Tuberculin Skin Test Size Research Articles

Psoriasis'te Biyolojik Tedavi Öncesi Latent Tüberküloz Enfeksiyonunun Değerlendirilmesi: Web Tabanlı Yorumlayıcı ile Yeni Bir Tanı Yaklaşımı

Purpose: The use of biological agents, particularly anti-TNF-alpha treatments, is associated with an elevated risk of tuberculosis (TB). Hence, a comprehensive assessment of latent tuberculosis infection (LTBI) before biologic therapies is imperative. The objective of this study was to evaluate the utility of an online tuberculin skin test (TST)/ interferon-γ release assay (IGRA) interpreter (OI-TST/IGRA) in assessing the risk of LTBI prior to initiating biological therapies in psoriasis patients.
 Materials and methods: 116 psoriasis patients who were previously evaluated for TB by a pulmonologist before being treated with a biologic agent were re-evaluated retrospectively with OI-TST/IGRA (tstin3d.com). Mean positive predictive value (PPV), mean annual risk of development of active tuberculosis (ARDATB), and mean cumulative risk of active tuberculosis (CRATB) values were calculated with OI-TST/IGRA and compared with previous results. Chi-square, Fisher-Freeman-Halton exact tests, Cohen's Kappa, and Mann-Whitney U-test were used in comparisons of groups. 
 Results: The PPV of the LTBI-positive group was significantly higher than the LTBI-negative group. The PPV, ARDATB and CRATB values of the TST size of >15 mm group were significantly higher than the TST size of 5-9 mm and TST size of 10-15 mm groups. The PPV, ARDATB, and CRATB values of the QuantiFERON-TB Gold In-tube test (QFT-GIT)-positive group were significantly higher than the QFT-GIT-negative group. And the same values of the chest X-ray (CXR)-positive group were significantly higher than the CXR-negative group. The PPV, ARDATB, and CRATB values were positively correlated with QFT-GIT and CXR results. In addition, the PPV was positively correlated with previous LTBI decisions and TSTs.
 Conclusion: OI-TST/IGRA in which many factors are questioned and PPV, ARDATB, and CRATB values are evaluated together, may be a valuable tool for assessing the risk of active TB in psoriasis patients and preventing overdiagnosis and unnecessary prophylaxis.

QuantiFERON-TB Gold Plus Test in Diagnostics of Latent Tuberculosis Infection in Children Aged 1-14 in a Country with a Low Tuberculosis Incidence.

The aim of the study was to evaluate the QuantiFERON-TB Gold Plus (QFT-Plus) test usability in the identification of latent tuberculosis infection (LTBI) in children and the determination of features associated with tuberculin skin test (TST) and QFT-Plus-positive results concerning LTBI. Two-hundred thirteen children aged 1–14 were screened for LTBI due to household contact with TB, suspected TB, or were qualified for biological therapy. The objective of this study was to evaluate the QFT-Plus affectivity as a diagnostic test in the absence of a gold standard (GS) test for the diagnosis of LTBI. The children were diagnosed with QFT-Plus, TST, and culture of TB. The QFT-Plus results were analyzed depending on the children’s age, TST size, and type. In children aged 1–4, the positive predictive value of QFT-Plus was 1, the negative predictive value was 0.94, QFT-Plus sensitivity was 75%, and specificity was 100%. It was observed that in children aged 5–14 years, the level of agreement decreased to the substantial, i.e., 87.2%. Moreover, the negative predictive value was 0.83. QFT-Plus sensitivity was 64%, and specificity was 100%. Statistical analysis of QFT-Plus and TST results showed substantial and almost perfect agreements. Our study suggests that QFT-Plus is helpful in a pediatric practice showing good sensitivity and specificity for LTBI. The BCG vaccine, infections, and concomitant morbidities do not affect QFT-Plus results.

