Warning: fopen(/home/virtual/epih/journal/upload/ip_log/ip_log_2024-12.txt): failed to open stream: Permission denied in /home/virtual/lib/view_data.php on line 95 Warning: fwrite() expects parameter 1 to be resource, boolean given in /home/virtual/lib/view_data.php on line 96 Comparison of the tuberculin skin test and the QuantiFERON-TB Gold test in detecting latent tuberculosis in health care workers in Iran
Skip Navigation
Skip to contents

Epidemiol Health : Epidemiology and Health

OPEN ACCESS
SEARCH
Search

Articles

Page Path
HOME > Epidemiol Health > Volume 38; 2016 > Article
Original Article
Comparison of the tuberculin skin test and the QuantiFERON-TB Gold test in detecting latent tuberculosis in health care workers in Iran
Ehsan Mostafavi1,2*orcid, Mahshid Nasehi3,4*orcid, Abdolrazagh Hashemi Shahraki1,2orcid, Saber Esmaeili1,2,5orcid, Ebrahim Ghaderi6,7orcid, Saeed Sharafi3orcid, Amin Doosti-Irani1,8orcid
Epidemiol Health 2016;38:e2016032.
DOI: https://doi.org/10.4178/epih.e2016032
Published online: July 24, 2016

1Department of Epidemiology, Pasteur Institute of Iran, Tehran, Iran

2Research Centre for Emerging and Reemerging Infectious Diseases, Pasteur Institute of Iran, Akanlu, Kabudar-Ahang, Hamadan, Iran

3Center for Diseases Control and Prevention, Ministry of Health and Medical Education, Tehran, Iran

4Department of Epidemiology and Biostatistics, School of Public Health, Iran University of Medical Sciences, Tehran, Iran

5Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran

6Social Determinants of Health Research Center, Kurdistan University of Medical Sciences, Sanandaj, Iran

7Department of Epidemiology and Biostatistics, School of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran

8Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran

Correspondence: Amin Doosti-Irani  Department of Epidemiology, Pasteur Institute of Iran, 12 Farwardin Ave., Tehran 1316943551, Iran  Tel/Fax: +98-2166496448, E-mail: a_doostiirani@yahoo.com
*Mostafavi and Nasehi have contributed equally to this work as joint first authors.
• Received: July 8, 2016   • Accepted: July 24, 2016

