AB0054 IS TEA CONSUMPTION ASSOCIATED WITH RISK OF RHEUMATOID ARTHRITIS?

Abstract

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