Previous history of tuberculosis is associated with rheumatoid arthritis

Previous studies have suggested that mycobacterial infections could trigger autoimmune diseases, including rheumatoid arthritis (RA).To explore the association between previous tuberculosis (TB) and RA.We conducted a case-control study using data obtained from the National Health Insurance (NHI) system of Taiwan. We identified 26 535 adults with RA from 2002 to 2011, with the date of diagnosis as the index date. This number was randomly selected and frequency-matched four times by age, sex and the year of index date from among non-RA individuals. Odds ratios (ORs) of RA were calculated for associations with TB.Compared with controls, RA patients had a crude OR of 1.77 for TB (95%CI 1.61-1.94). The strength of the association between RA and TB remained at the same level after controlling for other potential risk factors (adjusted OR 1.73, 95%CI 1.57-1.90), although RA patients tended to have a higher prevalence of hypertension, coronary artery disease and kidney disease.TB was much more prevalent in RA patients than in control subjects. Prospective cohort studies are required to establish a causal relationship between previous TB and RA.