:

[1]Hedenstierna. et al. Scand J Rheumatol. 2021:1-5.

[2]Saevarsdottir, et al. Ann Rheum Dis. 2011;70(3):469-75.

[3]Saevarsdottir, et al. Arthritis Rheum. 2011;63(1):26-36.

[4]Jiang, et al. Arthritis Res Ther. 2015;17:317.

Figure 1.

Odds ratios for assiciation between social stressors and DAS 28 remission

Acknowledgements:

We want to thank all the participants of the EIRA study and the clinical collaborators for their valuable contribution. We also want to thank the staff for their dedicated work with the data collection.

Disclosure of Interests:

None declared

OP0096 EXPOSURE TO DENGUE INFECTION DO NOT RAISE RISK OF RHEUMATOID ARTHRITIS: FINDINGS FROM THE MALAYSIAN EPIDEMIOLOGICAL INVESTIGATION OF RHEUMATOID ARTHRITIS (MYEIRA) CASE-CONTROL STUDY

Background:

Dengue infection is associated with joints pain mimicking disease onset symptom of rheumatoid arthritis (RA). However, there is lack of epidemiological studies on exposure to dengue infection and risk of future RA.

Objectives:

We investigated the relationship between exposure to dengue infection and risk of developing different subsets of RA, defined by the presence of anti-citrullinated peptide antibody (ACPA) in the multi-ethnic Malaysian population.

Methods:

Serum samples from 1,235 RA cases (i.e. 516 Malay, 254 Chinese, 405 Indians and 60 others/mixed-ethnicity) and 1,624 epidemiological matched population-based controls (i.e. 1,023 Malay, 208 Chinese, 297 Indians and 96 others/mixed-ethnicity) were assayed for presence of dengue IgG antibody using World Health Organization recommended ELISA kits. Positive results of dengue IgG antibodies indicates previous exposure to dengue infection(s). We performed chi-square and Mann-Whitney U analysis to determine the association of ever-exposed dengue infection with ACPA-positive/ACPA-negative RA and to investigate the antibody frequency and levels among the studied populations.

Results:

We observed high occurrence of dengue IgG antibody in the overall RA cases (79.7%) and matched controls (77.3%), with no significant differences detected between the ACPA subsets of RA. Ethnicity stratification analysis revealed a decrease risk of developing ACPA-positive RA in the Indian patients with positive dengue IgG antibody (OR=0.59, 95% CI=0.37-0.94, p=0.03), and in particular patients with elevated level of dengue IgG antibody (OR=0.44, 95% CI=0.25-0.78, p<0.05). On the other hand, the significant decrease mean levels of dengue IgG antibody were observed in the ACPA-positive RA subset for all three major ethnic groups (i.e. Malay, p<0.0001, Chinese, p<0.01 and Indian<0.05) (Figure 1). No association was observed between presence of dengue IgG antibody and ACPA-negative RA subset.

Figure 1.

Comparison of mean dengue IgG antibody level between ever-exposed dengue infection RA cases, stratified by ACPA status. Comparison of median dengue IgG antibody level between the ever-exposed dengue infection ACPA-positive RA and normal controls in the four ethnic groups. The red line indicates the mean level of dengue IgG antibody level

Conclusion:

Our findings demonstrated that exposure to dengue infection do not increase the risk of developing future RA in the multi-ethnic Malaysian population. The inverse associations observed in the Indian ethnic group are in line with the other studies investigating exposure to viral infection and risk of RA.

References:

[1]Sherina et al (2017) Low levels of antibodies against common viruses associate with anti-citrullinated protein antibody-positive rheumatoid arthritis; implications for disease aetiology. Arthritis Research & Therapy 2017, 19:2169

[2]Gissel García et. al. (2011) Long-term persistence of clinical symptoms in dengue-infected persons and its association with immunological disorders. International Journal of Infectious Diseases 15 (2011) e38–e43

Acknowledgements:

The authors would like to thank the Director General of Health, Ministry of Health Malaysia for supporting this study. The authors are also indebted to participants for their kind participation. This study was financially supported by the Ministry of Health, Malaysia (JPP-IMR 17-025) and the short-term research grant by UniKL RCMP (str16037).

Disclosure of Interests:

None declared

POS0457 CHANGES OF RF ISOTYPE PROFILE IN PATIENTS WITH RHEUsMATOID ARTHRITIS: DATA FROM 10 YEARS FOLLOW-UP STUDY

Background:

Presence of autoantibodies such as anti-cyclic citrullinated peptide (anti-CCP2) and rheumatoid factor (RF) is of considerable diagnostic and prognostic value in patients with rheumatoid arthritis (RA). Limited data are available for autoantibody profile changes over time in patients with RA.

Objectives:

Thus, we compared the presence of anti-CCP2 and different RF isotypes in individual RA patients at baseline and during 10 years follow-up.

Methods:

A total of 320 RA patients from the Malaysian Epidemiological Investigation of Rheumatoid Arthritis (MyEIRA) case-control study was included in this study. The presence of anti-CCP2, IgM RF, IgG RF, and IgA RF at baseline and at later time point (±10 years) were determined using enzyme-linked immunosorbent assays, with identical techniques in paired samples. Seropositive RA is defined by the presence of at least one autoantibody, whilst seronegative RA is defined by the absence of all investigated autoantibodies.