©2016, Korean Society of Epidemiology

This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

prev next
  • 18,818 Views
  • 222 Download
  • 9 Web of Science
  • 9 Crossref
  • 10 Scopus
  • OBJECTIVES:
    The tuberculin skin test (TST) and the QuantiFERON-TB Gold test (QFT) are used to identify latent tuberculosis infections (LTBIs). The aim of this study was to determine the agreement between these two tests among health care workers in Iran.
  • METHODS:
    This cross-sectional study included 177 tuberculosis (TB) laboratory staff and 67 non-TB staff. TST indurations of 10 mm or more were considered positive. The Student’s t-test and the chi-square test were used to compare the mean score and proportion of variables between the TB laboratory staff and the non-TB laboratory staff. Kappa statistics were used to evaluate the agreement between these tests, and logistic regression was used to assess the risk factors associated with positive results for each test.
  • RESULTS:
    The prevalence of LTBIs according to both the QFT and the TST was 17% (95% confidence interval [CI], 12% to 21%) and 16% (95% CI, 11% to 21%), respectively. The agreement between the QFT and the TST was 77.46%, with a kappa of 0.19 (95% CI, 0.04 to 0.34).
  • CONCLUSIONS:
    Although the prevalence of LTBI based on the QFT and the TST was not significantly different, the kappa statistic was low between these two tests for the detection of LTBIs.
It is estimated that one-third of the world’s population currently has a latent tuberculosis infection (LTBI) as a result of infection with Mycobacterium tuberculosis [1]. It is estimated that approximately 10% of individuals with an LTBI may develop active tuberculosis (TB) during their lifetime [2]. The timely detection of LTBIs is important to prevent the development of active TB [3].
The tuberculin skin test (TST) is the most commonly used test to identify LTBIs. Although the TST is inexpensive and simple, facilitating its use, especially in developing countries, the validity and reliability of the TST is affected by many factors, including Bacillus Calmette-Guérin (BCG) vaccination, infection with non-TB Mycobacterium (NTM) species, the method of TST administration, the interpretation of the reaction, insufficient dosage, and cutaneous anergy [4-7].
In recent years, the QuantiFERON-TB Gold test (QFT), which is one of the newly developed interferon-gamma release assays (IGRAs) used to diagnose TB infections, has been used extensively for the detection of latent TB [8]. The test identifies the level of interferon (IFN)-gamma produced in reaction to M. tuberculosis-specific antigens [9]. IGRAs have several important advantages over the TST. The most important advantage of IGRAs is that, unlike TST, they are not influenced by factors such as BCG vaccination, most NTM species, or antigen dose [8,10]. Nevertheless, IGRAs have some important disadvantages, such as involving additional material costs and requiring a well-equipped laboratory and blood sampling with subsequent special handling to preserve the viability of lymphocytes [8]. However, IGRAs have a high specificity and a similar sensitivity to the TST for the detection of LTBIs [10,11].
Studies have shown poor agreement between IGRAs and the TST [12-14]. However, in countries with a high incidence of TB, an acceptable level of agreement has been reported between the TST and IGRA. In contrast, studies conducted in countries with an annual incidence of TB of ≤20 per 100,000 have found poor agreement between the QFT and the TST [15]. More evidence is therefore needed to evaluate discrepancies in the results between IGRAs and the TST [10].
Given the lack of evidence regarding instances of disagreement between the TST and IGRAs in the detection of LTBIs among health care workers (HCWs) in Iran, the aim of this study was to determine the agreement between these two tests among Iranian HCWs.
A proposal for this study was approved by the scientific committee of the Pasteur Institute of Iran. This cross-sectional study was performed between November 2013 and January 2014 in eight universities of the medical sciences, including Shiraz, Golestan, Shahid Beheshti, Iran, Tehran, Tabriz, Kermanshah, and Isfahan. All of these universities contain regional reference TB laboratories performing microscopic examinations, cultures, and drug sensitivity testing on M. tuberculosis isolates from throughout Iran.
In this study, all TB laboratory staff (177 participants) and a random sample of non-TB staff (67 participants), including administrative, finance, and service staff were included. Pregnant women were excluded from this study. A questionnaire was used to gather information regarding demographic variables, place and history of work, history of contact with TB patients, the presence of a BCG vaccination scar, and history of purified protein derivative skin tests.
Trained staff injected 0.1 mL (5 tuberculin units) of human tuberculin (Razi Vaccine and Serum Research Institute, Karaj, Iran) intradermally into the dorsal or volar surface of the forearm. The TST response after 48 to 72 hours was read by a trained technician. TST reactions of ≥10 mm were considered positive, while reactions of <10 mm were interpreted as negative [6].
The QFT was performed using a blood sample. Blood samples were obtained before the TST. At least 3 mL of blood was obtained from each participant, and then a 1-mL blood sample was transferred into each of three QuantiFERON-TB Gold tubes (Cellestis Ltd., Victoria, Australia). Blood samples with test antigens were incubated for 16 to 24 hours based on the kit instructions. The plasma samples were harvested into new labeled tubes and were delivered to the Pasteur Institute of Iran through a 4°C cold chain. The concentration of IFN-gamma (IU/mL) was measured using an automated enzyme-linked immunosorbent assay. The results of the test were interpreted using software supplied by the manufacturer (Cellestis Ltd.) including a cut-off point for the detection of IFN-gamma.
The individuals who had positive TST or QFT results were visited by an expert specialist physician. Active TB was diagnosed based on clinical findings, such as general symptoms (including fatigue, malaise, fever, weight loss, and anorexia) and chronic, productive cough with purulent sputum, in combination with a chest X-ray with radiological features consistent with TB disease.
The prevalence of LTBIs was estimated with 95% confidence intervals (CIs) using the QFT and TST. The concordance between these two tests was evaluated using proportion agreement and the kappa (κ) statistic. The κ statistic was interpreted as follows: κ>0.75 was considered to indicate excellent agreement, κ<0.40 to indicate poor agreement, and κ between 0.40 and 0.75 to indicate fair to good agreement [16].
Both the Student’s t-test and the chi-square test were used to compare means and proportions of variables between the TB laboratory staff and the non-TB laboratory staff. Logistic regression was used to identify risk factors associated with positive results for each test. Unadjusted and adjusted odds ratios (ORs) were reported to assess the effects of covariates on LTBI incidence. All statistical analyses were conducted using Stata version 11.0 (Stata Corp., College Station, TX, USA) and the results were reported with 95% CIs.
