Background Rheumatoid arthritis (RA) increased risk of Mycobacterium Tuberculosis Infection (TB). Risk of TB infection in RA patients from Thailand, the country with moderate prevalence of TB infection (137/100,000 in general population) has not been studied.
Objectives The aim of this study was to determine incidence and factors related TB infection in RA patients from Thailand.
Methods All patients were diagnosed with RA according to American College of Rheumatology (ACR) 1987 and/or ACR and European league of Rheumatology 2010 between 2000 and 2015. Twenty Cases of TB infection diagnosed after having RA were identified. TB infection was diagnosed by WHO 2013 revision definition and confirmed by physicians. Four age and sex matched controls were selected from 355 RA patients from Thai Army Rheumatoid Arthritis Cohort. Demographic data, RA disease associated factors and risk factos for TB infection were collected. Incidence rate was calculated by incidence density. Univariable and multivariable analyses were performed to identify factors associated with TB.
Results Twenty-nine TB cases and 116 controls were included and 85.60% were female. The mean age ± SD was 64.75±11.06 years and mean disease duration ± SD was 12.79±7.15 years. Rheumatoid factor and anti-citrullinated protein antibody were positive in 75.23 and 68.95%, respectively. Most patients (93.18%) were treated with synthetic DMARDs. The combination of biologic and synthetic DMARDs was used in 7.58% of the patients. Incidence of TB infection was 2,180/100,000 person-year. Cases were more likely to have higher disease activity, use higher dose of methotrexate, use higher dose of leflunomide and use higher dose of glucocorticoid than controls. The means ± SD of Disease activity28 score (DAS28), dose of methotrexate, dose of leflunomide and dose of glucocorticoid in cases and control were 5.26 ±1.73 vs 4.45 ±1.51 (p=0.027), 9.84 ±6.02 vs 6.47 ±5.62 mg/week (p=0.03), 15±9.26 vs 6.55±7.53 mg/day (p=0.06) and 6.17±5.18 vs 1.15±2.06 mg/day (p=0.005), respectively. In multivariate regression analysis, only high DAS28 and current use of prednisolone were independently associated with TB infection (Odd ratio, 95% CI of 4.95, 1.15–8.36 and 1.23, 1.04–1.44, respectively).
Conclusions Incidence of TB infection in RA in this study was very high compared to general population in Thailand and other Asian countries such as Hong Kong and Korea. High RA disease activity and the use of glucocorticoid are independently associated with TB infection.
Navarra S et al. International Journal of Rheumatic Diseases 2014; 17: 291–298.
Mok CC, et al. International Journal of Rheumatic Diseases 2014;17 Suppl 3:1–8.
Seong SS, et al. Kim EM, et al. J Rheumatol 2011;38:2218–2230.
Disclosure of Interest None declared