Results:

The proportion of seropositive RA were higher for the follow-up samples (n=263, 82.2%) as compared to the baseline samples (n=251, 78.4%). Among the baseline samples, 105 (41.8%) were positive for anti-CCP2 and all RF isotypes. Of these individuals, 85 (81.0%) remained positive for all antibodies at the follow-up, while 20 (19.0%) lost one or more RF isotypes (4 IgM RF, 19 IgG RF and 13 IgA RF). Interestingly, 14 (5.6%) RA patients who were seropositive at baseline became totally seronegative after follow-up. Among the 69 patients seronegative at baseline, 26 (37.7%) acquired one or more autoantibodies at follow-up (14 IgM RF, 2 IgG RF, 9 IgA RF and 8 anti-CCP2) (Figure 1).

Conclusion:

Anti-CCP2 present at baseline usually remained at follow-up. Among Malaysian RA patients, changes in status were mainly found for RF of all isotypes.

References:

[1]Barra, Lillian et al. “Lack of seroconversion of rheumatoid factor and anti-cyclic citrullinated peptide in patients with early inflammatory arthritis: a systematic literature review.” Rheumatology (Oxford, England) vol. 50,2 (2011): 311-6.

[2]van Delft, Myrthe A M, and Tom W J Huizinga. “An overview of autoantibodies in rheumatoid arthritis.” Journal of autoimmunity vol. 110 (2020): 102392.

Figure 1.

Comparison of serum autoantibody profile in rheumatoid arthritis patients during baseline enrolment and 10 years follow-up.

Acknowledgements:

The authors would like to thank the Director General of Health, Ministry of Health Malaysia for supporting this study. The authors are also indebted to participants for their kind participation. This study was financially supported by the Ministry of Health, Malaysia (JPP-IMR 08-012; 18-051).

Disclosure of Interests:

None declared

AB0054 IS TEA CONSUMPTION ASSOCIATED WITH RISK OF RHEUMATOID ARTHRITIS?

Background:

Only few studies have looked at the association between tea consumption and risk of rheumatoid arthritis (RA) with inconclusive results.

Objectives:

To estimate the association between tea consumption and risk of RA in a large population-based case-control study.

Methods:

We used data from the Swedish Epidemiological Investigation of RA (EIRA), a population-based case-control study including incident RA cases with 2 controls randomly matched from the general population, based on age, sex and residential area at the date of diagnosis. All participants filled in a comprehensive questionnaire on lifestyle factors, including a 124-item food frequency questionnaire (FFQ). Data from October 2005 - May 2018 was used.

Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated using conditional logistic regression, overall and stratified by anti-citrullinated protein antibody (ACPA) and smoking status. We adjusted for smoking status, coffee and alcohol consumption, educational level and BMI. The dose-response trend of the association between tea consumption and risk of rheumatoid arthritis was estimated using restricted cubic spline with knots at 0, 0.29, and 2.29 cups per day. Missing tea values (44.8%) were imputed based on the zero-consumption assumption. A sensitivity analysis was performed to evaluate the influence of the assumption on the main result, with 70% of the missing randomly imputed as no consumption, and the remaining 30% randomly assigned to the other categories (10% per category).

Results:

We included 2237 cases and 4661 controls. Controls were more likely to drink ≥2 tea cups/day compared to RA cases (22.1% vs. 19.7%).

The crude odds of developing RA was 22% lower (OR=0.78, 95% CI: 0.66-0.92) among those who consumed ≥2 tea cups/day compared to those who drank <1 cup/day (irregular drinkers). After adjustment for covariates, the inverse association was less pronounced and only borderline significant (OR=0.85, 95% CI: 0.71-1.01). A similar OR was observed among non-tea consumer (OR=0.82, 95% CI: 0.70-0.95). The odds of developing ACPA positive RA (but not ACPA negative) was statistically significant lower among participants drinking >=2 cups/day compared to irregular tea drinkers (OR=0.76, 95% CI: 0.62-0.94). In analyses stratified by smoking, an inverse association between tea intake and RA was found only among current smokers (OR=0.58, 95% CI: 0.37-0.92), while no association was found in never smoker. The sensitivity analysis showed results similar to the main analysis, although the OR in the no consumption category was not significant (OR=0.88, 95% CI: 0.76-1.02) while the OR in the highest category was statistically significant (OR=0.85, 95% CI: 0.73-0.99).