In this study, 244 participants, including 177 TB laboratory staff and 67 non-TB staff, were assessed for LTBIs using both the TST and QFT. The mean age of the TB lab staff and the non-TB staff was 36.75 years (standard error [SE], 0.54) and 39.40 years (SE, 1.15), respectively. Males comprised 60.25% (147 of 244) of the participants (Table 1).
The total estimated prevalence of LTBIs based on the TST was 16% (95% CI, 11% to 21%). The prevalence of LTBIs based on the TST among males was significantly higher than among females (p<0.05). Additionally, the prevalence of LTBIs based on this test increased with age, as subjects ≥50 years old had a higher prevalence of LTBIs (p<0.05) (Table 2).
Logistic regression analysis showed the adjusted OR for TB lab staff in comparison to non-TB staff to be 0.31 (95% CI, 0.11 to 0.93). The adjusted OR for participants who had a history of contact with TB patients was 1.70 (95% CI, 0.71 to 4.05), and positive TST results among participants with a history of BCG vaccination were more common than among those with no such history (OR, 2.23; 95% CI, 0.67 to 7.43) (Table 3).
The difference in the prevalence of LTBIs measured using the QFT was not statistically significant across any subgroups. The total estimated prevalence of LTBIs based on the QFT was 17% (95% CI, 12% to 21%). The prevalence of LTBIs among TB lab staff and non-TB staff was 19% (95% CI, 12% to 24%) and 13% (95% CI, 5% to 23%), respectively (Table 2).
According to the adjusted logistic regression, subjects with a history of work of 20 years or more were more likely to have positive QFT results than subjects with a history of work of zero to four years (OR, 2.64; 95% CI, 0.53 to 13.09). Participants with a history of BCG vaccination were less likely to be QFT-positive than others (OR, 0.50; 95% CI, 0.21 to 1.23) (Table 3).
The overall agreement and κ statistic were 77.46% and 0.19 (95% CI, 0.04 to 0.34), respectively. Both the TST and QFT were positive in 13 and negative in 176 subjects (Table 4).
The results of this study showed that the estimated prevalence of LTBIs according to the QFT and the TST was 17% and 16%, respectively. The estimated value of agreement between the QFT and the TST was 77.46%, and the κ statistic was 0.19 (95% CI, 0.04 to 0.34).
The logistic regression analysis indicated different adjusted ORs associated with the QFT and the TST. The adjusted OR for people with ≥20 years of work history was 2.64 times the baseline for the QFT and 0.54 times the baseline for the TST. These results were, however, not statistically significant due to the low sample size of this subgroup.
Another study among Iranian HCWs reported agreement and a κ statistic of 73.8% and 0.39 between the tests, respectively [17]. The agreement between the two tests (TST and QFT) was very similar in that study and our study, but the κ statistic was higher in their study. This discrepancy may reflect differences in the study population. The prevalence of TB in different regions of Iran is not the same [18-21], and the κ statistic is influenced by the prevalence of a disease [22]. In the previous study [17], all subjects were HCWs in a hyper-endemic region. Although the overall agreement between the two tests was good, it is important to note that the measures of agreement have an important limitation; namely, these measures do not take into account the possibility that agreement may occur by chance alone [16].
In another study among HCWs in France, the agreement between the QFT and the TST was weak, and the κ value was 0.11 [23]. In a study of HCWs in Turkey, the overall agreement and κ statistic were 63.1% and 0.22, respectively [24]. The κ statistic between the QFT and the TST was found to be 0.22 in South Korean HCWs [25]. Among HCWs in the US, the agreement and κ value between the QFT and TST were 63.2% and 0.31 (95% CI, 0.27 to 0.35), respectively [26]. The κ value between the QFT and TST in these studies [17,23-26] is almost the same as was found in our study and indicates poor agreement between the QFT and the TST.
According to the results of a meta-analysis, the κ statistic between the QFT and TST among HCWs in countries with a high burden of TB (0.38) was significantly more than has been observed in low-burden countries (0.21) [27]. Therefore, it might be concluded that the agreement of the QFT and TST in populations with a high risk of TB infection seems to be better than in low-risk populations. However, in the high-risk population investigated in the current study, the agreement was also found to be poor. The differences in the κ statistic among various studies may be due to differences in the prevalence of LTBIs in various study populations. Moreover, one of the limitations of the κ statistic is its dependence on prevalence; namely, the κ statistic is higher in populations in which the prevalence is high than in populations with a lower prevalence [16].
One study [17] showed that a family history of TB was a potential risk factor for LTBI based on the QFT (OR,7.96) and TST (OR, 4.91). We did not observe any analogous findings. In our study, the adjusted OR for contact with TB patients was 0.73 (95% CI, 0.34 to 1.56) for the QFT and 1.70 (95% CI, 0.71 to 4.05) for the TST. One reason for this may be the availability and use of suitable protection while working with patients and/or their sputum samples. In the patients’ family members, contact was not found to be protective.
BCG vaccination had a non-significant protective association with LTBIs based on the QFT (OR, 0.50; 95% CI, 0.21 to 1.23), while the association of BCG vaccination with LTBI based on the TST was not significant (OR, 2.23; 95% CI, 0.67 to 7.43). This inconsistency may be due to the influence of BCG vaccination on the results of the TST, since other studies have shown that the results of the TST were influenced by BCG vaccination [8,10]. In a study among HCWs in the US, a positive TST with a negative QFT was associated with BCG vaccination (OR, 25.1; 95% CI, 15.5 to 40.5) [26].
This study was conducted in eight universities of medical science in Iran. All QFT samples were sent to the Department of Epidemiology of the Pasteur Institute of Iran, and the tests were performed by a trained lab expert. The TST tests were conducted by different lab experts and technicians in the eight universities. Although we trained all lab experts and technicians in the method of TST testing, heterogeneity may exist in TST testing by multiple lab experts and technicians, so this factor may have affected the results of the TST test.
The prevalence of LTBIs according to both the QFT and TST was considerable. Although the prevalence of LTBIs based on the QFT and TST was not significantly different, and the overall agreement between both tests was good, the κ statistic was low between these two tests. The κ value among the non-BCG vaccinated group was higher than among the vaccinated group. It seems the use of the QFT test, due to its high cost, is only appropriate in cases where the results of a TST could be affected by BCG vaccination or NTM species.
We would like to thank all TB staff members who participated, as well as the staff of the TB office of the Center for Disease Control of the Ministry of Health and Medical Education. This study was supported by grants from the United Nations Development Programme (UNDP), no. PSC/13/10.

