163 tst

163 tst

What is the TST and QFT cut off for tuberculin?

163.6  76.0–310.7  TST and QFT categories are based on a TST cutoff of 10 mm and a QFT cutoff of 0.35 IU/ml. Abbreviations: QFT, QuantiFERON Gold In-Tube test; TST, tuberculin skin test. aParticipants were followed prospectively for 2 years and retrospectively for 4 additional years.

How many TST positive and negative TST values are there?

18 438  21.7  6.9–52.3  TST positive, QFT negative  0  7368  0  TST negative, QFT positive  1  1734  57.7  28.9–284.4  QFT and TST positive 

How many QFT and TST positive events have there been?

7368  0  TST negative, QFT positive  1  1734  57.7  28.9–284.4  QFT and TST positive  8  4890  163.6  76.0–310.7  Events, n.

Does QFT-G test detect tuberculosis infection in untreated culture-confirmed tuberculosis?

In direct comparisons, the sensitivity of QFT-G was statistically similar to that of the tuberculin skin test (TST) for detecting infection in persons with untreated culture-confirmed tuberculosis (TB).

What is the difference between TST and QFT skin tests?

Tuberculin skin testing (TST) has been used for years as an aid in diagnosing latent tuberculosis infection (LTBI) and includes measurement of the delayed type hypersensitivity response 48--72 hours after intradermal injection of PPD. TST and QFT do not measure the same components of the immunologic response and are not interchangeable.

Is it safe to repeat a tuberculin skin test?

In general, there is no risk associated with repeated tuberculin skin test placements. If a person does not return within 48-72 hours for a tuberculin skin test reading, a second test can be placed as soon as possible. There is no contraindication to repeating the TST, unless a previous TST was associated with a severe reaction.

How long does it take to get QFT results after TST?

This varies and depends on how frequently the laboratory in your area carries out the test. Results can be available in 24 hours. Unlike the TST, individuals do not need to return 2–3 days later in order to have the test read. Does a prior TST influence a QFT result?

What does a positive QFT result indicate?

• A positive QFT result suggests that current M. tuberculosisinfection is likely. The result does not differentiate between recently acquired or old infection, or between LTBI and active tuberculosis.

How are QFT results interpreted in the workup of tuberculosis (TB)?

Interpretation of QFT results (Table 2) is stratified by estimated risk for infection with M. tuberculosis, in a manner similar to that used for interpreting TST with different cut-off values. QFT results indicative of M. tuberculosis infection include the following three criteria: (mitogen -- nil) and (tuberculin -- nil) are both > 1.5 IU; and

What is the difference between TST and QFT?

Specificity is defined as the probability that the test indicates an individual does not have the disease, or infection, when in fact they are disease free. QFT has been shown to have >99% specificity compared to lower than 70% for the TST in some settings.

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