Overall tea consumption0 cups/day<1 cup/day1-2 cups/day>=2 cups/dayOverall Number955/1941453/847388/845441/1028 OR crude*0.89 (0.77-1.03)Ref0.84 (0.71-1.00)0.78 (0.66-0.92) OR adjusted±0.82 (0.70-0.95)Ref0.87 (0.73-1.04)0.85 (0.71-1.01)ACPA positive Number637/1156321/527268/501277/630 OR adjusted0.81 (0.67-0.97)Ref0.88 (0.71-1.09)0.76 (0.62-0.94)ACPA negative Number312/571129/221119/251162/288 OR adjusted0.87 (0.66-1.14)Ref0.87 (0.63-1.19)1.07 (0.78-1.46)Never smokers Number290/859164/436142/433213/563 OR adjusted0.90 (0.72-1.14)Ref0.88 (0.68-1.15)1.04 (0.81-1.33)Current smokers Number296/37189/9659/7859/99 OR adjusted0.81 (0.57-1.14)Ref0.83 (0.52-1.31)0.58 (0.37-0.92)Figure 1.

Dose-response odds ratio for risk of rheumatoid arthritis (RA) by tea consumption.

Conclusion:

In this large population-based case-control study, high tea consumption, as well as no consumption, was associated with a decreased risk to develop ACPA positive, but not negative, RA, when compared to irregular tea drinking (<1 cup/day). The inverse association between high tea consumption and RA was lowest in analyses restricted to current smokers.

Disclosure of Interests:

Helga Westerlind: None declared, Ida Palmqvist: None declared, Saedis Saevarsdottir Employee of: part-time employee of deCODE genetics, Lars Alfredsson: None declared, Lars Klareskog: None declared, Daniela Di Giuseppe: None declared

Widespread non-joint pain in early rheumatoid arthritis

Objective: The aim of the study was to assess the development of widespread non-joint pain (WNP) in a cohort of patients with early rheumatoid arthritis (RA), the associated health-related quality of life (HRQoL), and clinical and demographic risk factors for WNP.Method: Incident cases with RA, from the Swedish population-based study Epidemiological Investigation of Rheumatoid Arthritis (EIRA), with a follow-up of at least 3 years, constituted the study population. WNP was defined as pain outside the joints in all four body quadrants and was assessed at the 3 year follow-up. Patients who reported WNP were compared to patients without WNP regarding HRQoL, measured by the Short Form-36, at 3 years, and clinical and demographic characteristics at the time of RA diagnosis.Results: A total of 749 patients constituted the study sample, of whom 25 were excluded after reporting already having severe pain before RA diagnosis. At the 3 year follow-up, 8% of the patients reported having WNP as well as statistically significant worse HRQoL. At the time of RA diagnosis, the patients with WNP had worse pain and pain-related features, while no difference was seen in the inflammatory parameters.Conclusion: WNP occurs in a substantial subset of patients with RA, also early in the course of the disease, and the HRQoL for these patients is significantly reduced. Patients who develop WNP at 3 years are already distinguishable at the time of diagnosis by displaying more pronounced pain ratings together with an average level of inflammatory disease activity.

Social stressors and risk of rheumatoid arthritis and their relationship to known modifiable risk factors: results from the Swedish EIRA study

Objectives: To investigate whether low social support or low decision latitude at work correlate with risk of rheumatoid arthritis (RA), and whether and how those factors are associated with known modifiable risk factors for RA.Method: The Swedish population-based EIRA study included, from 1996 to 2015, 3724 incident RA cases and 5935 controls, matched for age, gender, and residential area. Participants filled in detailed questionnaires at diagnosis. Using logistic regression, we investigated whether low social support and low decision latitude at work were associated with RA risk, and whether and how these exposures are associated with known modifiable risk factors for RA.Results: Low decision latitude at work was associated with RA risk in unadjusted analyses [odd ratio (OR) = 1.52, 95% confidence interval (CI) = 1.20-1.94], but this association was weakened after adjustment for known RA risk factors (adjusted OR = 1.24, 95% CI = 0.93-1.63). Low social support was not associated with RA risk (unadjusted OR = 1.05, 95% CI = 0.95-1.15). Cases reporting low decision latitude were more often smokers (OR = 2.05, 95% CI = 1.33-3.16), without university degrees (OR = 8.23, 95% CI = 5.13-13.22), and more often female (OR = 2.52, 95% CI = 1.66-3.81), with a similar pattern among controls. Cases reporting low social support were more often men (OR = 1.60, 95% CI = 1.40-1.83), smokers (OR = 1.46, 95% CI = 1.26-1.70), obese (OR = 1.29, 95% CI = 1.09-1.54), physically inactive (OR = 2.78, 95% CI = 1.98-3.90), and without university degrees (OR = 2.04, 95% CI = 1.77-2.36), with a similar pattern among controls.Conclusion: Low decision latitude coexisted with several known environmental/social risk factors for RA, together defining groups of individuals at increased risk of RA. These risk factors should be viewed in context when testing actions to diminish RA risk in prospective studies.

Cotinine as a measure of smoking in observational studies of multiple sclerosis

Studies using cotinine levels to define smokers have generally failed to detect an association between smoking and multiple sclerosis (MS). Using a Swedish population-based case-control study, we show that associations in relation to MS risk and progression differ considerably depending on how smoking is measured. The risk of conversion into secondary progressive disease was increased among smokers when self-reported smoking history, but not presumed cotinine levels, was used to define smokers. Defining smoking by cotinine levels without distinguishing between different sources of nicotine may lead to severely biased estimates of the association between smoking and both MS risk and progression.

