The usefulness of QuantiFERON®TB-2G for the diagnosis of tuberculosis in dialysis patients

Background : It is known that the incidence of tuberculosis (TB) in Japan is very high compared to that in Western developed countries, especially among dialysis patients. The high rate of extrapulmonary TB in dialysis patients makes it more difficult to diagnose TB. Recently a new diagnostic technique called QuantiFERON®TB-2G(QFT) was developed and has become available for the general population. This new test is not affected by BCG vaccination status. However, the usefulness of this test in dialysis patients has not yet been examined. Method : We used this technique in thirty-three dialysis patients including 5 active TB patients, 24 non-TB patients and 4 old TB patients. Results : Six patients were positive. Five of the six had active TB and one was an old TB patient. Thirteen patients were negative. Thirteen of fourteen were non-TB patients and one was an old TB patient. We had five middle range patients including three non-TB patients and two old TB patients. Eight patients were indeterminate and none of these eight had either old or active TB. In nine patients, we had difficulty determining the causes of fever or unilateral pleural effusion, five of the nine were QFT-positive and later diagnosed as having extrapulmonary TB. The other four were QFT negative, one had Infectious Endocarditis, one had SLE pleuritis, one had infectious aortic aneurysm and the etiology in the other case was unknown. Conclusion : The findings of this study suggest that QFT is useful for the diagnosis of extrapulmonary TB in dialysis patients.