Reaction size in tuberculin test positivity in hemodialysis patients - Authors’ reply

Sir,

We would like to thank the authors[1] for comments on our manuscript.[2] According to the 1995, Centers for Disease Control (CDC) recommendations[3] about the size of reaction of tuberculin skin test for diagnosing latent tuberculosis (TB) in high risk population >5 mm size is restricted to only three situations: persons who have had recent close contact with persons who have active TB, persons who have human immunodeficiency virus (HIV) infection or risk factors for HIV infection but unknown HIV status, and those with fibrotic chest radiographs consistent with healed TB. In all other medical conditions including organ transplant, the size of reaction for diagnosis of latent TB was 10 mm. In a revision in 2005,[4] organ transplant recipients, and other immunosuppressed persons (e.g., persons receiving >15 mg/day of prednisone for >1 month) and TB suspects were added in the list of condition where criteria of >5 mm was applicable. However, even in 2005, chronic renal failure and other medical conditions still required >10 mm reaction for the diagnosis of latent TB. Further, in almost all studies on diagnosis of latent TB based on skin test in a dialysis population, >10 mm size has been used.

Thus, we do not feel that the basis of taking >5 mm reaction criteria for diagnosis of latent TB in dialysis populations will be appropriate.