Stressful life events are associated with the risk of multiple sclerosis

BACKGROUND AND PURPOSE

Unexpected stressful life events may alter immune function and affect susceptibility to autoimmune diseases including multiple sclerosis (MS). Current results from epidemiological investigations examining the role of stress in MS remain inconsistent. The aim was to conduct the hitherto largest population-based case-control study on this topic.

METHODS

Extensive questionnaire information collected on lifestyle environmental factors available for 2930 incident MS cases and 6170 controls were used to assess the association of 10 major life events that had occurred before disease onset with the risk of MS by unconditional logistic regressions, adjusting for potential confounders. Stratified analyses were also performed by sex and time.

RESULTS

Compelling evidence was found for a link between major life events and risk of MS - most events significantly increased disease risk by 17%-30%. It was further observed that women were affected to a greater extent than men under certain stressful scenarios, and that most events that happened recently (≤5 years prior to MS onset) had significant effects on MS, indicating a critical window in disease development.

CONCLUSION

Stressful life events may have an adverse effect on the risk of MS. Research into the mechanisms of this observation may give important clues to triggering pathogenetic events in MS.

FRI0082 SLEEP PROBLEMS IN EARLY RHEUMATOID ARTHRITIS

Background:

It is well known that patients with established RA suffer from problems with sleep quality[1]. There are however few, if any, studies on sleep quality among newly diagnosed patients.

Objectives:

To investigate the sleep quality among patients newly diagnosed with RA.

Methods:

We used the Swedish study Epidemiological Investigation of RA (EIRA) including patients at the time of diagnosis, based on the 1987 ACR criteria during 2008-2016. At 1 and 3 years after diagnosis, the patients were sent a questionnaire in which they were asked to rate their sleep quality on 10 different questions. We then calculated 6 different sleep components consisting of insomnia, non-restorative sleep, sleep problems, general quality of sleep, if poor sleep affected the health and if they were getting enough sleep[2].

Sleep problems were defined as mostly or always having problems with either of the following: falling asleep, many awakenings with difficulties to go back to sleep, waking up early or having disturbed/restless sleep. Insomnia was defined as answering mostly or always on either problem with falling asleep, many awakenings with difficulties to go back to sleep or waking up early, in combination with mostly or always being tired during the day.

Having problems with non-restorative sleep was defined as mostly or always having trouble waking up or not feeling well rested when waking up. We defined having problem with not getting enough sleep, sleep quality affecting the health and poor sleep quality as reporting any of the two highest scores on the corresponding questions.

We then calculated the proportion of people experiencing no problems at 1 or 3 years after RA diagnosis, developing problems, improving or always having problems with their sleep.

Results:

We identified 1483 patients with data at either one or both time points. The mean age was 59 years (IQR 19), and 1063 (72%) were women. At 1 year, 36% of the patients reported having at least one type of sleep problem, after 3 years, this figure was 29%. Over 20% of the patients reported having “Rather big” or “Very big” problems with sleep after one year (Table 1) and 31% had problems at one or both time points (Table 2). Disturbed sleep was a problem for their health in 20% of the patients and 11% reported having “poor” or “very poor” sleep quality at both times. Insomnia was experienced by 118 (10%) patients at 1 year and 112 (11%) at 3 years.

Table 1.

Sleep problems at 1 and 3 years after diagnosis of RA.

1 year3 yearsInsomnia118 (9%)112 (11%)Not getting enough sleep102 (8%)113 (11%)Problems with sleep in general270 (22%)231 (22%)Sleep quality affecting health238 (19%)197 (19%)Poor sleep quality218 (17%)209 (20%)Problem with non-restorative sleep218 (17%)154 (14%)Table 2.

Individuals experiencing no problems, developing problems, improving or always having problems with their sleep at 1 and 3 years after diagnosis of RA.

No problems at any time pointImprovedDeveloped problemsProblems at both 1 and 3 yearsInsomnia702 (85%)43 (5%)46 (6%)39 (5%)Not getting enough sleep719 (86%)36 (4%)47 (6%)34 (4%)Problems with sleep in general576 (69%)81 (10%)78 (9%)103 (12%)Sleep quality affecting health616 (74%)65 (8%)70 (8%)85 (10%)Poor sleep quality623 (74%)57 (7%)66 (8%)91 (11%)Problem with non-restorative sleep654 (78%)71 (8%)46 (5%)67 (8%)

Conclusion:

In a population-based early RA cohort receiving today’s standard care, 30% of the patients reported some type of sleep problem during the first 3 years. Although this is a lower rate than has been reported in established RA, this is a significant proportion of RA patients, and these findings warrant further studies to closer identify the course of sleep problems and the factors influencing it such as pain.

References:

[1]Bourguignon C et al PMID 14596374

[2]Akerstedt T et al PMID 18484368

Acknowledgments:

The authors wish to acknowledge the EIRA study group and the EIRA data collectors.

