Background Smoking is the major known environmental risk factor for RA, and notably this risk factor is exclusively seen in ACPA-positive RA. Whether this increased risk is due to nicotine or other substances of inhaled tobacco smoke is unclear. Smokeless tobacco contains nicotine and is often used as an alternative to smoking. The role of smokeless tobaccoin the etiology of RA has to date only been reported from a Swedish study based on male construction workers, where no association was observed between the use of moist snuff and the risk of RA. However, whether smokeless tobacco is related to the ACPA-positive or ACPA-negative RA remains to be elucidated.
Objectives In this report we aimed at investigating the association between the use of moist snuff and the risk of RA, and if this exposure has different impact on ACPA-positive and ACPA-negative disease.
Methods Data from EIRA (Epidemiological Investigation of Rheumatoid Arthritis), a population-based case-control study from Sweden, was used. In total, information from1962 incident cases and 2247 randomly selected controls (matched on age, sex and residency), aged 18-70 years, was analysed. Ever, current and past moist snuff users were compared with never users. We calculated odds ratios (OR) with 95% confidence intervals (CI) for RA overall and the ACPA-positive and ACPA-negative subsets, by means of unconditional logistic regression models. All analyses were adjusted for age, sex, residency, pack-years of cigarette smoking and alcohol consumption.
Results In total, 254 (13%) cases were ever moist snuff users compared with 290 (13%) controls, resulting in an odds ratio of 1.0 (95% CI 0.8-1.2). When exposure to moist snuff was analysed in relation to the incidence of ACPA-positive and ACPA-negative disease, no associations were observed. Furthermore, neither current nor past moist snuff use was related to the risk of RA, or the two sub-groups of the disease.
Conclusions The use of moist snuff was not associated with RA risk, neither with regard to ACPA-positive nor ACPA-negative RA. The increased risk of RA associated with smoking may thus not be due to nicotine.
References Carlens C, et al: Smoking, Use of Moist Snuff, and risk of chronic inflammatory diseases. Am J Respir Crit Care Med. 2010;181:1217-22
Disclosure of Interest None Declared