The authors have no conflicts of interest to declare for this study.

Table 1.
Demographic characteristics of the participants
TB lab staff
Non-TB staff
p-value Total
n % n %
Sex
 Male 100 56.50 47 70.15 0.05 147
 Female 77 43.50 20 29.85 97
Age (yr)
 20-29 29 15.85 10 14.93 0.31 39
 30-39 86 46.99 26 38.81 112
 40-49 56 30.60 22 32.84 78
 ≥50 12 6.56 9 123.43 21
Education level
 No high school diploma 17 9.60 12 17.91 0.001 29
 High school diploma 13 7.34 30 44.78 43
 Associate degree 59 33.33 8 11.94 67
 BS 74 41.81 16 23.88 90
 Master of science and above 14 7.91 1 1.49 15
Job
 Lab position requiring a BS 85 48.02 - - 0.001 85
 Technician 60 33.90 - - 60
 Service personnel in lab 32 18.08 - - 32
 Administrative staff - - 42 62.69 42
 Finance staff - - 10 14.93 10
 Service personnel - - 15 22.39 15
History of work (yr)
 0-4 62 35.03 14 20.90 0.001 76
 5-9 42 23.73 10 14.93 52
 10-14 36 20.34 12 17.91 48
 15-19 25 14.12 13 19.40 38
 ≥20 12 6.78 18 26.87 30
History of BCG vaccination 159 89.83 50 74.63 209

TB, tuberculosis; BS, bachelor of science; BCG, Bacillus Calmette-Guérin.

