Positive Rates Of Tuberculin Skin Test Research Articles

The prevalence of latent tuberculosis infection in patients with inflammatory arthritis and the diagnostic efficacy of different screening methods

Objective: To investigate the prevalence of latent tuberculosis infection (LTBI) in patients with inflammatory arthritis, and to compare the efficacy of tuberculin skin test (TST) and QuantiFERON-TB Gold (QFT) in screening for LTBI in these patients. Method: Medical records of 149 patients with inflammatory arthritis admitted to inpatient of Peking University International Hospital from December 2015 to December 2017 (diagnosis with rheumatoid arthritis, ankylosing spondylitis, sero-negative spondyloarthropathy, psoriatic arthritis, or reactive arthritis) who accepted TST or QFT were collected. The information included gender, age, history of tuberculosis infection, calcifications presence in chest X-ray or chest CT, TST result, QFT result, medication history before test, and biological treatment and all the patients were made a follow-up. Results: The positive rate of TST was 18.2%(14/77) and that of QFT was 27.1%(26/96), and the overall consistency between the two tests was fair. The rate of LTBI diagnosed by QFT was 22.9%(22/96). The positive rate of TST in patients older than 50 years was significantly higher than those younger than 50 years, but there was no significant difference between the two groups screened by QFT. The M-N values in QFT were decreased in both the patients above the age of 50 and in the patients using immunosuppressive agents. A total of 64 patients accepted biological agent therapy, and in those with a positive result of TST or QFT, only 2 cases received anti-LTBI treatment, but the other 14 cases without anti-LTBI treatment. None of them developed active tuberculosis in the following 3-24 months. Conclusion: The prevalence of LTBI in patients with inflammatory arthritis is consistent with that reported in rheumatoid patients, which is higher than in general people. In patients with inflammatory arthritis older than 50 years, especially those accepted immunosuppressive agents therapy, the immunity may be impaired and QFT is more sensitive than TST for screening LTBI.

The prevalence of latent tuberculosis infection among Iranian sarcoidosis patients

Background: Sarcoidosis is a multisystemic disorder with unknown causes. Mycobacterium tuberculosis has been implicated as one of the possible causes of sarcoidosis. Interferon-gamma release assays are in vitro diagnostic tests for detection of the latent tuberculosis infection (LTBI) which has been replaced by tuberculin skin test (TST) in some countries. The purpose of this study was to investigate the prevalence of LTBI in Iranian sarcoidosis patients. Methods: Ninety participants with the mean age of 42.22 ± 14.55 were enrolled in this study. They were divided into three equal groups consisted of patients with active TB, patients with sarcoidosis, and controls. TST and QuantiFERON®-TB Gold (QFT) were performed according to the manufacturer's instructions and the result interpreted. Results: The positive rates of TST were 76.66%, 3.3%, and 6.66% in TB, sarcoidosis, and control groups, respectively. However, QFT was positive in 24 (96.66%) of the TB group, 6 (20%) of sarcoidosis patients, and 5 (16.66%) of the control group. The agreement between the aforementioned tests was low (Cohen's kappa coefficient (κ) = 0.24). Conclusions: The current study suggests that in an intermediate-incidence TB population such as Iran, QFT is much more accurate than TST for the diagnosis of LTBI in patients with sarcoidosis. The present finding increases the possibility of this hypothesis which states that nontuberculous mycobacteria may play a role in the etiology of sarcoidosis.

A Pulmonary Tuberculosis Cluster in an Institution in Southern Taiwan, 2012

A mental institution resident in Southern Taiwan was ill and sought medical service in March 2014; later was confirmed as pulmonary tuberculosis (TB). Two contacts were found having abnormal chest radiography at the twelfth month and were notified. In July 2013, there were six reported probable patients with pulmonary tuberculosis from the institution including the index case. Five of them were confirmed, and one was excluded. Restriction fragment length polymorphism (RFLP) molecular study done at the Research and Diagnostic Center of Taiwan CDC revealed that the five isolates belonged to the same subtype, thus, proved this cluster of patients with pulmonary tuberculosis. After two serial meetings with TB specialists, not only chest radiographies of related contacts were followed, but also extended the immunoassay from the previous existing tuberculin skin test (TST) to both interferon-gamma release assay (IGRA; QuantiFERON-TB, QFT) and TST for those identified contacts. After evaluation by physicians, the contacts who had both positive results of TST and IGRA were undergone latent tuberculosis infection (LTBI) treatment. Besides, we suggested the administrator keeping the confirmed TB patients in the isolation room on the first floor until his/her sputum was negative for acid-fast stain or TB culture, and also to isolate those suspected TB patients.Of total 85 contacted people, the positive rate of TST was 77.6% (66/85), the positive rate of QFT was 29.5% (18/61), and the positive rate for both TST and QFT was 21.2% (18/85). Twenty-four people underwent LTBI treatment, of whom 22 people completed the treatment course, and 2 people discontinued due to the adverse effects. There was not any tuberculosis patient found in the institution by October 2014.

