Effectiveness of Latent TB Screening and Treatment in People Initiating Dialysis in British Columbia, Canada

Tuberculosis screening practices and outcomes in an australian dialysis unit

BACKGROUND

The World Health Organisation (WHO) recommends all dialysis patients undertake routine screening for latent tuberculosis infection (LTBI) in high income countries such as Australia. However, we employ a targeted screening approach in our Australian dialysis unit in line with local and some international guidelines. We analysed our practices to assess the validity of our approach.

METHODS

A retrospective review of new dialysis patients during the period 2012-2018 was undertaken. Patient records were reviewed for basic demographic data, comorbidities, LTBI screening using Quantiferon Gold (QFG), and outcomes, including episodes of active TB, to June 2020.

RESULTS

472 patients were included. WHO high risk country of origin patients accounted for 22% (n = 103). 229 patients (48.5%) were screened using QFG. The single main indication for screening was transplantation waitlisting. 34 patients had a positive QFG result. Active tuberculosis developed in two patients during the observation period. Both occurred in the screened cohort, the cases having previously tested negative via QFG at 11 and 16 months, prior to the development of active tuberculosis. No patients in the unscreened cohort developed active tuberculosis during the observation period. WHO high risk country of origin was associated with positive QFG status, odds ratio 10.4 (95% CI 3.3-31.2).

CONCLUSION

The data failed to show a benefit from widening of the screening program within our dialysis unit. However, a much larger sample size will be required to confidently assess the impact of the current approach on patient outcomes. Analysis of current screening practices and outcomes across all Australian dialysis services is warranted to assess the risks and benefits of widening the screening practices to include all dialysis patients as recommended by the WHO.

Diagnosis of Latent Tuberculosis Infection in Hemodialysis Patients: TST versus T-SPOT.TB

Hemodialysis (HD) patients should be screened for latent tuberculosis (TB) infection. We aimed to determine the frequency of latent TB infection in HD patients and to compare the effectiveness of the tests used. The files of 56 HD patients followed between 1 January 2021 and 1 October 2022 were retrospectively analyzed. Demographic data, the presence of the Bacillus Calmette-Guerin (BCG) vaccine, whether or not the patients had previously received treatment for TB before, the status of encountering a patient with active TB of patients over 18 years of age, without active tuberculosis and who had a T-SPOT.TB test or a Tuberculin Skin Test (TST) were obtained from the patient files. The presence of previous TB in a posterior-anterior (PA) chest X-ray was obtained by evaluating PA chest X-rays taken routinely. Of the patients, 60.7% (n = 34) were male and their mean age was 60.18 ± 14.85 years. The mean duration of dialysis was 6.43 ± 6.03 years, and 76.8% (n = 43) had 2 BCG scars. The T-SPOT.TB test was positive in 32.1% (n = 18). Only 20 patients (35.7%) had a TST and all had negative results. While the mean age of those with positive T-SPOT.TB results was higher (p = 0.003), the time taken to enter HD was shorter (p = 0.029). T-SPOT.TB test positivity was higher in the group that had encountered active TB patients (p = 0.033). However, no significant difference was found between T-SPOT.TB results according to BCG vaccine, albumin, urea and lymphocyte levels. Although T-SPOT.TB test positivity was higher in patients with a previous TB finding in a PA chest X-ray, there was no statistically significant difference (p = 0.093). The applicability of the TST in the diagnosis of latent TB infection in HD patients is difficult and it is likely to give false-negative results. The T-SPOT.TB test is not affected by the BCG vaccine and immunosuppression. Therefore, using the T-SPOT.TB test would be a more appropriate and practical approach in the diagnosis of latent TB in HD patients.

The prevalence of latent tuberculosis infection in patients with chronic kidney disease: A systematic review and meta-analysis

Objective

To estimate the prevalence of latent tuberculosis infection (LTBI) in chronic kidney disease (CKD) patients.

Methods

This study was conducted following the PRISMA guidelines. We identified, 3694 studies from the whole search, and 59 studies were included. Each study's quality was assessed using JBI checklist. We employed STATA version 17 for statistical analysis. We assessed heterogeneity using I2 heterogeneity test. Publication bias was assessed using funnel plot and Egger's test. We estimated the pooled LTBI prevalence in CKD patients along with 95%CI.

Results

The pooled prevalence of LTBI among CKD patients using data collected from 53 studies having 12,772 patients was 30.2% (95%CI; 25.5, 34.8). The pooled prevalence among pre-dialysis, hemodialysis, peritoneal dialysis, and renal transplanted patients was 17.8% (95%CI; 3.3, 32.4), 34.8% (95%CI; 29.1, 40.5), 25% (95%CI; 11, 38), and 16% (95%CI; 7, 25), respectively. The pooled prevalence of LTBI stratified by the laboratory screening methods was 25.3% (95%CI: 20.3-30.3) using TST, 28.0% (95%CI; 23.9-32.0) using QFT, and 32.6%, (95%CI: 23.7-41.5) using T-SPOT.

Conclusion

There is high prevalence of LTBI among CKD patients mainly in patients on dialysis. Thus, early diagnosis and treatment of LTBI in CKD patients should be performed to prevent active TB in CKD patients.PROSPERO registration number: CRD42022372441.