Background: Chronic haemodialysis patients are at increased risk for developing tuberculosis (TB). Appropriate screening methods to detect latent Mycobacterium tuberculosis infection are required. The aim of this prospective multi-centre study was to evaluate the tuberculin skin test (TST) as a screening method for detection of M.tuberculosis infection in haemodialysis patients.
Methods: A total of 224 patients in two haemodialysis centres were prospectively tested, using 2 units of tuberculin PPD RT23. Up to three booster injections were given with a 7 day interval to patients not responding to the previous test. The results were compared with clinical and radiological data.
Results: The cumulative prevalence of a positive TST was 14.7% for the first test, 27.8% for the second test and 32.6% for the fourth test. There was no influence of age, gender, haemodialysis centre, dialysis efficiency, nutritional state, levels of zinc, vitamin D therapy, primary renal disease, (previous or active) immunosuppressive therapy or response to hepatitis B vaccination. There was a significant, but weak, correlation between TST positivity and a history of positive TST or TB. Chest radiography and positive TST were not correlated, yet a positive chest X-ray increased the detection of patients with latent M.tuberculosis infection up to 47.8%.
Conclusions: In haemodialysis patients, a positive response of >30% to repeated TST was obtained. Two consecutive TSTs were sufficient to recruit most of the booster reactions. Since only a weak correlation was found with anamnestic data, regular TST evaluation in combination with a chest X-ray, is a useful tool to detect infection with M.tuberculosis in haemodialysis patients.