DETERMINING THE NEED FOR ADDITIONAL TESTING WITH QUANTIFERON TB GOLD IN PATIENTS WITH POSITIVE TUBERCULIN SKIN TEST AND HISTORY OF BCG VACCINATION

SESSION TITLE: Chest Infections Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: October 18-21, 2020 PURPOSE: The tuberculin skin test (TST) has been the traditional method for the diagnosis of latent tuberculosis infection (LTBI) for many years. However recently Quantiferon TB gold (QFT) has become the definitive means of diagnosis of LTBI. However QFT is a more expensive test with needs for special equipment and skilled personnel. The purpose of this study is to determine which patient characteristics in patients with positive TST and previous history of BCG vaccination are associated with positive QFT so that we can eliminate the need for additional QTB testing in this patient population. We hypothesize that in patients with high risk features of TST induration diameter of 20mm and more, recent immigration to the USA, advanced age, country of origin with high endemicity, known exposure to active tuberculosis (TB) and smoking history, a positive TST likely expresses true exposure and less likely represents cross reactivity from positive BCG. METHODS: Retrospective chart review was done on adult patients who were referred to our pulmonary clinic with positive TST from January 2014 until December 2019. Patient data was extracted from medical records. The patients were divided into 2 groups. Group 1 consisted of true positive TST patients who had BCG vaccination and were positive for QFT. Group 2 consisted of false positive TST patients who had BCG vaccination but were negative for QFT. The 2 groups were compared with each other to determine if the high risk features were more prevalent in Group 1 compared to Group 2. RESULTS: In total 76 patients met the criteria for our study. Group 1 had 23 patients and Group 2 had 53 patients. The results showed that Group 1 had a higher prevalence of patients with advanced age (4.2%) compared to Group 2 (3%). Patients with exposure to active TB were more prevalent in Group 1(8.3%) compared to Group 2(5.3). However patients with smoking history were more prevalent in Group 2(11.1%) compared to Group 1(4.2%).The above differences were not statistically significant. Patients with TST induration of 20mm and more were more prevalent in Group 1 (60.9%) compared to Group 1(37.7%).The P value in this category alone was trending towards significance with a value of 0.06. Both Group 1 & 2 had equal distribution of patients with recent immigration (16.7%). Patients from Mexico constituted the single largest number of patients in both Group 1(54.2%) & in Group 2 ( 27.7%). CONCLUSIONS: High risk features of large TST size, recent immigration to USA, advanced age, country of origin with high endemicity, known exposure to active TB patients and smoking history does not indicate that positive TST expresses true exposure. Therefore QFT is still needed for definitive confirmation of LTBI. CLINICAL IMPLICATIONS: QFT is a superior testing study than TST for confirmation of LTBI. Hence patients with positive TST must undergo QFT testing to confirm the diagnosis of LTBI. DISCLOSURES: No relevant relationships by Antony Arumairaj, source=Web Response No relevant relationships by Imnett Habtes, source=Web Response No relevant relationships by Hansang Park, source=Web Response No relevant relationships by Fernando Quesada, source=Web Response

Determination of tuberculin skin test for isoniazid prophylaxis in BCG vaccinated children who are using anti-TNF agents for rheumatologic diseases.

The use of tumor necrosis factor inhibitors (anti-TNF) has a risk of activating latent tuberculosis infection (LTBI). This study was performed to investigate LTBI according to tuberculin skin test (TST) size and to determine the frequency of tuberculosis (TB) in bacillus Calmette-Guerin (BCG)-vaccinated children receiving anti-TNF treatment for rheumatological disease. The study consisted of 559 children. Information on demographics, anti-TNF agents, TST size, and isoniazid (INH) prophylaxis was recorded. Patients (n = 254) with TST size ≥5 mm were divided into three groups according to TST size and INH prophylaxis: group 1, TST size 5 to 9 mm and no INH prophylaxis; group 2, TST size 5 to 9 mm with INH prophylaxis; and group 3, TST size ≥10 mm with INH prophylaxis. The 559 patients comprised 314 (56.3%) females and 245 (43.6%) males; they had a mean age of 13.1 ± 4.1 years. The mean TST size in all patients was 4.2 ± 4.7 mm. Group 1 consisted of 76 (29.9%) patients, group 2 consisted of 88 (34.6%) patients, and group 3 consisted of 90 (35.4%) patients. The mean TST sizes for the three groups were 6.8 ± 3.1 mm, 7.2 ± 3.2 mm, and 13.9 ± 2.8 mm, respectively. New TB was diagnosed in only two (0.35%) patients. Both of them were in group 3. A TST size of ≥10 mm in BCG-vaccinated children receiving anti-TNF treatment may distinguish children at high risk for reactivation of LTBI.

