Need for Different Cutoff Values for Reading Mantoux Test with 2TU and 5TU PPD

Ramaraj, Savitha Mysore; Nagendra, Kanchana; Gopal, Girish; Majgi, Sumanth Mallikarjuna

doi:10.1007/s12098-017-2363-8

Cited by 5 publications

(3 citation statements)

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“…Also the results vary with different strengths of PPD used for TST. Studies from India have shown that cutaneous hypersensitivity to 1TU or 2TU PPD or 5TU PPD are not comparable [ 16 , 17 ]. However a study from Philippines on TST reactivity among children with TB, found 2 TU PPD RT-23 to be comparable with 5 TU PPD-S and that one can be used instead of the other in routine Mantoux testing [ 18 ].…”

Section: Discussionmentioning

confidence: 99%

Tuberculin skin test and QuantiFERON-Gold In Tube assay for diagnosis of latent TB infection among household contacts of pulmonary TB patients in high TB burden setting

et al. 2018

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BackgroundWorld Health Organization (WHO) recommends systematic screening of high-risk populations, including household contacts (HHCs) of adult pulmonary tuberculosis (TB) patients, as a key strategy for elimination of TB. QuantiFERON-TB Gold In-Tube (QFT-GIT) assay and tuberculin skin test (TST) are two commonly used tools for the detection of latent tuberculosis infection (LTBI) but may yield differential results, affecting eligibility for TB preventive therapy.Materials and methodsA prospective cohort study of adult pulmonary TB patients and their HHCs were recruited in 2 cities of India, Pune and Chennai. HHCs underwent QFT-GIT (QIAGEN) and TST (PPD SPAN 2TU/5TU). A positive QFT-GIT was defined as value ≥0.35 IU/ml and a positive TST as an induration of ≥5 mm. A secondary outcome of TST induration ≥10mm was explored. Proportion positive by either or both assays, discordant positives and negatives were calculated; test concordance was assessed using percentage agreement and kappa statistics; and risk factors for concordance and discordance including age categories were assessed using logistic regression. Sensitivity and specificity was estimated by latent class model.ResultsOf 1048 HHCs enrolled, 869 [median (IQR) age: 27 years (15–40)] had both TST and QFT-GIT results available and prevalence of LTBI by QFT-GIT was 54% [95% CI (51, 57)], by TST was 55% [95% CI (52, 58)], by either test was 74% [95% CI (71, 77) and by both tests was 35% [95% CI (31, 38)]. Discordance of TST+/QFT-GIT- was 21% while TST-/QFT-GIT+ was 26%. Poor to fair agreement occurred with TST 5mm or 10mm cutoff (60 and 61% agreement with kappa value of 0.20 and 0.25 respectively). Test agreement varied by age, TST strength and induration cut-off. In multivariate analysis, span PPD was a risk factor for QFT-GIT+ and TST- while absence of BCG scar was for TST+ and QFT-GIT-. Being employed and exposure to TB case outside the household case were associated with positivity by both the tests. Sensitivity of TST and QFT-GIT to diagnose LTBI was 77% and 69%. Probability of having LTBI was >90% when both tests were positive irrespective of exposure gradient.ConclusionPrevalence of LTBI among HHCs of adult pulmonary TB patients in India is very high and varies by test type, age, and exposure gradient. In our high TB burden setting, a strategy to treat all HHCs or a targeted strategy whereby an exposure index is used should be assessed in future preventive therapy and vaccine studies as HHCs have several factors that place them at high risk for progression to TB disease.

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Section: Discussionmentioning

confidence: 99%

Tuberculin skin test and QuantiFERON-Gold In Tube assay for diagnosis of latent TB infection among household contacts of pulmonary TB patients in high TB burden setting

et al. 2018

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“…They found that Mantoux reaction was significantly higher at 72 h compared to the reaction at 48 h. They came to conclusion that in clinical practice, Mantoux test should be read at 72 h as readings at 48 h may underestimate the size of the reaction. [8] Lee and Oh indicated that a new criteria for tuberculin reactivity to 2 TU are to be established in future studies. [4] In a study by Ramaraj et al, authors proposed a formula to make the reactions of 5 TU comparable to that of 2 TU which is, 5 TU = 2 TU × 0.9 + 2.82.…”

Section: Discussionmentioning

confidence: 99%

“…They also had an opinion that further studies with a larger sample size and positive cases were required to recommend this formula for the population and the same cutoff of 10 mm or more is not applicable to both 5 TU and 2 TU strength of PPD. [8]…”

Section: Discussionmentioning

confidence: 99%

A Comparative Study of Tuberculin Reactions to 2 TU and 5 TU of Purified Protein Derivative in a Tertiary Care Center

Chinthana¹,

Gowda²,

Narendra³

et al. 2021

JMSH

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Introduction: Globally, tuberculosis (TB) is the second leading cause of deaths related to an infectious disease, after HIV. Tuberculin skin testing (TST) which is also called Mantoux test or purified protein derivative (PPD) test remains a useful tool to diagnose TB in children. Current recommendation is to use 2 TU PPD RT23 for all diagnostic purposes. TST or Mantoux test is considered positive if the induration is 10 mm or more. Due to non-availability of 2 TU, unstandardized TST with 5, 10 TU RT23 is in practice which can cause problems in reading of test results. Objectives: The objectives of the study were to compare the tuberculin reaction sizes to 2 TU and 5 TU doses of RT 23 with Tween 80 at 46–48 h and 76–78 h. Methodology: All children who were aged < 18 years and are known case of TB were included in the study. Each child was administered dual intradermal injections with 2 TU and 5 TU doses of tuberculin on the volar aspect of the forearm until a wheal was visible at the injected area. The reactions to both the tests were read at 46–48 h and 70–72 h. Institutional Ethics Committee approval was taken before start of the study. The statistical analysis was performed using SPSS 22 version software. Results A total number of cases included in the study during the study period were 81 cases, out of which 52 (64.19%) were male and 29 (35.8%) were female. Among those 81 cases, the mean reaction to 2 TU at 46–48 h was 12.79 mm and at 76–78 h was 15.33 mm. The mean reaction to 5 TU at 46–48 h was 18.89 mm and at 76–78 h was 22.80 mm. Among the cases, the mean size of induration at 46–48 h was lesser than that of 76–78 h in both 2 TU and 5 TU and it was statistically significant. Reactions to 2 TU and 5 TU PPD can be made comparable using the equation, 5 TU = (2 TU × 0.599) + 11.233 at 46–48 h and 5 TU = (2 TU × 0.074) + 21.66 at 76–78 h. ConclusionThus to conclude, cutaneous hypersensitivity to 2 TU PPD can be made comparison using the equation, 5 TU = (2 TU × 0.

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Strength of Tuberculin Used in the Mantoux Test: Does It Make a Difference?

Mathew

2017

Indian J Pediatr

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Need for Different Cutoff Values for Reading Mantoux Test with 2TU and 5TU PPD

Abstract: Cutaneous hypersensitivity to 2TU PPD is not comparable to that of 5TU PPD.

Cited by 5 publications

References 1 publication

Tuberculin skin test and QuantiFERON-Gold In Tube assay for diagnosis of latent TB infection among household contacts of pulmonary TB patients in high TB burden setting

Tuberculin skin test and QuantiFERON-Gold In Tube assay for diagnosis of latent TB infection among household contacts of pulmonary TB patients in high TB burden setting

A Comparative Study of Tuberculin Reactions to 2 TU and 5 TU of Purified Protein Derivative in a Tertiary Care Center

Strength of Tuberculin Used in the Mantoux Test: Does It Make a Difference?

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