Disclosure of Interests:

Tiina Lehtonen: None declared, Torbjörn Åkerstedr: None declared, Lauren Lyne: None declared, Lars Klareskog: None declared, Saedis Saevarsdottir Employee of: Part-time at deCODE Genetics/Amgen Inc, working on genetic research unrelated to this project, Lars Alfredsson: None declared, Helga Westerlind: None declared

The importance of differences; On environment and its interactions with genes and immunity in the causation of rheumatoid arthritis

The current review uses rheumatoid arthritis (RA) as a prominent example for how studies on the interplay between environmental and genetic factors in defined subsets of a disease can be used to formulate aetiological hypotheses that subsequently can be tested for causality using molecular and functional studies. Major discussed findings are that exposures to airways from many different noxious agents including cigarette smoke, silica dust and more interact with major susceptibility genes, mainly HLA-DR genetic variants in triggering antigen-specific immune reactions specific for RA. We also discuss how several other environmental and lifestyle factors, including microbial, neural and metabolic factors, can influence risk for RA in ways that are different in different subsets of RA.The description of these processes in RA provides the best example so far in any immune-mediated disease of how triggering of immunity at one anatomical site in the context of known environmental and genetic factors subsequently can lead to symptoms that precede the classical inflammatory disease symptoms and later contribute also to the classical RA joint inflammation. The findings referred to in the review have led to a change of paradigms for very early therapy and prevention of RA and to efforts towards what we have named 'personalized prevention'. We believe that the progress described here for RA will be of relevance for research and practice also in other immune-mediated diseases.

Breastfeeding is associated with reduced risk of multiple sclerosis in males, predominantly among HLA-DRB1*15:01 carriers

BACKGROUND

Breastfeeding as an infant appears protective against later development of some autoimmune diseases, but research into its influence on multiple sclerosis (MS) risk has yielded inconclusive results.

OBJECTIVE

We investigated the possible impact of breastfeeding on MS risk.

METHODS

We used two population-based case-control studies comprising 3670 cases and 6737 matched controls. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for association between MS and exposure to prolonged breastfeeding (4 months or longer) versus reduced breastfeeding (less than 4 months). A meta-analysis of case-control studies that assessed the impact of breastfeeding on MS risk among women and men was conducted.

RESULTS

Prolonged breastfeeding was associated with reduced MS risk among men (OR 0.7, 95% CI 0.5-0.9) but not among women (OR 0.9, 95% CI 0.8-1.1). Among men, a synergistic effect was observed between HLA-DRB1*15:01 carrier status and reduced breastfeeding.

CONCLUSIONS

Findings from the current study add to accumulating evidence that breastfeeding may be a modifiable protective factor for reducing the risk of MS in offspring. When possible, mothers should be supported to breastfeed their infants; however, the mechanism of a sex-specific biologic effect of breastfeeding on MS risk is unclear.

Family history of type 1 and type 2 diabetes and risk of latent autoimmune diabetes in adults (LADA)

BACKGROUND

A family history of diabetes (FHD) is a strong predictor of diabetes risk, yet has rarely been investigated in latent autoimmune diabetes in adults (LADA). This study therefore investigated the risk of LADA and type 2 diabetes (T2D) in relation to FHD, taking into account the type of diabetes in relatives.

METHODS

Data from a population-based study were used, including incident cases of LADA [glutamic acid decarboxylase antibody (GADA)-positive, n=378] and T2D (GADA-negative, n=1199), and their matched controls (n=1484). First-degree relatives with disease onset at age<40 years and taking insulin treatment were classified as type 1 diabetes (T1D) or, if otherwise, as T2D. Odds ratios (ORs) were adjusted for age, gender, BMI, education and smoking. Cases were genotyped for high- and low-risk HLA genotypes.

RESULTS

Both FHD-T1D (OR: 5.8; 95% CI: 3.2-10.3) and FHD-T2D (OR: 1.9; 95% CI: 1.5-2.5) were associated with an increased risk of LADA, whereas the risk of T2D was associated with FHD-T2D (OR: 2.7; 95% CI: 2.2-3.3), but not FHD-T1D. In LADA patients, FHD-T1D vs FHD-T2D was associated with higher GADA but lower C-peptide levels, lower prevalence of low-risk HLA genotypes (5.0% vs 28.6%, respectively; P=0.038) and a tendency for higher prevalence of high-risk genotypes (90.0% vs 69.1%, respectively; P=0.0576).

CONCLUSION

The risk of LADA is substantially increased with FHD-T1D but also, albeit significantly less so, with FHD-T2D. This supports the idea of LADA as a mix of both T1D and T2D, but suggests that the genes related to T1D have greater impact. LADA patients with FHD-T1D had more T1D-like features, emphasizing the heterogeneity of LADA.

Job strain as a risk factor for clinical depression: systematic review and meta-analysis with additional individual participant data

BACKGROUND

Adverse psychosocial working environments characterized by job strain (the combination of high demands and low control at work) are associated with an increased risk of depressive symptoms among employees, but evidence on clinically diagnosed depression is scarce. We examined job strain as a risk factor for clinical depression.

METHOD

We identified published cohort studies from a systematic literature search in PubMed and PsycNET and obtained 14 cohort studies with unpublished individual-level data from the Individual-Participant-Data Meta-analysis in Working Populations (IPD-Work) Consortium. Summary estimates of the association were obtained using random-effects models. Individual-level data analyses were based on a pre-published study protocol.