Serum adenosine deaminase and tuberculin skin test in children with tuberculosis contact

Background: The tuberculin skin test (TST) is used in children who have been in contact with tuberculosis (TB). The test has limitations in terms of operator variability and the need for a second visit at 48–72 h for interpretation. Serum adenosine deaminase (ADA) was studied in adults and found to have a strong correlation with TST. Until now no data are available in the pediatric population. Objective: To examine the correlation between serum ADA and the TST in children who had been in contact with TB. Materials and Methods: A prospective study was conducted at Songklanagarind Hospital in southern Thailand among children aged 2–15 years with a history of contact TB between 2016 and 2018. Serum ADA was obtained before performing the TST. Children with active TB disease were excluded from the analysis. Results: Sixty-seven children were enrolled. The serum ADA ranged from 9.3–43 IU/L. The overall correlation between serum ADA and TST was poor (ρ = −0.03, P = 0.84). However, a subgroup analysis excluding 32 children with TST size 0 mm and a high variation of serum ADA (10–37.6 IU/L) found that in the remaining children, serum ADA and TST had a moderate correlation with statistical significance (ρ = 0.48, P = 0.004). Conclusions: The correlation between serum ADA and TST in contact TB pediatric patients was poor. The cause of low correlation was due to a high variability of serum ADA level in children who had no reaction to TST.

Experiences of Latent Tuberculosis Infection Treatment for the North Korean Refugees.

BackgroundTuberculosis (TB) is increasing in immigrants. We aimed to investigate the current status of latent tuberculosis infection (LTBI) treatment for North Korean Refugees (NKR) compared to South Koreans Contacts (SKC).MethodsTB close contacts in a closed facility of SKC and NKR who underwent LTBI screening in a settlement support center for NKR were analyzed retrospectively.ResultsAmong tuberculin skin test (TST) ≥10 mm (n=298) reactors, the males accounted for 72.2% in SKC (n=126) and 19.5% in NKR (n=172) (p<0.01). The mean age was higher in South Korea (42.8±9.9 years vs. 35.4±10.0 years, p<0.01). Additionally, the mean TST size was significantly bigger in NKR (17.39±3.9 mm vs. 16.57±4.2 mm, p=0.03). The LTBI treatments were initiated for all screened NKR, and LTBI completion rate was only 68.0%. However, in NKR, LTBI treatment completion rate was significantly increased by shorter 4R regimen (odds ratio [OR], 9.296; 95% confidence interval [CI], 4.159–20.774; p<0.01) and male (OR, 3.447; 95% CI, 1.191–9.974; p=0.02).ConclusionLTBI treatment compliance must be improved in NKR with a shorter regimen. In addition, a larger study regarding a focus on LTBI with easy access to related data for NKR should be conducted.

CD4 T-cell cytokine correlates of diagnostic tests for latent tuberculous infection in HIV-1-infected subjects

Public human immunodeficiency virus (HIV) clinic and tuberculosis (TB) clinics in Kampala, Uganda. To examine TB-specific CD4 T-cell single and polyfunctional cytokine correlates of clinical diagnostic tests for latent tuberculous infection (LTBI) in HIV-1-infected subjects. Thirty antiretroviral therapy-naïve HIV-1-infected adults without active TB disease underwent clinical tuberculin skin test (TST), interferon-gamma release assay (IGRA), and in vitro flow cytometry analysis on cells stimulated with purified protein derivative (PPD) and TB antigens early secreted antigenic target 6 + culture filtrate protein 10 (EC) for frequencies of interleukin (IL) 2, IL-17, interferon-gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) expressing cells. PPD-specific CD4 T-cell expression of TNF-α and IFN-γ was higher in the TST-positive than in the TST-negative group. EC-specific CD4 T-cell expression of TNF-α and IL-2 was higher in the TST+ group than in the TST- group. Expression of both PPD and EC-specific expression of IL-2, IFN-γ and TNF-α were greater in IGRA-positive than in IGRA-negative subjects. The TST+ group exhibited greater polyfunctionality than the TST- group. All cytokine combinations that contained TNF-α correlated strongly with TST size. While IL-2, IFN-γ and TNF-α correlate with clinical tests of LTBI, TNF-α is the dominant cytokine correlating with both TST size and magnitude of IGRA response.

