Z Gastroenterol 2008; 46 - A7
DOI: 10.1055/s-2008-1081514

Discrepant results between routine screening for latent tuberculosis (TB) and Quantiferon® in patients with inflammatory bowel diseases (IBD)

P Papay 1, A Eser 1, P Paulinska 1, C Lichtenberger 1, A Mikulits 1, W Miehsler 1, C Dejaco 1, G Novacek 1, H Vogelsang 1, W Reinisch 1
  • 1Department of Internal Medicine III, Division of Gastroenterology and Hepatology, Medical University of Vienna, Austria

Background/Aim:

Screening for latent TB is part of the routine management in patients with IBD before starting therapy with any anti-Tumor Necrosis Factor (TNF)! compound. Recently, the whole blood interferon “ assay (QuantiFERON®) has been introduced as additional test to routine screening consisting of tuberculin skin test (TST) and chest X-ray. Our aim was to compare these diagnostic methods in consecutive IBD patients with the indication of anti TNF! therapy.

Patients/Methods:

To date, 78 patients with IBD, who started treatment with infliximab, adalimumab or certolizumab were screened for latent tuberculosis by performing chest x-ray, TST and QuantiFERON®. Signs indicative of latent TB from chest x-ray included granuloma, bihilar lymphadenopathy and pleura scarring. TST was assessed positive if induration >5mm appeared after 48–72h of intracutan application of tuberculin/5 units in 0,1ml/. QuantiFERON® was positive if quantitative measurement revealed >0,35.

Results:

QuantiFERON® test failed on samples from 12/78 patients, resulting in 66/78 (85%) patients on whom results from all 3 screening tests were available. Chest X-ray revealed findings indicative for latent TB in 3/78 (4%) subjects. All of them were positive for TST, but negative for QuantiFERON®. Of note, 2 of those patients received INH previously.

Table shows proportion of dis-/concordance between TST and QuantiFERON®.

Concordance between TST and QuantiFERON® was observed in 51 cases (77%), discordance in 15 (23%). A positive result in any of the 3 tests prompted prophylactic therapy for latent TB with isoniazid in 15/66 (19%) patients. No single case of active TB was reported by now.

Conclusion:

Our results reveal frequently discordant findings from TST and QuantiFERON®. Hence, we speculate that with current guidelines for TB screening, consisting of chest X-ray and TST, substantial proportions of patients may receive over- or under-treatment with isoniazid. Larger studies on the prognostic impact of those findings are urgently warranted.

QuantiFERON® positive

QuantiFERON® negative

TST positive

4/66 (6%)

11/66 (17%)

15

TST negative

4/66 (6%)

47/66 (71%)

51

8

58

66