Table 2.
Comparison of the prevalence of LTBIs according to the QFT and TST
Variable QFT
p-value TST
p-value p-value1
Prevalence 95% CI Prevalence 95% CI
Sex
 Male 0.17 0.11, 0.23 0.92 0.20 0.13, 0.26 <0.05 0.46
 Female 0.18 0.10, 0.25 0.10 0.04, 0.16 0.22
Age (yr)
 20-29 0.10 0.03, 0.24 0.13 0.03 0.00, 0.13 <0.05 0.16
 30-39 0.17 0.10, 0.25 0.16 0.10, 0.25 0.86
 40-49 0.23 0.14, 0.34 0.22 0.13, 0.33 0.85
 ≥50 0.05 0.00, 0.24 0.23 0.08, 0.47 0.07
Education level
 No high school diploma 0.21 0.06, 0.36 0.68 0.28 0.11, 0.44 0.49 0.54
 High school diploma 0.09 0.00, 0.18 0.12 0.02, 0.21 0.50
 Associate degree 0.18 0.09, 0.27 0.16 0.07, 0.25 0.82
 BS 0.18 0.10, 0.26 0.13 0.06, 0.20 0.54
 Master of science and above 0.27 0.03, 0.50 0.20 0.01, 0.41 0.67
Job group
 TB lab staff 0.19 0.12, 0.24 0.34 0.14 0.09, 0.19 0.20 0.25
 Non-TB staff 0.12 0.05, 0.22 0.21 0.11, 0.31 0.39
Job
 Lab position requiring a BS 0.19 0.10, 0.27 0.78 0.14 0.07, 0.22 0.58 0.54
 Technician 0.17 0.07, 0.26 0.17 0.07, 0.26 0.81
 Service personnel in lab 0.22 0.07, 0.37 0.09 0.01, 0.20 0.17
 Administrative staff 0.14 0.04, 0.25 0.19 0.07, 0.31 0.56
 Finance staff - - 0.10 0.09, 0.30 0.31
 Service personnel 0.20 0.01, 0.41 0.33 0.09, 0.58 0.41
History of work (yr)
 0-4 0.16 0.07, 0.24 0.42 0.11 0.03, 0.18 0.46 0.34
 5-9 0.15 0.05, 0.24 0.13 0.04, 0.22 0.78
 10-14 0.19 0.07, 0.30 0.21 0.09, 0.33 0.62
 15-19 0.16 0.04, 0.28 0.18 0.06, 0.31 0.56
 ≥20 0.23 0.08, 0.38 0.22 0.08, 0.39 1.00
BCG vaccination
 No 0.26 0.11, 0.40 0.15 0.11 0.01, 0.22 0.42 0.12
 Yes 0.16 0.11, 0.21 0.17 0.12, 0.22 0.79
Total 0.17 0.12, 0.21 0.16 0.11, 0.21 0.90

LBTI, latent tuberculosis infection; TST, tuberculin skin test, QFT, QuantiFERON-TB Gold test; CI, confidence interval; TB, tuberculosis; BS, bachelor of science; BCG, Bacillus Calmette-Guérin.

1 For the comparison of the TST and QFT in each subgroup.

Table 3.
Results of the TST and QFT according to probable risk factors
Variable QF
TST
Unadjusted p-value Adjusted p-value Unadjusted p-value Adjusted p-value
Sex
 Female 1.00 1.00 1.00 1.00
 Male 0.96 (0.49, 1.90) 0.89 0.98 (0.46, 2.07) 0.94 2.14 (0.99, 4.61) 0.05 1.75 (0.75, 4.08) 0.20
Age 1.01 (0.97, 1.05) 0.69 0.99 (0.92, 1.06) 0.77 1.07 (1.02, 1.11) 0.003 1.07 (1.00, 1.15) 0.05
Education Level
 No high school diploma 1.00 1.00 1.00 1.00
 High school diploma 0.39 (0.10, 1.54) 0.15 0.43 (0.10, 1.87) 0.26 0.35 (0.10, 1.19) 0.09 0.40 (0.10, 1.58) 0.19
 Associate degree 0.84 (0.28, 2.49) 0.70 0.81 (0.22, 2.95) 0.75 0.52 (0.18, 1.46) 0.21 1.27 (0.35, 4.55) 0.72
 Bachelor of science 0.83 (0.29, 2.36) 0.69 0.79 (0.22, 2.80) 0.71 0.40 (0.15, 1.12) 0.8 1.02 (0.28, 3.70) 0.98
 Master of science and above 1.40 (0.33, 5.97) 0.66 1.19 (0.23, 6.10) 0.84 0.66 (0.15, 2.95) 0.58 1.75 (0.30, 10.16) 0.53
Job group
 Non-lab staff 1.00 1.00 1.00 1.00
 TB lab staff 1.48 (0.67, 3.28) 0.34 1.88 (0.67, 5.29) 0.23 0.62 (0.30, 1.26) 0.20 2.23 (0.11, 0.93) 0.04
History of work (yr)
 0-4 1.00 1.00 1.00 1.00
 5-9 0.97 (0.37, 2.57) 0.95 1.00 (0.36, 2.74) 0.99 1.32 (0.45, 3.90) 0.61 1.07 (0.35, 3.30) 0.9
 10-14 1.23 (0.47, 3.18) 0.67 1.42 (0.49, 4.13) 0.52 2.24 (0.81, 6.14) 0.12 1.24 (0.41, 3.75) 0.71
 15-19 1.00 (0.34, 2.90) 1.00 1.30 (0.36, 4.61) 0.69 1.92 (0.64, 5.76) 0.25 0.77 (0.21, 2.85) 0.69
 ≥20 1.62 (0.57, 4.62) 0.36 2.64 (0.53, 13.09) 0.24 2.58 (0.84, 7.92) 0.09 0.54 (0.11, 2.68) 0.45
Contact with TB patients
 No 1.00 1.00 1.00 1.00
 Yes 0.95 (0.49, 1.85) 0.87 0.73 (0.34, 1.56) 0.42 1.43 (0.72, 2.84) 0.31 1.70 (0.71, 4.05) 0.23
BCG vaccination
 No 1.00 1.00 1.00 1.00
 Yes 0.54 (0.23, 1.26) 0.15 0.50 (0.21, 1.23) 0.13 1.56 (0.52, 4.70) 0.43 2.23 (0.67, 7.43) 0.19