Scar formation and tuberculin conversion following BCG vaccination in infants: A prospective cohort study.

Background:There is considerable variation in BCG scar failure rate on available data and correlation between BCG scar and tuberculin conversion remains controversial. Through this study we aimed to determine the scar failure rate and tuberculin conversion in term infants vaccinated with BCG within the first month.Materials and Methods:A prospective cohort study was conducted among 85 consecutive infants weighing >2 kg attending the immunization clinic of a medical college hospital. Fifteen subjects who could not complete the follow up were excluded. Total of 70 cases were analyzed. All babies were administered 0.1 ml of BCG and examined at 3 months (+1 week) for scar. Tuberculin test was done with 5TU PPD. An induration of >5 mm was considered positive. Statistical analysis was done using Microsoft Excel and SPSS-22.Results:Out of the 70 infants, 41 (58.6%) were males. Although majority (72.9%) of infants were vaccinated within 7 days, only 18 (25.7%) received BCG within 48 hours of birth. Sixty-four (91.4%) had a visible scar at 12 weeks post vaccination representing a scar failure rate of 8.6%. Tuberculin test was positive in 50 (71.4%). The mean ± s.d. for scar and tuberculin skin test (TST) reaction size was 4.93 ± 2.01 mm and 6.01 ± 3.22 mm, respectively. The association between scar formation and tuberculin positivity was highly significant (P < 0.001). There was significant correlation between scar size and TST size (r = 0.401, P = 0.001)Conclusions:Less than 10% of infants fail to develop a scar following BCG vaccination. There is good correlation between scar positivity and tuberculin conversion.

Risk factors for developing active tuberculosis after the treatment of latent tuberculosis in adults infected with human immunodeficiency virus.

Tuberculosis is the leading cause of death among adults infected with human immunodeficiency virus (HIV), and rates of tuberculosis remain high even after preventive therapy. Among 908 HIV-infected adults in a trial of preventive treatment, we found self-reported alcohol consumption, low baseline CD4 count, high baseline viral load, and tuberculin skin test size >15 mm as independent risk factors for incident tuberculosis.

Comparison of different methods and times for reading the tuberculin skin test

Current guidelines vary on the recommended method and time for measuring tuberculin skin test (TST) indurations. To evaluate the best time and method for assessing TST results and which purified protein derivative (PPD) to administer. Standard PPD (PPD-S) and PPD-RT23 were applied concurrently on each forearm in random order in 78 nurses. TST induration was measured at 48, 72 and 96 h by two nurses by palpation and a ruler, palpation and a Vernier caliper, ballpoint pen and a ruler or ballpoint pen and a Vernier caliper. TST differences were assessed using mixed-effects analysis. We also assessed the rate of false-positive/-negative results and the variability of the TST measurements. We performed 767 TST measurements. The adjusted mean TST size was larger with PPD-S than with PPD-RT23 (12.8 vs. 10.8 mm, P < 0.001), and at 72 h than at 48 h and 96 h (13.4 vs. 11.8 vs. 10.1 mm, P < 0.05). The smallest number of false results was observed with PPD-S, the ballpoint pen-ruler and at 72 h; palpation+ruler had the least variability at 72 h. The TST should ideally be performed with PPD-S and measured at 72 h with the ballpoint pen+ruler or palpation+ruler methods.

