A retrospective study on the risk of tuberculosis in patients with rheumatoid arthritis.

Tuberculosis (TB) is an important preventable infection in patients with rheumatoid arthritis (RA). To determine the risk of TB in patients with RA by comparing with those with non-specific back pain (NSBP), and to identify the risk factors in the RA group. Medical data were retrieved from a centralized electronic database. A total of 1099 patients with RA and 2489 patients with NSBP were identified. Clinical data, comorbidities, and use of individual disease-modifying anti-rheumatic drugs (DMARDs) were retrieved. Risks of TB in patients with RA and NSBP were compared by propensity score (PS) adjusted analysis with known or potential risk factors for TB. Risk factors of TB were also determined in patients with RA. There were 14 cases of TB in RA group and 25 cases in NSBP group. Median duration of follow-up were 11.3 (0.1-21.9) years in RA group and 15.4 (0.1-24.4) years in NSBP group. The risk of TB in patients with RA was 2.53 times higher (HR 2.53; 95% CI 1.29, 4.94; p < 0.01) than in patients with NSBP. After excluding patients on DMARDs, the risk became similar (HR 2.72; 95% CI 0.81, 9.14; p = 0.11). Independent risk factors found were etanercept (HR 7.16; 95% CI 1.41, 36.30; p = 0.02), and previous TB infection (HR 25.23; 95% CI 6.99, 91.09; p < 0.001). The risk of extrapulmonary involvement between RA and NSBP groups was similar (HR 1.21; 95% CI 0.22, 6.57; p = 0.83). The risk of TB was increased in patients with RA. Anti-TNF therapy was an identified risk factor.