Comparis
Comparison of
Tuberculin Skin Test (TST) and Quantiferon Test (QFT) for detection of
Latent TB infection among Health Care Workers (HCWs) in a Tertiary Care
Hospital in Riyadh, Saudi Arabia.
Nasser AE.
AIHamdan1; Moustafa A.F. Abbas1,2, Mohamed S. AIQahtani3 Suhail
Klantan3; Lamiaa A.Fiala2and Gehad ElGhazali3,4
1 Community Medicine Dept., Faculty of
Medicine, King Fahad Medical City, KSAU-HS, Riyadh, Saudi Arabia
2 Community Medicine Dept., Faculty of Medicine,
Suez Canal University, Ismailia, Egypt
3 King Fahad Medical City, Ministry of Health,
Riyadh, Saudi Arabia
4 SEHA hospital, Abu Dhabi, United Arab Emirates
Abstract: Background: Latent TB Infection is a common finding among HCWs in
the Middle East, that is usually discovered on routine
pre-employment examination or during regular health check, it needs a course of
anti-tuberculous drug medication for months with subsequent side effects.
Tuberculin Skin Test (TST) is the traditional testing method for diagnosing
LTBI, but it has a known high rate of false positive with subsequent needless
loss of time, efforts, loss of productivity and side effects. QFT test has a
higher sensitivity and specificity. Aim: To determine the
sensitivity, specificity, positive and negative predictive value of TST versus
QFT Test as a diagnostic tool for latent TB among new hires of health
care workers at KFMC, Riyadh, Saudi Arabia. Methods: A
descriptive study of 268 new HCWs agreed to participate, questionnaire with
socio-demographic data and work history was filled, and both test were done TST
and QFT test. Recent BCG vaccination and TST result of 5 mm or less were
excluded, since there is a low positive rate. Results: Sensitivity
and specificity of TST at standard 10mm or more to be positive, was 100 % and
53.4% as compared to QFT test. Using different cutoff measurements of size of
TST indurations specificity was improved at the expense of sensitivity; at 13mm
or more, sensitivity, specificity and κ were 95.5%; 73.2 and 0.611
respectively; while at 15mm or more it was 74.8%; 84.1% and 0.605 respectively.
Frequency distribution of sizes of induration according to QFT test results and
ROC curve showed that at 13 mm or more specificity would be improved to 70
percent approximately and sensitivity to be still at 90% approximately.Conclusion: When
comparing TST and QFT, Rates of True negatives and Agreement were improved from
(specificity = 53.4%) and (κ=0.536), to (Specificity=63.9%) and (κ=0.611) when
using a different cut off point for induration sizes of 13 mm or more, rather
than the traditional 10 mm or more cutoff point. Large scale study is required
to confirm such findings in Middle Eastern health care settings.
[Nasser AE. AIHamdan;
Moustafa A.F. Abbas, Mohamed S. AIQahtani. Suhail Klantan; Lamiaa A. Fiala and
Gehad ElGhazali. Comparison of
Tuberculin Skin Test (TST) and Quantiferon Test (QFT) for detection of
Latent TB infection among Health Care Workers (HCWs) in a Tertiary Care
Hospital in Riyadh, Saudi Arabia. Life Sci J 2013;10(1):406-411].
(ISSN: 1097-8135). http://www.lifesciencesite.com. 65
Keywords: Latent TB Tuberculin Skin Test Quantiferon Health Care
Workers Full Text 65