Screening of latent tuberculosis infection by interferon-γ release assays in rheumatic patients: a systemic review and meta-analysis.

The aim of this study is to assess the diagnostic value of interferon-γ release assays (IGRAs) for latent tuberculosis infection (LTBI) in patients with rheumatic disease before receiving biologic agents. MEDLINE and EMBASE databases were used for searching studies concerning the evaluation on the performance of IGRAs [QuantiFERON-TB Gold (QFT-G), QuantiFERON-TB Gold In-Tube (QFT-GIT) and T-SPOT.TB] in rheumatic patients before biological therapy. After assessing the quality of all studies included in the review, we summarized the results in subgroups using forest plots and calculated pooled estimates if applicable. The search identified 11 studies with a total sample size of 1940 individuals. Compared with the tuberculin skin test (TST), the pooled agreements in QFT-G/GIT and T-SPOT.TB were 72 % (95 % confidence interval (CI) 65, 78 %) and 75 % (95 % CI 67, 83 %), respectively. BCG vaccination was positively correlated with positive rates of TST (pooled odds ratio (OR) 1.64, 95 % CI 1.06, 2.53). Compared with TST, IGRAs were better associated with the presentence of one or more tuberculosis (TB) risk factors. Neither steroid nor disease-modifying anti-rheumatic drugs (DMARDs) significantly affect positive IGRA results. In contrast, TST positivity was significantly impacted by the use of steroid (pooled OR 0.45, 95 % CI 0.30, 0.69), but less significantly by the use of DMARDs (pooled OR 0.78, 95 % CI 0.50, 1.21). In conclusion, in rheumatic patients with previous BCG vaccination or currently on steroid therapy, IGRAs would be the better choice to identify LTBI by decreasing the false-positivity and false-negativity rate compared with conventional TST.

Tuberculin reaction is not attenuated in patients with rheumatoid arthritis living in a region with intermediate burden of tuberculosis

Tuberculin reactions in patients with immunocompromised conditions have been reported to be attenuated compared with healthy controls. In the case of rheumatoid arthritis (RA), several studies have reported conflicting results. We performed this study to evaluate the tuberculin reaction in patients with RA in a region with intermediate burden of tuberculosis. Eighty-one RA patients and 104 age- and sex-matched controls who underwent tuberculin skin test (TST) at Severance Hospital in Seoul, South Korea were reviewed. TST was carried out using the Mantoux method. Indurations larger than 10 mm were considered positive. Information about risk factors for latent tuberculosis infection was acquired. The mean age of the patients with RA was 48 ± 14 years, and the median disease duration was 9 (1-203) months. The mean DAS28 was 5.22 ± 0.13. The control group consisted of healthy living donors for liver transplantation and the patients with diseases not related with immunosuppression. BCG vaccination, close contact history with active tuberculosis, and history of pulmonary tuberculosis were not different between the two groups. The positive rate of TST (34.6% vs. 38.5%) and the median skin induration size (5 mm vs. 6 mm) of the two groups were similar. Medications and DAS28 were not associated with the TST result. The tuberculin reaction of patients with RA is not attenuated compared with that of controls in South Korea.

Clinical Significance of Interferon γ Release Assay for Diagnosis of Tuberculosis in Children

Purpose : The purpose of this study is to evaluate the usefulness and limitation of QuantiFERON-TB Gold (QTB) for diagnosis of latent tuberculosis in children. Methods : The medical records of 112 children who were tested by tuberculin skin test (TST) and QTB for detection of latent tuberculosis (TB) in Eulji General Hospital during the period from January 2007 to June 2009 were retrospectively reviewed. Results : Of the 112 participants, the clinical TB group included 15 (13.4%), the contact group included 43 (38.4%), and the non-contact group included 54 (48.2%). Positive rates of TST and QTB were 100% and 80% in the clinical TB group, 64% and 14% in the close contact group, 27% and 0% in the casual contact group, and 52% and 2% in the non-contact group, respectively. Sensitivity of QTB was 80.0% and specificity was 92.6%. Agreement between QTB and TST was poor (=0.209). We also confirmed that the positive rate of QTB increased as the age of the patient increased (P=0.011). A QTB indeterminate result was observed in 11 (9.8%) subjects. QTB was retested in 15 subjects. In 5 of the 6 subjects who had positive results initially, positive results persisted for a median 2.2 months after termination of treatment. Conclusion : Although QTB was associated with several problems, including low sensitivity and a high rate of indeterminate results, it had clinical importance due to its high specificity. We found good correlation with regard to exposure and QTB positivity, including that of young children under 5 years of age. However, clinical application of interferon- releasing assay for young children for diagnosis of active and latent tuberculosis will require additional prospective studies.