Characteristics of children with positive tuberculin skin test

The aim of the study was to define the characteristics of children with latent tuberculosis diagnosed with positive tuberculin skin test (TST) and evaluate potential risk factors in children with positive TST. Children followed with the diagnosis of latent tuberculosis infection were included in the study retrospectively. Demographic characteristics of patients including history of atopy, respiratory infections, family history of tuberculosis and atopy, number of BCG vaccinations, findings of physical examination and laboratory data were extracted from patient's file. Eighty-one children (51 male, 30 female) who had positive TST were retrospectively evaluated in the study. Mean age of the patients was 8.00 ± 4.00 years. Only 13 (16%) of the children had contact with a case who had active tuberculosis. It was shown that the age of the patients, number of BCG scars and BCG vaccination significantly affected TST reaction size. TST size was not affected with time passed after last dose of BCG vaccination, family history of tuberculosis, presence of TST positive case in the family, exposure to cigarette smoke, number of household family members and presence of respiratory allergic disease. The patient's age, numbers of BCG vaccination and BCG scars significantly affect TST results in childhood. This may cause difficulty in diagnosing latent tuberculosis infection and in decision of initiating prophylactic treatment. The results of this study may show that recently developed, more accurate and convenient in vitro tests that they have higher costs and require sophisticated laboratory, can be used to diagnose latent tuberculosis.

Tuberculin Skin-Test Reactions Are Unaffected by the Severity of Hyperendemic Intestinal Helminth Infections and Co-Infections

The tuberculin skin test (TST) quantifies cell-mediated immunity to tuberculosis antigens. Helminths suppress cell-mediated immunity, so we studied the effect of helminth infection and deworming on the TST in a randomized, double-blind, placebo-controlled study in an indigenous Amazon community (N = 195). Stool microscopy diagnosed helminths in 98% and co-infection with multiple species in 24% of study subjects. The TST was positive (> or = 10 mm) for 49%, and responses increased with age (P < 0.001), Bacille Calmette Guerin (BCG) vaccination (P = 0.01), and tuberculosis contact (P = 0.05). TST results had no association with helminth-egg concentrations, species, or co-infections (all P > 0.1). One month after deworming with albendazole (three daily 400-mg doses), helminths were reduced, but 63% remained infected with helminths. Albendazole did not cause a change in TST size (P = 0.8) or positivity (P = 0.9) relative to placebo. Thus, TST reactions were unaffected by albendazole therapy that partially cured intestinal helminth infections, and TST interpretation was unaffected by high-burden helminth infections and co-infection with multiple helminth species.

RANDOMIZED STUDY OF THE EFFECT OF TOPICAL ANESTHESIA ON TUBERCULIN SKIN TEST REACTION SIZE IN CHILDREN

Tuberculin skin test (TST) application in children can be eased by topical anesthesia, but no study has determined whether lidocaine-prilocaine mixture application modifies TST skin reactions. We compared TST performed with and without topical anesthesia in 46 children (range, 0.4-15.9 years), and found that topical lidocaine-prilocaine did not affect the TST size reaction. Topical lidocaine-prilocaine can be used for TST.

Cost-Effectiveness of LTBI Treatment for TB Contacts in British Columbia

Background Contacts of patients with active tuberculosis (“TB contacts”) with a tuberculin skin test (TST) size ≥5 mm are currently recommended treatment for latent TB infection (LTBI). Knowing the cost-effectiveness of LTBI therapy for specific TB contact subpopulations may improve the use of limited resources by reducing the treatment of persons at low TB risk. Objective To evaluate the cost-effectiveness of LTBI therapy for different TB contact populations defined by important risk factors, and to propose an optimal policy based on different recommendation for each subgroup of contacts. Methods A 6-year Markov decision analytic model simulating the quality-adjusted life years (QALYs), number of active TB cases prevented, and costs for hypothetical cohorts of Canadian TB contacts defined by TST size, age group (<10 y/o or above), ethnicity, closeness of contact, and Bacillus Calmette-Guérin (BCG) vaccination status. Results For the majority of subgroups, the current policy of preventive therapy in those with positive TST was the most cost-effective. Nevertheless, our analysis determined that LTBI treatment is not cost-effective in nonhousehold Canadian-born (nonaboriginal) or foreign-born contacts age ≥10 y/o. On the other hand, empirical treatment without screening of all non-BCG-vaccinated household contacts age <10 y/o appeared cost-effective. Such an optimal approach would result in an incremental net monetary benefit of $25 for each contact investigated for a willingness-to-pay of $50,000/QALY. Results were robust to several alternative assumptions considered in sensitivity analyses. Conclusions The current practice of LTBI treatment for TB contacts with a TST size ≥5 mm is cost-effective. A customized approach based on excluding low risk groups from screening and providing treatment to high risk contacts without screening could improve the performance of the program.

