The Case Against Anergy Testing as a Routine Adjunct to Tuberculin Skin Testing

Abstract

Although anergy testing is commonly used to help interpret negative tuberculin skin test results, the validity of this approach has not been demonstrated. Specific issues include lack of a standardized protocol for antigen selection, number needed to reliably evaluate inability to respond, and uniform criteria for defining cutaneous reactivity, as well as regional variation in skin test reactivity. Tuberculin skin testing is used to screen for latent infection and to evaluate the need for isoniazid prophylaxis. The presence or absence of reactivity to control antigens does not affect this decision. The results of anergy testing also do not predict the risk for progression to active disease in either HIV-negative or HIV-positive patients. In HIV-negative patients with active tuberculosis, 10% to 20% have negative tuberculin test results, and 5% to 10% have a negative tuberculin result but have a positive reaction to another antigen. A negative tuberculin skin test result does not exclude either latent infection or active disease, even in the presence of a reaction to other antigens. Neither anergy testing nor tuberculin testing obviates the need for microbiologic evaluation when there is suspicion for active tuberculosis infection. Therefore, anergy testing is not useful in screening for asymptomatic tuberculous infection or for diagnosing active tuberculosis.

Risk of tuberculosis in dialysis patients: association of tuberculin and 2,4-dinitrochlorobenzene reactivity with risk of tuberculosis

“…Control tests with antigens for candida, mums and tetanus toxoid are the most commonly used by the investigators [11]. However, the validity of this approach has not been proved [12]. In this study, skin anergy and the subsequent potential of a false negative Mantoux test were accurately defined with the chemical antigen DNCB.…”

Comparison of Quantiferon-TB Gold With Tuberculin Skin Test for Detecting Latent Tuberculosis Infection Prior to Liver Transplantation

“…Our data suggest that a higher MELD score and a lower lymphocyte count are risk factors for an indeterminate result. We were unable to compare this to the rate of anergy with the TST, because no anergy testing was done based on current guidelines and the limitations of anergy testing (7,22). However, all patients with an indeterminate QFT-G also had a negative TST.…”

Mycobacterium tuberculosis Infection in Recipients of Solid Organ Transplants

“…Despite this fact, PPD testing continues to be the first step in the evaluation of M. tuberculosis infection. The use of anergy skin testing to validate negative PPD test results in immunocompromised patients has been found to be ineffective, although very few transplant recipients are included in these series [21,22].…”