Screening Optimization of Latent Tuberculosis Infection in Rheumatoid Arthritis Patients

Prevalence of Latent Tuberculosis Infection (LTBI) in Mexican Patients With Rheumatoid Arthritis (RA)

INTRODUCTION

Patients with rheumatoid arthritis (RA) are at increased risk of developing tuberculosis, and even more so if they receive biological agents. In Mexico, the prevalence of latent tuberculosis infection (LTBI) in RA diagnosed by interferon-gamma release assay (IGRA) is largely unknown. The objective was to determine LTBI prevalence and the associated risk factors in rheumatoid arthritis patients.

METHODS

A cross-sectional study was performed comprising 82 patients with RA who attended the rheumatology service at a second-level hospital. Demographic characteristics, comorbidity, Bacillus Calmette-Guerin (BCG) vaccination and smoking history, type of treatment, disease activity and functional capacity were investigated. The Disease Activity Score 28 and the Health Assessment Questionnaire-Disability Index were applied for the estimate of RA activity and functional capacity. Further information was compiled from the electronic medical records and personal interviews. LTBI was determined by QuantiFERON TB Gold Plus (QIAGEN, Germantown, USA).

RESULTS

Prevalence of LTBI was 14% (95% confidence interval (CI): 8.6% to 23.9%). Factors associated with LTBI were history of smoking (odds ratio (OR) = 6.63 95% CI 1.01 to 43.3) and disability score (OR = 7.19 95%CI 1.41 to 36.6).

CONCLUSIONS

The prevalence of LTBI in Mexican patients with RA was 14%. Our results suggest prevention of smoking and functional incapacity could reduce the risk of LTBI. Further research could endorse our results.

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.

Association of Body Mass Index with the Tuberculosis Infection: a Population-based Study among 17796 Adults in Rural China

Body mass index (BMI) has been shown to be associated with host susceptibility to several infections. However, the link between BMI and the risk of tuberculosis (TB) infection has been sparsely studied in China and in worldwide. Based on the baseline survey of a population-based, prospective study in rural China, the association between BMI and TB infection among adults was estimated by means of cross-sectional analysis. TB infection status was tested using QuantiFERON-TB Gold In-Tube (QFT), a commercial of interferon-γ release assay (IGRA). Totally, 17796 eligible participants aged ≥18 years from 4 study sites, were included in the analysis. 21.76% (3873/17796) were observed to be QFT positive. Age and gender standardized prevalence ranged from 16.49% to 23.81% across the study sites. 42.19% study participants were obese/overweight with BMI ≥ 24.0 kg/m². BMI ≥ 28.0 kg/m² was observed to be independently associated with QFT positivity (adjusted odds ratio: 1.17, 95% confidence interval: 1.04–1.33). The strength of the association was found to be geographically diversity, which might be explained, at least partly, by the varied local TB epidemic status. Our results suggest that individuals with obesity might be one important target population for TB infection control in rural China.