Values are presented as odds ratio (95% confidence interval).

TST, tuberculin skin test, QFT, QuantiFERON-TB Gold test; TB, tuberculosis; BCG, Bacillus Calmette-Guérin.

Table 4.
Overall agreement and kappa values between the QFT and TST results
Group TST results (cut-off point of ≥ 10 mm) QFT results
Total Agreement (%) Kappa (95%CI) p-value
Negative Positive
TB staff Negative 128 24 152 77.40 0.18 (0.00, 0.35) 0.008
Positive 16 9 25
Total 144 33 177
Non-TB staff Negative 48 5 53 77.61 0.22 (-0.06, 0.50) 0.03
Positive 10 4 14
Total 58 9 67
BCG vaccinated Negative 150 22 172 76.92 0.16 (-0.00, 0.32) 0.01
Positive 26 10 36
Total 176 32 208
Non-BCG vaccinated Negative 25 7 32 75.00 0.18 (-0.16, 0.53) 0.11
Positive 2 2 4
Total 27 9 36
All participants Negative 176 29 205 77.46 0.19 (0.04, 0.34) 0.001
Positive 26 13 39
Total 202 33 244

QFT, QuantiFERON-TB Gold test; TST, tuberculin skin test; CI, confidence interval; TB, tuberculosis; BCG, Bacillus Calmette-Guerin.