Hygiene hypothesis, allergy and BCG: a dirty mix?

Hygiene hypothesis, allergy and BCG: a dirty mix?

Comparison of tuberculin skin test response after three modalities of neonatal BCG vaccination

The aim of this study was to determine the tuberculin skin test (TST) response to three different BCG modalities [0.1 ml Tokyo (n=104), 0.05 ml Pasteur-Mérieux (n=137) and 0.1 ml Pasteur-Mérieux (n=100)] in a cohort of healthy newborns 5 months after vaccination at birth in Santiago, Chile. Among the 341 infants, 91.2% had a response to TST, and the mean+/-SD TST reaction size was significantly larger in infants receiving the Tokyo strain than in those receiving the 0.05 ml or 0.1 ml Pasteur-Mérieux strains (4.4+/-2.0, 3.5+/-1.3 and 3.1+/-1.4 mm, respectively; P<0.0001). The mean+/-SD of the BCG scar size was significantly lower in infants vaccinated with the Tokyo strain than in those vaccinated with the 0.1 ml Pasteur-Mérieux strain (3.9+/-1.2 vs. 4.3+/-1.1 mm; P=0.03) and no significant difference was found between infants receiving the Tokyo strain and the 0.05 ml Pasteur-Mérieux strain. However, the differences in TST size induced by diverse BCG vaccination modalities may not reflect the quality of the immunologically induced response in terms of TB protection.

Mycobacterium tuberculosis infection may protect against allergy in a tuberculosis endemic area

Epidemiological studies have shown an inverse relation of mycobacterial infection and the frequency of allergic diseases and asthma. Recent evidence suggests that allergic inflammation may be inhibited in the presence of chronic and persistent infections, such as that by Mycobacterium tuberculosis (MTB). The relation of tuberculin skin test (TST) size, an accepted marker of MTB infection and the frequency of allergic disease symptoms has not been reported from an area where MTB infection is endemic. To investigate the association of TST and allergic disease symptoms, in children living in a tuberculosis (TB) endemic area. In this cross-sectional study, 841 children aged 6-14 years from randomly selected household addresses in two poor communities of Cape Town, South Africa, were investigated with TST and standardized International Study on Asthma and Allergies in Childhood-based questionnaire on allergic disease symptoms. Children with positive TST (> or =10 mm) were significantly less likely to have allergic disease symptoms, in particular allergic rhinitis (AR) (adjusted odds ratio 0.43; 95% confidence interval 0.24-0.79) than those with negative TST. This association remained significant after adjusting for possible confounders and correcting for the effect of clustering (>1 child per household address) in the sample. There was a significant inverse linear trend in the relation of TST size in millimetre and the frequency of allergic disease symptoms, in particular AR (P<0.001). These results of inverse association of strong TST reaction and allergic disease symptoms in children from a TB endemic area are in support of the hypotheses that allergic inflammation may be inhibited by chronic infections, such as MTB.

A prospective study of bacillus Calmette-Guérin scar formation and tuberculin skin test reactivity in infants in Lima, Peru.

To determine the sensitivity of the bacillus Calmette-Guérin (BCG) scar as an indicator of previous vaccination and to ascertain the tuberculin skin test (TST) response in infancy after vaccination in a community from an area hyperendemic for tuberculosis (TB). In a birth cohort of healthy term infants from Lima, Peru, a single dose of BCG vaccine was administered within the first month of life. Scar formation was assessed biweekly during the first 6 months and again at 3 years after vaccination. TST response was evaluated 6 months after vaccination. Six months after vaccination, 99% (68) of the newborns exhibited a BCG scar (>2 mm). Scar size did not differ by sex, birth weight, age at vaccination, or nutritional status in the first 2 months. Eighty percent of the participants were found 3 years after vaccination, and all of them had a BCG scar. Mean TST reaction size 6 months after vaccination was 2.9 +/- 0.3 mm. No association was found between sex or age at BCG vaccination and TST size. Only 3 children had a TST >10 mm, and the 3 had a TB contact at home. The BCG scar was a sensitive indicator of vaccination status up to 3 years after the administration of the vaccine in the first month of life. Although nearly a quarter of the children had a TST response >5 mm 6 months after vaccination, TST reactions >10 mm did not occur in the absence of exposure to a person with tuberculosis. A cutoff of 10 mm should be used for disease control purposes in people who are born in countries where TB is endemic.