RESULTS

We included six published studies with a total of 27 461 individuals and 914 incident cases of clinical depression. From unpublished datasets we included 120 221 individuals and 982 first episodes of hospital-treated clinical depression. Job strain was associated with an increased risk of clinical depression in both published [relative risk (RR) = 1.77, 95% confidence interval (CI) 1.47-2.13] and unpublished datasets (RR = 1.27, 95% CI 1.04-1.55). Further individual participant analyses showed a similar association across sociodemographic subgroups and after excluding individuals with baseline somatic disease. The association was unchanged when excluding individuals with baseline depressive symptoms (RR = 1.25, 95% CI 0.94-1.65), but attenuated on adjustment for a continuous depressive symptoms score (RR = 1.03, 95% CI 0.81-1.32).

CONCLUSIONS

Job strain may precipitate clinical depression among employees. Future intervention studies should test whether job strain is a modifiable risk factor for depression.

VAV1 regulates experimental autoimmune arthritis and is associated with anti-CCP negative rheumatoid arthritis

Rheumatoid arthritis (RA) patients can be stratified into two subgroups defined by the presence or absence of antibodies against citrullinated circular peptides (anti-CCP) with most of the genetic association found in anti-CCP positive RA. Here we addressed the role of VAV1, previously associated to multiple sclerosis (MS), in the pathogenesis of RA in experimental models and in a genetic association study. Experimental arthritis triggered by pristane or collagen type II was induced in DA rats and in the DA.BN-R25 congenic line that carries a polymorphism in Vav1. Difference in arthritis severity was observed only after immunization with pristane. In a case-control study, 34 SNPs from VAV1 locus were analyzed by Immunochip genotyping in 11475 RA patients (7573 anti-CCP positive and 3902 negative) and 15,870 controls in six cohorts of European Caucasians. A combination of the previous MS-associated haplotype and two additional SNPs was associated with anti-CCP negative RA (alleles G-G-A-A of rs682626-rs2546133-rs2617822-rs12979659, OR=1.13, P=1.27 × 10^-5). The same markers also contributed to activity of RA at baseline with the strongest association in the anti-CCP negative group for the rs682626-rs12979659 G-A haplotype (β=-0.283, P=0.0048). Our study suggests a role for VAV1 and T-cell signaling in the pathology of anti-CCP-negative RA.

High consumption of coffee is associated with decreased multiple sclerosis risk; results from two independent studies

OBJECTIVE

Previous studies on consumption of caffeine and risk of multiple sclerosis (MS) have yielded inconclusive results. We aimed to investigate whether consumption of coffee is associated with risk of MS.

METHODS

Using two population-representative case-control studies (a Swedish study comprising 1620 cases and 2788 controls, and a US study comprising 1159 cases and 1172 controls), participants with different habits of coffee consumption based on retrospective data collection were compared regarding risk of MS, by calculating ORs with 95% CIs. Logistic regression models were adjusted for a broad range of potential confounding factors.

RESULTS

Compared with those who reported no coffee consumption, the risk of MS was substantially reduced among those who reported a high consumption of coffee exceeding 900 mL daily (OR 0.70 (95% CI 0.49 to 0.99) in the Swedish study, and OR 0.69 (95% CI 0.50 to 0.96) in the US study). Lower odds of MS with increasing consumption of coffee were observed, regardless of whether coffee consumption at disease onset or 5 or 10 years prior to disease onset was considered.

CONCLUSIONS

In accordance with studies in animal models of MS, high consumption of coffee may decrease the risk of developing MS. Caffeine, one component of coffee, has neuroprotective properties, and has been shown to suppress the production of proinflammatory cytokines, which may be mechanisms underlying the observed association. However, further investigations are needed to determine whether exposure to caffeine underlies the observed association and, if so, to evaluate its mechanisms of action.

Smoking is a major preventable risk factor for multiple sclerosis

BACKGROUND

Both smoking and exposure to passive smoking have repeatedly been associated with increased multiple sclerosis (MS) risk, but have never before been studied together. We assessed the public health impact of these factors.

METHODS

In a Swedish population-based case-control study (2455 cases, 5336 controls), we calculated odds ratios of developing MS associated with different categories of tobacco smoke exposure, together with 95% confidence intervals, by using logistic regression. The excess proportion of cases attributable to smoking and passive smoking was calculated as a percentage.

RESULTS

Both smoking and exposure to passive smoking contribute to MS risk in a dose-dependent manner. At the population level, 20.4% of all cases were attributable to smoke exposure. Among subjects carrying the genetic risk factor HLA-DRB1*15 but lacking HLA-A*02, 41% of the MS cases were attributable to smoking.

CONCLUSIONS

From a public health perspective, the impact of smoking and passive smoking on MS risk is considerable. Preventive measures in order to reduce tobacco smoke exposure are, therefore, essential. In particular, individuals with a history of MS in the family should be informed regarding the impact of smoking on the risk of MS, and the importance of preventing their children from being exposed to passive smoke.

