Objectives: To investigate the association between rheumatoid arthritis (RA) and urbanization and compare the medication selection for RA patients in urban vs. rural areas.
Methods: RA patients were identified among 1,000,000 random individuals from a 23-million-person nationwide health insurance database, and controls were matched at a 1 : 10 ratio. Taiwan's 359 townships were grouped into 7 urbanization levels. Geographic region and monthly income were also analyzed. Medication use in the most urbanized and less-urbanized areas were also compared.
Results: Rural dwellers had lower odds of having an RA diagnosis. The odds ratio (OR) for level 5 area residents of having an RA diagnosis was 0.62 (95% confidence interval (CI) 0.46 - 0.85; p = 0.002), and they were both 0.76 for level 6 - 7 area residents (95% CI, 0.61 - 0.95 for level 6; p = 0.017 and 0.60 - 0.96 for level 7; p = 0.021) compared to level 1 (the most urban dwellers). The ORs of having a new RA diagnosis were 0.57 (95% CI 0.41 - 0.79, p = 0.001) in eastern Taiwan and 0.33 (95% CI 0.15 - 0.69, p = 0.004) on offshore islands compared to northern Taiwan. No association was found between monthly income and RA. Urban-dwelling RA patients used more tumor necrosis factor-α antagonists (level 1 urbanization; n = 24; 2.3%) than RA patients in less-urbanized areas (level 2 - 7 urbanization n = 30; 1.3%; p = 0.038).
Conclusion: Results of this study suggested that an RA diagnosis and treatment are associated with urbanization.