  • 1. World Health Organization. Tuberculosis: fact sheet no. 104; 2012 [cited 2014 Nov 26]. Available from: http://www.who.int/mediacentre/factsheets/who104/en/print.html.
  • 2. Comstock GW, Livesay VT, Woolpert SF. The prognosis of a positive tuberculin reaction in childhood and adolescence. Am J Epidemiol 1974;99:131-138.ArticlePubMed
  • 3. Fitzgerald DW, Sterling TR, Has DW. Mycobacterium tuberculosis. In: Mandell GL, Douglas RG, Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett’s principles and practice of infectious diseases. 7th ed. Philadelphia: Elsevier; 2010. p 3129-3159.
  • 4. Farhat M, Greenaway C, Pai M, Menzies D. False-positive tuberculin skin tests: what is the absolute effect of BCG and non-tuberculous mycobacteria? Int J Tuberc Lung Dis 2006;10:1192-1204.PubMed
  • 5. Lee E, Holzman RS. Evolution and current use of the tuberculin test. Clin Infect Dis 2002;34:365-370.ArticlePubMed
  • 6. Huebner RE, Schein MF, Bass JB Jr. The tuberculin skin test. Clin Infect Dis 1993;17:968-975.ArticlePubMed
  • 7. Nayak S, Acharjya B. Mantoux test and its interpretation. Indian Dermatol Online J 2012;3:2-6.ArticlePubMedPMC
  • 8. Mazurek GH, Jereb J, Lobue P, Iademarco MF, Metchock B, Vernon A, et al. Guidelines for using the QuantiFERON-TB Gold test for detecting Mycobacterium tuberculosis infection, United States. MMWR Recomm Rep 2005;54:49-55.PubMed
  • 9. Mazurek GH, Jereb J, Vernon A, LoBue P, Goldberg S, Castro K, et al. Updated guidelines for using interferon gamma release assays to detect Mycobacterium tuberculosis infection - United States, 2010. MMWR Recomm Rep 2010;59:1-25.
  • 10. Menzies D, Pai M, Comstock G. Meta-analysis: new tests for the diagnosis of latent tuberculosis infection: areas of uncertainty and recommendations for research. Ann Intern Med 2007;146:340-354.ArticlePubMed
  • 11. Pollock NR, Campos-Neto A, Kashino S, Napolitano D, Behar SM, Shin D, et al. Discordant QuantiFERON-TB Gold test results among US healthcare workers with increased risk of latent tuberculosis infection: a problem or solution? Infect Control Hosp Epidemiol 2008;29:878-886.ArticlePubMedPMC
  • 12. Talati NJ, Seybold U, Humphrey B, Aina A, Tapia J, Weinfurter P, et al. Poor concordance between interferon-gamma release assays and tuberculin skin tests in diagnosis of latent tuberculosis infection among HIV-infected individuals. BMC Infect Dis 2009;9:15.ArticlePubMedPMC
  • 13. Chkhartishvili N, Kempker RR, Dvali N, Abashidze L, Sharavdze L, Gabunia P, et al. Poor agreement between interferon-gamma release assays and the tuberculin skin test among HIV-infected individuals in the country of Georgia. BMC Infect Dis 2013;13:513.ArticlePubMedPMCPDF
  • 14. Connell TG, Ritz N, Paxton GA, Buttery JP, Curtis N, Ranganathan SC. A three-way comparison of tuberculin skin testing, QuantiFERON-TB gold and T-SPOT.TB in children. PLoS One 2008;3:e2624.ArticlePubMedPMC
  • 15. Swindells JE, Aliyu SH, Enoch DA, Abubakar I. Role of interferon-gamma release assays in healthcare workers. J Hosp Infect 2009;73:101-108.ArticlePubMed
  • 16. Szklo M, Nieto FJ. Epidemiology: beyond the basics. 3rd ed. Burlington: Jones & Bartlett Learning; 2014. p 338-340.
  • 17. Hashemi Shahri M, Fallah Ghajary A, Ansari Moghaddam A, Khadem Sameni F, Fayyaz Jahani F, Ahmadnezhad E. To compare the performance of Quanti-FERON with the tuberculin skin test for identifying latent tuberculosis infection. Iran J Epidemiol 2012;7:57-65 (Persian).
  • 18. Mirhaghani L, Nasehi M. National tuberculosis program in Iran. Tehran: Ministry of Health (Nashr-e Seda); 2002. p 15-20 (Persian).
  • 19. Khazaei HA, Rezaei N, Bagheri GR, Dankoub MA, Shahryari K, Tahai A, et al. Epidemiology of tuberculosis in the Southeastern Iran. Eur J Epidemiol 2005;20:879-883.ArticlePubMed
  • 20. Rafiee S, Besharat S, Jabbari A, Golalipour F, Nasermoaadeli A. Epidemiology of tuberculosis in northeast of Iran: a population-based study. Iran J Med Sci 2009;34:193-197.
  • 21. Sofian M, Zarinfar N, Mirzaee M, Nejad SA. Epidemiology of tuberculosis in Arak, Iran. Faslnamahi Kumish 2009;10:261-266 (Persian).
  • 22. Sim J, Wright CC. The kappa statistic in reliability studies: use, interpretation, and sample size requirements. Phys Ther 2005;85:257-268.ArticlePubMed
  • 23. Tripodi D, Brunet-Courtois B, Nael V, Audrain M, Chailleux E, Germaud P, et al. Evaluation of the tuberculin skin test and the interferon-gamma release assay for TB screening in French healthcare workers. J Occup Med Toxicol 2009;4:30.ArticlePubMedPMC
  • 24. Ozdemir D, Annakkaya AN, Tarhan G, Sencan I, Cesur S, Balbay O, et al. Comparison of the tuberculin skin test and the quantiferon test for latent Mycobacterium tuberculosis infections in health care workers in Turkey. Jpn J Infect Dis 2007;60:102-105.ArticlePubMed
  • 25. Jo KW, Hong Y, Park JS, Bae IG, Eom JS, Lee SR, et al. Prevalence of latent tuberculosis infection among health care workers in South Korea: a multicenter study. Tuberc Respir Dis (Seoul) 2013;75:18-24.ArticlePubMedPMC
  • 26. Dorman SE, Belknap R, Graviss EA, Reves R, Schluger N, Weinfurter P, et al. Interferon-γ release assays and tuberculin skin testing for diagnosis of latent tuberculosis infection in healthcare workers in the United States. Am J Respir Crit Care Med 2014;189:77-87.ArticlePubMed
  • 27. Doosti-Irani A, Ayubi E, Mostafavi E. Tuberculin and QuantiFERON-TB-Gold tests for latent tuberculosis: a meta-analysis. Occup Med (Lond) 2016;66:437-445.ArticlePubMed

Figure & Data

References

    Citations

    Citations to this article as recorded by  
    • Tuberculin test using Indian indigenous purified-protein derivative (PPD) shows only moderate agreement with international standard PPD
      Devasahayam J. Christopher, N. Priya, Deepa Shankar, Barney Isaac, Andrea DeLuca, Sonali Sarkar, Senbagavalli Prakash Babu, Prasanna Samuel, Adithya Cattamanchi, Amita Gupta, Jerrold Ellner, Sudha Srinivasan, Samyra Cox, Balamugesh Thangakunam
      Journal of Clinical Tuberculosis and Other Mycobacterial Diseases.2024; 34: 100404.     CrossRef
    • Performance of Current Diagnostic Tools in Detecting Latent Tuberculosis Among Healthcare Workers: A Systematic Review
      Aishwarya R, Maheshwary D, Leela KV, Vijay R Suriya, Kanya R
      Cureus.2024;[Epub]     CrossRef
    • Meta-analysis of latent tuberculosis in healthcare workers in Iran: a retrospective review
      NazaninZahra Sepehri, Seyed Mohammad Saghanezhad, Farshad Khoddami, Amin Arasteh, Marziyeh Delirakbariazar, Azad Khaledi
      Transactions of The Royal Society of Tropical Medicine and Hygiene.2021; 115(9): 965.     CrossRef
    • Risk of Occupational Latent Tuberculosis Infection among Health Personnel Measured by Interferon-Gamma Release Assays in Low Incidence Countries—A Systematic Review and Meta-Analysis
      Claudia Peters, Agnessa Kozak, Albert Nienhaus, Anja Schablon
      International Journal of Environmental Research and Public Health.2020; 17(2): 581.     CrossRef
    • Latent tuberculosis infection in healthcare workers in low- and middle-income countries: an updated systematic review
      Lika Apriani, Susan McAllister, Katrina Sharples, Bachti Alisjahbana, Rovina Ruslami, Philip C. Hill, Dick Menzies
      European Respiratory Journal.2019; 53(4): 1801789.     CrossRef
    • Latent Tuberculosis Infection among Healthcare Workers in Duhok Province: From Screening to Prophylactic Treatment
      Hind Bahzad Almufty, Ibtesam Salih Abdulrahman, Muayad Aghali Merza
      Tropical Medicine and Infectious Disease.2019; 4(2): 85.     CrossRef
    • Is latent tuberculosis infection challenging in Iranian health care workers? A systematic review and meta-analysis
      Mohammad Hossein YektaKooshali, Farahnaz Movahedzadeh, Ali Alavi Foumani, Hoda Sabati, Alireza Jafari, HASNAIN SEYED EHTESHAM
      PLOS ONE.2019; 14(10): e0223335.     CrossRef
    • Interferon-gamma release assay for the diagnosis of latent tuberculosis infection: A latent-class analysis
      Tan N. Doan, Damon P. Eisen, Morgan T. Rose, Andrew Slack, Grace Stearnes, Emma S. McBryde, Lei Gao
      PLOS ONE.2017; 12(11): e0188631.     CrossRef
    • Prevalence of latent tuberculosis infection among tuberculosis laboratory workers in Iran
      Mahshid Nasehi, Abdolrazagh Hashemi-Shahraki, Amin Doosti-Irani, Saeed Sharafi, Ehsan Mostafavi
      Epidemiology and Health.2016; 39: e2017002.     CrossRef

