Major Article
Boosted tuberculin skin testing in hemodialysis patients

https://doi.org/10.1016/j.ajic.2005.12.003Get rights and content

Background

Tuberculosis remains a significant health problem for patients receiving long-term hemodialysis (HD). The tuberculin skin test (TST) is an important method of detecting Mycobacterium tuberculosis infection. Cutaneous anergy decreases the accuracy of the test in these patients. Higher and repeating doses have been mentioned in the immunosuppressed patients. This study examined the significance and frequency of the booster phenomenon in 2-step tuberculin testing of these patients.

Methods

A total of 106 outpatients in a hospital-based HD center in Turkey were screened with 5 and 10 tuberculin units (TU) and Candida antigen. To determine the frequency of booster phenomenon, patients with <10 mm indurations to the initial TST with 5 TU were given a second test with 10 TU, 7 days later.

Results

Forty (37.7%) of 106 patients had a significant tuberculin reaction (≥10 mm) on the initial TST with 5 TU. The booster effect was detected in 16 (24.3%) of 66 patients who had a negative reaction (≤10 mm) to the initial test. Overall, 56 (52.8%) patients showed a significant reaction on both tests. Anergy was found in 39 (36.8%) of 106 patients.

Conclusion

Even with the high rate of anergy, TST seems to be useful for these patients; also, it is inexpensive and easy to perform. We suggest repeating the test with higher doses in patients with a high risk for tuberculosis. Anergy testing with Candida antigen may be helpful in determining the value of TST.

Section snippets

Methods

A total of 106 patients were recruited from Ondokuz Mayıs University School of Medicine, Hemodialysis Unit, Samsun, Turkey. Our dialysis patients had similar social backgrounds, and the majority were from a moderate social class. All underwent dialysis for an average of 4 to 5 hours, 3 times per week. The patients were given an educational handout on TST the week before the testing started, and written consent for testing was obtained. Patient charts were reviewed for demographics (age, sex,

Results

The frequency of TB reactions and anergy were examined in 106 patients. The demographic characteristics are shown in Table 1. Initial tuberculin reactivity was classified into the following 3 ranges of induration: <5 mm (36.8%, n = 39), 5 to 10 mm (25.5%, n = 27), >10 mm (37.7%, n = 40). Reactivity to Candida was classified similarly: <5 mm (95%, n = 37), 5 to 10 mm (42.4%, n = 45), >10 mm (22.6%, n = 24).

Overall, 40 (37.7%) of the 106 patients had a significant tuberculin reaction (≥10 mm) on

Discussion

TB remains a significant health problem for patients receiving long-term HD. These patients are 6 to 16 times more likely to develop active TB than other members of their local community, especially in developing countries.2, 3, 13, 14, 17 Similarly, several studies have shown that the incidence of active TB disease is high among chronic HD patients in Turkey.2, 3, 14, 17 For that reason, there has been an increased awareness of the need to vigorously promote TB control measures, including

References (19)

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    To our knowledge, those are the highest rates of positive reaction to a TST in HD patients that has been published in the literature. Some authors have reported that the percentage of TST positivity in their subjects varied between 16% and 54.7%.2,9–11 The high rate of positive TST results in those areas of Turkey, which is not surprising, could be attributed to several factors.

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