Body mass index during adolescence, rather than childhood, is critical in determining MS risk

OBJECTIVE

Obesity in childhood and during adolescence has repeatedly been associated with increased risk of developing multiple sclerosis (MS). We aimed to investigate whether the most critical period occurs during childhood or later, during adolescence.

METHODS

Using a population-based case-control study (1586 cases and 2800 controls), individuals with different body sizes at age 10 and different body mass indices at age 20 were compared regarding MS risk, by calculating odds ratios with 95% confidence intervals. Potential interactions between HLA-DRB1*15 and absence of HLA-A*02, respectively, and both childhood and adolescent obesity were evaluated by calculating the attributable proportion due to interaction.

RESULTS

Regardless of body size at age 10, individuals with adolescent obesity had a 90% increased risk of MS. Among participants who were not obese at age 20, no association was observed between body size at age 10 and subsequent MS risk. An interaction was observed between the HLA MS risk genes and adolescent, but not childhood, obesity.

CONCLUSIONS

Our results suggest that BMI during adolescence, rather than childhood, is critical in determining MS risk.

Comparative analysis of first-year fingolimod and natalizumab drug discontinuation among Swedish patients with multiple sclerosis

BACKGROUND

Natalizumab (NTZ) and fingolimod (FGL) are mainly used second line in relapsing-remitting multiple sclerosis (MS), although pivotal trials included mainly treatment-naïve patients.

OBJECTIVE

This study aims to provide real-world data on safety and discontinuation rates.

METHODS

Using IMSE, a drug monitoring registry for all newer MS drugs in Sweden, we analysed differences in baseline characteristics and 1-year drug survival for patients registered 2011-2013, initiating treatment with NTZ (n=640) or FGL (n=876). Among FGL initiators, n=383 (44%) had previously used NTZ (FGL(afterNTZ)).

RESULTS

Compared with NTZ, the FGL cohort was older and more often male (36/38 years, 24%/33% males). Baseline Expanded Disability Status Scale was similar across groups, but MS Severity Score was higher in NTZ patients, and Symbol Digit Modalities Test and MS Impact Scale (MSIS-29) was higher in FGL(afterNTZ) versus FGL(NTZ-naïve) patients. Proportion on drug after 1 year was high, NTZ=87%, FGL(NTZ-naïve)=83% and FGL(afterNTZ)=76%. Adverse events was the most frequent reason for discontinuing FGL (FGL(NTZ-naïve)=9%, FGL(afterNTZ)=12%), and was significantly higher than on NTZ (3%). In contrast, the proportion of patients stopping treatment due to lack of effect was more similar: NTZ=4%, FGL(NTZ-naïve)=3%, FGL(afterNTZ)=8%.

CONCLUSION

FGL and NTZ were both well tolerated, but FGL less so than NTZ, especially in patients switching to FGL from NTZ. Group differences were not explained by differences in recorded baseline characteristics.

Shift work influences multiple sclerosis risk

BACKGROUND

An association between working shift at a young age and subsequent risk for multiple sclerosis (MS) has been observed.

OBJECTIVE

To investigate whether this finding could be replicated, and to further explore the influence of age at first exposure to shift work.

METHODS

Using a Swedish population-based, case-control study (2337 cases and 4904 controls), the incidence of MS among subjects whom had worked shifts was compared with that of those whom had not, by calculating odds ratios (ORs) with 95% confidence intervals (CIs) by means of logistic regression.

RESULTS

The OR of developing MS was 1.5 (95% CI 1.2-1.8) among those whom started working shifts before age 20, whereas a less pronounced association was observed among those whom started working shifts at age 20 or later (OR 1.2; 95% CI 1.1-1.4). The effect of shift work was more pronounced among subjects whom had been exposed at a young age, regardless of the duration between the start of shift work and disease onset.

CONCLUSION

Some aspects of adolescence seem to be of great importance, regarding the impact of shift work on MS risk. Circadian disruption and sleep deprivation may contribute towards explaining the association; however, the exact mechanisms behind our observations remain to be elucidated.

Obesity interacts with infectious mononucleosis in risk of multiple sclerosis

BACKGROUND AND PURPOSE

The possible interaction between adolescent obesity and past infectious mononucleosis (IM) was investigated with regard to multiple sclerosis (MS) risk.

METHODS

This report is based on two population-based case-control studies, one with incident cases (1780 cases, 3885 controls) and one with prevalent cases (4502 cases, 4039 controls). Subjects were categorized based on adolescent body mass index (BMI) and past IM and compared with regard to occurrence of MS by calculating odds ratios with 95% confidence intervals (CIs) employing logistic regression. A potential interaction between adolescent BMI and past IM was evaluated by calculating the attributable proportion due to interaction.

RESULTS

Regardless of human leukocyte antigen (HLA) status, a substantial interaction was observed between adolescent obesity and past IM with regard to MS risk. The interaction was most evident when IM after the age of 10 was considered (attributable proportion due to interaction 0.8, 95% CI 0.6-1.0 in the incident study, and attributable proportion due to interaction 0.7, 95% CI 0.5-1.0 in the prevalent study). In the incident study, the odds ratio of MS was 14.7 (95% CI 5.9-36.6) amongst subjects with adolescent obesity and past IM after the age of 10, compared with subjects with none of these exposures. The corresponding odds ratio in the prevalent study was 13.2 (95% CI 5.2-33.6).

