[An analysis of latent tuberculosis infection among patients with rheumatic diseases]

To investigate the incidence of latent tuberculosis infection (LTBI) in patients with rheumatic diseases in order to find evidence for the prevention of mycobacterium tuberculosis (MTB) in these patients.

From January 2013 to July 2015, 759 patients with rheumatic diseases and 38 health controls were enrolled. All of them underwent interferon-gamma release assays(T-SPOT.TB)to screen for LTBI. Incidence of MTB infection was evaluated in different groups and test was used for statistical analysis between groups.

The incidences of LTBI in patients and health controls were 27.27%(207/759) and 10.53%(4/38), respectively. In 2013, 24.66%(73/296) (standardized infection rate 23.37%) patients with rheumatic diseases were positive for LTBI screening test. In 2014 and 2015, the percentages were 32.02%(73/296) (standardized infection rate was 32.15%) and 25.96%(73/228) (standardized infection rate was 28.46%), respectively, which was statistically significant in these 3 groups (P=0.004). the infection rate in 2014 tended to be higher than that in 2013 (P=0.001). There were 30.24%(88/291) male and 25.43%(119/468)female patients who were considered as LTBI. But the difference was not significant between genders. The infection rates between patients older than 60 years old and less was significantly different, which were 45.65%(42/92) and 24.74%(165/667), respectively (P=0.000). As far as diseases were concerned including rheumatoid arthritis, systemic lupus erythematosus, spondyloarthritis and other rheumatic diseases, the incidences were 33.93%(57/168), 22.06%(45/204), 25.73%(44/171) and 28.24%(61/216) respectively, without statistical significance.

The incidence of LTBI is high in patients with rheumatic diseases. Attention should be paid especially to elderly patients and rheumatoid arthritis patients who have relatively higher rates of LTBI. Careful monitoring and prevention measures are suggested to take in these patients.