    Comparison of the tuberculin skin test and the QuantiFERON-TB Gold test in detecting latent tuberculosis in health care workers in Iran
    Comparison of the tuberculin skin test and the QuantiFERON-TB Gold test in detecting latent tuberculosis in health care workers in Iran
    TB lab staff
    Non-TB staff
    p-value Total
    n % n %
    Sex
     Male 100 56.50 47 70.15 0.05 147
     Female 77 43.50 20 29.85 97
    Age (yr)
     20-29 29 15.85 10 14.93 0.31 39
     30-39 86 46.99 26 38.81 112
     40-49 56 30.60 22 32.84 78
     ≥50 12 6.56 9 123.43 21
    Education level
     No high school diploma 17 9.60 12 17.91 0.001 29
     High school diploma 13 7.34 30 44.78 43
     Associate degree 59 33.33 8 11.94 67
     BS 74 41.81 16 23.88 90
     Master of science and above 14 7.91 1 1.49 15
    Job
     Lab position requiring a BS 85 48.02 - - 0.001 85
     Technician 60 33.90 - - 60
     Service personnel in lab 32 18.08 - - 32
     Administrative staff - - 42 62.69 42
     Finance staff - - 10 14.93 10
     Service personnel - - 15 22.39 15
    History of work (yr)
     0-4 62 35.03 14 20.90 0.001 76
     5-9 42 23.73 10 14.93 52
     10-14 36 20.34 12 17.91 48
     15-19 25 14.12 13 19.40 38
     ≥20 12 6.78 18 26.87 30
    History of BCG vaccination 159 89.83 50 74.63 209
    Variable QFT
    p-value TST
    p-value p-value1
    Prevalence 95% CI Prevalence 95% CI
    Sex
     Male 0.17 0.11, 0.23 0.92 0.20 0.13, 0.26 <0.05 0.46
     Female 0.18 0.10, 0.25 0.10 0.04, 0.16 0.22
    Age (yr)
     20-29 0.10 0.03, 0.24 0.13 0.03 0.00, 0.13 <0.05 0.16
     30-39 0.17 0.10, 0.25 0.16 0.10, 0.25 0.86
     40-49 0.23 0.14, 0.34 0.22 0.13, 0.33 0.85
     ≥50 0.05 0.00, 0.24 0.23 0.08, 0.47 0.07
    Education level
     No high school diploma 0.21 0.06, 0.36 0.68 0.28 0.11, 0.44 0.49 0.54
     High school diploma 0.09 0.00, 0.18 0.12 0.02, 0.21 0.50
     Associate degree 0.18 0.09, 0.27 0.16 0.07, 0.25 0.82
     BS 0.18 0.10, 0.26 0.13 0.06, 0.20 0.54
     Master of science and above 0.27 0.03, 0.50 0.20 0.01, 0.41 0.67
    Job group
     TB lab staff 0.19 0.12, 0.24 0.34 0.14 0.09, 0.19 0.20 0.25
     Non-TB staff 0.12 0.05, 0.22 0.21 0.11, 0.31 0.39
    Job
     Lab position requiring a BS 0.19 0.10, 0.27 0.78 0.14 0.07, 0.22 0.58 0.54
     Technician 0.17 0.07, 0.26 0.17 0.07, 0.26 0.81
     Service personnel in lab 0.22 0.07, 0.37 0.09 0.01, 0.20 0.17
     Administrative staff 0.14 0.04, 0.25 0.19 0.07, 0.31 0.56
     Finance staff - - 0.10 0.09, 0.30 0.31
     Service personnel 0.20 0.01, 0.41 0.33 0.09, 0.58 0.41
    History of work (yr)
     0-4 0.16 0.07, 0.24 0.42 0.11 0.03, 0.18 0.46 0.34
     5-9 0.15 0.05, 0.24 0.13 0.04, 0.22 0.78
     10-14 0.19 0.07, 0.30 0.21 0.09, 0.33 0.62
     15-19 0.16 0.04, 0.28 0.18 0.06, 0.31 0.56
     ≥20 0.23 0.08, 0.38 0.22 0.08, 0.39 1.00
    BCG vaccination
     No 0.26 0.11, 0.40 0.15 0.11 0.01, 0.22 0.42 0.12
     Yes 0.16 0.11, 0.21 0.17 0.12, 0.22 0.79
    Total 0.17 0.12, 0.21 0.16 0.11, 0.21 0.90
    Variable QF
    TST
    Unadjusted p-value Adjusted p-value Unadjusted p-value Adjusted p-value
    Sex
     Female 1.00 1.00 1.00 1.00
     Male 0.96 (0.49, 1.90) 0.89 0.98 (0.46, 2.07) 0.94 2.14 (0.99, 4.61) 0.05 1.75 (0.75, 4.08) 0.20
    Age 1.01 (0.97, 1.05) 0.69 0.99 (0.92, 1.06) 0.77 1.07 (1.02, 1.11) 0.003 1.07 (1.00, 1.15) 0.05
    Education Level
     No high school diploma 1.00 1.00 1.00 1.00
     High school diploma 0.39 (0.10, 1.54) 0.15 0.43 (0.10, 1.87) 0.26 0.35 (0.10, 1.19) 0.09 0.40 (0.10, 1.58) 0.19
     Associate degree 0.84 (0.28, 2.49) 0.70 0.81 (0.22, 2.95) 0.75 0.52 (0.18, 1.46) 0.21 1.27 (0.35, 4.55) 0.72
     Bachelor of science 0.83 (0.29, 2.36) 0.69 0.79 (0.22, 2.80) 0.71 0.40 (0.15, 1.12) 0.8 1.02 (0.28, 3.70) 0.98
     Master of science and above 1.40 (0.33, 5.97) 0.66 1.19 (0.23, 6.10) 0.84 0.66 (0.15, 2.95) 0.58 1.75 (0.30, 10.16) 0.53
    Job group
     Non-lab staff 1.00 1.00 1.00 1.00
     TB lab staff 1.48 (0.67, 3.28) 0.34 1.88 (0.67, 5.29) 0.23 0.62 (0.30, 1.26) 0.20 2.23 (0.11, 0.93) 0.04
    History of work (yr)
     0-4 1.00 1.00 1.00 1.00
     5-9 0.97 (0.37, 2.57) 0.95 1.00 (0.36, 2.74) 0.99 1.32 (0.45, 3.90) 0.61 1.07 (0.35, 3.30) 0.9
     10-14 1.23 (0.47, 3.18) 0.67 1.42 (0.49, 4.13) 0.52 2.24 (0.81, 6.14) 0.12 1.24 (0.41, 3.75) 0.71
     15-19 1.00 (0.34, 2.90) 1.00 1.30 (0.36, 4.61) 0.69 1.92 (0.64, 5.76) 0.25 0.77 (0.21, 2.85) 0.69
     ≥20 1.62 (0.57, 4.62) 0.36 2.64 (0.53, 13.09) 0.24 2.58 (0.84, 7.92) 0.09 0.54 (0.11, 2.68) 0.45
    Contact with TB patients
     No 1.00 1.00 1.00 1.00
     Yes 0.95 (0.49, 1.85) 0.87 0.73 (0.34, 1.56) 0.42 1.43 (0.72, 2.84) 0.31 1.70 (0.71, 4.05) 0.23
    BCG vaccination
     No 1.00 1.00 1.00 1.00
     Yes 0.54 (0.23, 1.26) 0.15 0.50 (0.21, 1.23) 0.13 1.56 (0.52, 4.70) 0.43 2.23 (0.67, 7.43) 0.19
    Group TST results (cut-off point of ≥ 10 mm) QFT results
    Total Agreement (%) Kappa (95%CI) p-value
    Negative Positive
    TB staff Negative 128 24 152 77.40 0.18 (0.00, 0.35) 0.008
    Positive 16 9 25
    Total 144 33 177
    Non-TB staff Negative 48 5 53 77.61 0.22 (-0.06, 0.50) 0.03
    Positive 10 4 14
    Total 58 9 67
    BCG vaccinated Negative 150 22 172 76.92 0.16 (-0.00, 0.32) 0.01
    Positive 26 10 36
    Total 176 32 208
    Non-BCG vaccinated Negative 25 7 32 75.00 0.18 (-0.16, 0.53) 0.11
    Positive 2 2 4
    Total 27 9 36
    All participants Negative 176 29 205 77.46 0.19 (0.04, 0.34) 0.001
    Positive 26 13 39
    Total 202 33 244
    Table 1. Demographic characteristics of the participants

    TB, tuberculosis; BS, bachelor of science; BCG, Bacillus Calmette-Guérin.

    Table 2. Comparison of the prevalence of LTBIs according to the QFT and TST

    LBTI, latent tuberculosis infection; TST, tuberculin skin test, QFT, QuantiFERON-TB Gold test; CI, confidence interval; TB, tuberculosis; BS, bachelor of science; BCG, Bacillus Calmette-Guérin.

    For the comparison of the TST and QFT in each subgroup.

    Table 3. Results of the TST and QFT according to probable risk factors

    Values are presented as odds ratio (95% confidence interval).

    TST, tuberculin skin test, QFT, QuantiFERON-TB Gold test; TB, tuberculosis; BCG, Bacillus Calmette-Guérin.

    Table 4. Overall agreement and kappa values between the QFT and TST results

    QFT, QuantiFERON-TB Gold test; TST, tuberculin skin test; CI, confidence interval; TB, tuberculosis; BCG, Bacillus Calmette-Guerin.


    Epidemiol Health : Epidemiology and Health
    TOP