Objective: The objective of this medical record review study is to define the association between smoking and Sjӧgren's syndrome (SS) in a large rheumatoid arthritis (RA) cohort.
Methods: Electronic health records from a population-based cohort were screened for RA eligibility between 2005 and 2018. Inclusion criteria were age ≥ 18 years, two or more RA diagnoses, including two diagnoses by a rheumatologist, or positive rheumatoid factor or anti-cyclic citrullinated peptide (anti-CCP) antibody. The independent variable, smoking status, was defined as never, current, or past. The outcome, SS, was defined by two or more ICD-9 codes. Multivariable logistic regression was performed to determine odds ratios (ORs) of SS adjusted for age, sex, and race.
Results: Among 1861 patients with RA identified for cohort inclusion, 1296 had a reported smoking status. Current smokers were younger and less likely to be female than never smokers. The adjusted OR of current compared to never smokers was negatively associated with SS [OR 0.20, 95% confidence interval (CI) 0.06-0.65]. Female sex and age were associated with SS (OR 2.70, 95% CI 1.18-6.14; OR 3.75, 95% CI 1.23-11.4).
Conclusion: We report that RA patients who currently smoke had 80% lower odds of SS. Age had a 3.7-fold association and female sex a 2.7-fold association with SS among RA patients. Our data suggest a negative correlation between current smoking and prevalent SS among RA patients. Prospective studies examining pack-year relationships or smoking cessation could further examine risk reduction and causality to follow-up our cross-sectional observational study.