Screening and treatment for latent tuberculosis infection among asylum seekers entering Switzerland.

To evaluate the compliance of doctors and patients with the current recommendations for screening and preventive treatment of immigrants with a positive tuberculin skin test (TST) suggestive of latent tuberculosis infection (LTBI). Retrospective cohort study of all asylum seekers entering Switzerland between 1 January 1993 and 31 December 1993 and assigned to the cantons of Aargau, Fribourg, Geneva, Neuchâtel, Valais and Vaud, who underwent a TST at the border. The medical documents of all individuals with a TST size suggestive of LTBI (> or = 10 mm in children <15 years, > or = 18 mm in young adults aged 15-25 years) were reviewed for final diagnosis, therapeutic decision, compliance with treatment if prescribed, and notification for tuberculosis within the next 3 years. Among 2515 asylum seekers, 172 had a positive TST suggestive of LTBI. The documents of 93 persons were available. The final diagnosis was LTBI in 71 cases, possible tuberculosis in 10 cases, an effect of BCG immunisation in 10 cases, and other diagnoses in 2 cases. Among 82 individuals with normal chest X-ray or no radiological examination, only 37 (46%) received a preventive treatment and one a full course of antituberculosis drugs. Among 11 persons with an abnormal chest X-ray, 2 received a full course of antituberculosis drugs, 7 a preventive therapy and 2 had no treatment prescribed. Among the 44 subjects in whom a preventive treatment was prescribed, 30 adhered to the treatment regimen. One case (without prescribed treatment) was notified for tuberculosis two years after entry. Compliance of doctors and patients with current recommendations for examination and treatment of immigrants with a TST suggestive of LTBI is unsatisfactory. New guidelines are needed to provide a clearer definition of the indications and explain the benefits of treating LTBI.

Screening and treatment for latent tuberculosis infection among asylum seekers entering Switzerland.

To evaluate the compliance of doctors and patients with the current recommendations for screening and preventive treatment of immigrants with a positive tuberculin skin test (TST) suggestive of latent tuberculosis infection (LTBI). Retrospective cohort study of all asylum seekers entering Switzerland between 1 January 1993 and 31 December 1993 and assigned to the cantons of Aargau, Fribourg, Geneva, Neuchâtel, Valais and Vaud, who underwent a TST at the border. The medical documents of all individuals with a TST size suggestive of LTBI (> or = 10 mm in children <15 years, > or = 18 mm in young adults aged 15-25 years) were reviewed for final diagnosis, therapeutic decision, compliance with treatment if prescribed, and notification for tuberculosis within the next 3 years. Among 2515 asylum seekers, 172 had a positive TST suggestive of LTBI. The documents of 93 persons were available. The final diagnosis was LTBI in 71 cases, possible tuberculosis in 10 cases, an effect of BCG immunisation in 10 cases, and other diagnoses in 2 cases. Among 82 individuals with normal chest X-ray or no radiological examination, only 37 (46%) received a preventive treatment and one a full course of antituberculosis drugs. Among 11 persons with an abnormal chest X-ray, 2 received a full course of antituberculosis drugs, 7 a preventive therapy and 2 had no treatment prescribed. Among the 44 subjects in whom a preventive treatment was prescribed, 30 adhered to the treatment regimen. One case (without prescribed treatment) was notified for tuberculosis two years after entry. Compliance of doctors and patients with current recommendations for examination and treatment of immigrants with a TST suggestive of LTBI is unsatisfactory. New guidelines are needed to provide a clearer definition of the indications and explain the benefits of treating LTBI.