Background HIV infection is the strongest single risk factor for the development of active tuberculosis (TB) in individuals with latent TB infection (LTBI).1 NICE guidelines recommend screening HIV-positive patients for LTBI with an Interferon Gamma Release Assay (IGRA), plus a Tuberculin Skin Test (TST) in patients with a CD4 count <200 cells/mm3 if IGRA negative.
Method We began screening HIV-positive patients for LTBI in July 2011; this prospective study reports our 3 year data. Patients had an IGRA (T-SPOT. TB®), and a TST was performed in those with a negative result and a CD4 count <200 cells/mm3.
Results 116 HIV-positive patients were screened (Table 1):
CD4 Count ≥200 Group Of 88 patients, 4 (5%) had a history of previous TB infection and were excluded. 70/84 (83%) had a negative IGRA, 9/84 (11%) had a positive IGRA (3 had active TB and 6 LTBI) and 5/84 (6%) had inconclusive IGRA results. Of these, 4/5 had a repeat IGRA (2 positive, 1 negative, 1 awaited) and 1 was lost to follow up.
CD4 Count <200 Group Of 28 patients, 1 (4%) had a history of previous TB infection and was excluded. 24/27 (89%) had a negative IGRA and were referred to TB clinic for a TST. Of these, 18/24 (75%) had a negative TST, 3/24 (12.5%) did not attend and 3/24 (12.5%) are awaiting appointments. 2/27 (7%) had a positive IGRA and were treated for LTBI. One (4%) had an inconclusive IGRA result but did not attend follow up.
Conclusions Screening for TB in HIV is worthwhile, with a 12% detection rate in our cohort. Performing a TST did not detect any additional cases of TB infection in the CD4 <200 group. Performing this test is time-consuming, costly and inconvenient, and we suggest that screening should be with an IGRA alone. The detection rate of TB infection was lower in those with more advanced immunocompromise, which raises concern about the sensitivity of the screening tests.
Treatment of latent tuberculosis infection in HIV infected persons. Akolo C, Adetifa I et al. Cochrane Database of Systematic Reviews 2010, Issue 1
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