CONCLUSIONS

An obese state both impacts the cellular immune response to infections and induces a state of chronic immune-mediated inflammation which may contribute to explain our finding of an interaction between adolescent BMI and past IM. Measures taken against adolescent obesity may thus be a preventive strategy against MS.

A genome-wide association study of anorexia nervosa

Anorexia nervosa (AN) is a complex and heritable eating disorder characterized by dangerously low body weight. Neither candidate gene studies nor an initial genome-wide association study (GWAS) have yielded significant and replicated results. We performed a GWAS in 2907 cases with AN from 14 countries (15 sites) and 14 860 ancestrally matched controls as part of the Genetic Consortium for AN (GCAN) and the Wellcome Trust Case Control Consortium 3 (WTCCC3). Individual association analyses were conducted in each stratum and meta-analyzed across all 15 discovery data sets. Seventy-six (72 independent) single nucleotide polymorphisms were taken forward for in silico (two data sets) or de novo (13 data sets) replication genotyping in 2677 independent AN cases and 8629 European ancestry controls along with 458 AN cases and 421 controls from Japan. The final global meta-analysis across discovery and replication data sets comprised 5551 AN cases and 21 080 controls. AN subtype analyses (1606 AN restricting; 1445 AN binge-purge) were performed. No findings reached genome-wide significance. Two intronic variants were suggestively associated: rs9839776 (P=3.01 × 10(-7)) in SOX2OT and rs17030795 (P=5.84 × 10(-6)) in PPP3CA. Two additional signals were specific to Europeans: rs1523921 (P=5.76 × 10(-)(6)) between CUL3 and FAM124B and rs1886797 (P=8.05 × 10(-)(6)) near SPATA13. Comparing discovery with replication results, 76% of the effects were in the same direction, an observation highly unlikely to be due to chance (P=4 × 10(-6)), strongly suggesting that true findings exist but our sample, the largest yet reported, was underpowered for their detection. The accrual of large genotyped AN case-control samples should be an immediate priority for the field.

Snus (Swedish smokeless tobacco) use and risk of stroke: pooled analyses of incidence and survival

BACKGROUND

Snus is a moist smokeless tobacco product with high nicotine content. Its use has a short-term effect on the cardiovascular system, but the relationship between snus use and stroke is unclear.

OBJECTIVE

The aim of this study was to assess the associations between use of snus and incidence of and survival after stroke, both overall and according to subtypes.

METHODS

Pooled analyses of eight Swedish prospective cohort studies were conducted, including 130 485 men who never smoked. We estimated hazard ratios (HRs) with 95% confidence intervals (CIs) of incidence and death after diagnosis using Cox proportional hazard regression models and case fatality and survival using logistic regression and Kaplan-Meier methods, respectively.

RESULTS

No associations were observed between the use of snus and the risk of overall stroke (HR 1.04, 95% CI 0.92-1.17) or of any of the stroke subtypes. The odds ratio (OR) of 28-day case fatality was 1.42 (95% CI 0.99-2.04) amongst users of snus who had experienced a stroke, and the HR of death during the follow-up period was 1.32 (95% CI 1.08-1.61).

CONCLUSION

Use of snus was not associated with the risk of stroke. Hence, nicotine is unlikely to contribute importantly to the pathophysiology of stroke. However, case fatality was increased in snus users, compared with nonusers, but further studies are needed to determine any possible causal mechanisms.

Job strain and the risk of severe asthma exacerbations: a meta-analysis of individual-participant data from 100 000 European men and women

Background

Many patients and healthcare professionals believe that work‐related psychosocial stress, such as job strain, can make asthma worse, but this is not corroborated by empirical evidence. We investigated the associations between job strain and the incidence of severe asthma exacerbations in working‐age European men and women.

Methods

We analysed individual‐level data, collected between 1985 and 2010, from 102 175 working‐age men and women in 11 prospective European studies. Job strain (a combination of high demands and low control at work) was self‐reported at baseline. Incident severe asthma exacerbations were ascertained from national hospitalization and death registries. Associations between job strain and asthma exacerbations were modelled using Cox regression and the study‐specific findings combined using random‐effects meta‐analyses.

Results

During a median follow‐up of 10 years, 1 109 individuals experienced a severe asthma exacerbation (430 with asthma as the primary diagnostic code). In the age‐ and sex‐adjusted analyses, job strain was associated with an increased risk of severe asthma exacerbations defined using the primary diagnostic code (hazard ratio, HR: 1.27, 95% confidence interval, CI: 1.00, 1.61). This association attenuated towards the null after adjustment for potential confounders (HR: 1.22, 95% CI: 0.96, 1.55). No association was observed in the analyses with asthma defined using any diagnostic code (HR: 1.01, 95% CI: 0.86, 1.19).

Conclusions

Our findings suggest that job strain is probably not an important risk factor for severe asthma exacerbations leading to hospitalization or death.