0021-7557/00/76-02/115 Jornal de Pediatria - Vol. 76, Nº2, 2000 115 Jornal de Pediatria Copyright © 2000 by Sociedade Brasileira de Pediatria ORIGINAL ARTICLE Tuberculin test in the diagnosis of childhood tuberculosis: analysis of quantitative and qualitative features Henriqueta M.V. Oliveira,1 Clemax C. Sant’Anna2 Abstract Abstract: tuberculin test is an indirect method for diagnosing tuberculosis. It is important in the diagnosis of suspected childhood tuberculosis because children are often nonbacillary, or cannot produce sputum. Objective: to assess the accuracy of quantitative and qualitative features of tuberculin test in the diagnosis of childhood tuberculosis. Methods: evaluation of diagnostic tests; tuberculin tests with purified protein derivative RT-23 at two tuberculin units were carried out in 158 patients distributed in two groups: 101 Tb-negative and BCG- vaccinated children, and 57 tuberculous children diagnosed clinically, radiologically, and epidemiologically. Test results were analyzed quantitatively (Mantoux s test) and qualitatively (Koch- and Listeria-type reactions). Results: using cutoff for positivity at 10 mm in Mantoux s test, quantitative results indicated 85.9% of sensitivity, and 86.1% of specificity. Qualitative results (Koch-type reaction) indicated 77.2% of sensitivity and 98% of specificity. Conclusion: qualitative analysis of tuberculin test proved useful in the diagnosis of childhood tuberculosis in combination with Mantoux s test. J Pediatr (Rio J) 2000; 76(2): 115-8: tuberculosis - diagnosis, tuberculin test, child. Introduction Even though tuberculin was first discovered in 1890, it Taking this into consideration, tuberculin test with only started being used systematically and using different purified protein derivative (PPD) according to Mantoux’s techniques in 1907 and 1908.1,2 As a general rule, it is technique is used in the diagnosis of tuberculosis. In some known that individuals react to tuberculin injection when cases, it is also used in deciding medical procedures such as infected with Mycobacterium tuberculosis, with other in the chemoprophylaxis of children exposed to tuberculous mycobacteria, or, still, when previously vaccinated with patients. BCG. The importance of the tuberculin test for the diagnosis itself lies more in its negative predictive value, which is very high due to the epidemiological situation in Brazil, than in 1 1. Pediatrician and Neonatologist. Chief, Mental Health Service, Hospital its positive predictive value. Municipal Alexander Fleming (HMAF), Rio de Janeiro, RJ. 2. Associate Professor, School of Medicine, Department of Pediatrics, Studies of the prevalence of reaction to tuberculin tests Universidade Federal do Rio de Janeiro (UFRJ). allow assessing risk for infection in different communities, 115 116 Jornal de Pediatria - Vol. 76, Nº2, 2000 Tuberculin test in the diagnosis of childhood tuberculosis:... - Oliveira HMV et alii thus indicating the epidemiological importance of this test. We studied children from low-income families, of both Mass BCG vaccination campaigns have, to a certain extent, sexes, aged from 2 months to 12 years. Patients were made it difficult to assess prevalence of tuberculosis randomly selected and then divided into two study groups: infection. That is because reaction to tests may be caused group 1 - 57 inpatients who fulfilled criteria for diagnosis of both by M. tuberculosis infection and by previous BCG tuberculosis; group 2 - 101 children who were healthy, vaccination. There are, however, new methods for eutrophic, asymptomatic from a respiratory perspective, distinguishing between allergy produced by M. tuberculosis not presenting clinical or radiological evidence of and by other mycobacteria, including BCG.3 In this sense, tuberculosis nor history of tuberculosis infection, BCG- it was possible to assess risk for tuberculous infection in Rio vaccinated, and who were randomly selected at different de Janeiro4 and in São Paulo,5 respectively. outpatient clinics. Tuberculin test was carried out only after Moreover, studies have indicated that Listeria-type the obtainment of verbal consent from the parents or person reactions to tuberculin test are associated with protective responsible for the child. immunity of BCG; whereas Koch-type reactions are Patients were considered as a case of tuberculosis if the associated with ineffectiveness of BCG and tissue damaging following three diagnostic criteria were fulfilled: 6,7 hypersensitivity. a) suggestive clinical status, with evolution of fever for These findings have lead to the hypothesis that tuberculin over 15 days, with or without respiratory or extrapulmonary test with PPD RT-23 at two tuberculin units would allow symptoms, such as the indication of central nervous system quantitative assessment considering the size of induration, infection or peripheral adenomegaly with continuous and qualitative assessment considering the form of evolution for over 3 weeks; induration. Criteria used to classify reactions are presented b) chest X-ray presenting hilar or paratracheal in Table 1. adenomegaly, miliary hypopatency, or alveolar hypopatency The objective of our study is to determine the accuracy persisting for over 15 days with no response to antibiotic of quantitative and qualitative features of tuberculin test in therapy using drugs with no proven effect over M. the diagnosis of childhood tuberculosis. tuberculosis; c) reported contact with tuberculous adult patient. Our tuberculin tests were carried out by one of the authors (HMVO), who received previous training at the Table 1 - Criteria for qualitative classification of tuberculin Tuberculosis and Pneumology Institute, Universidade test Federal do Rio de Janeiro. The training consisted of the Characteristics Reaction type assessment of 32 tuberculin tests by two different examiners whose intra-class correlation coefficient was equal to 99.2%. Koch Listeria Tuberculin tests were administered to volar forearm, Induration Well-delineated Not well-delineated using PPD RT-23 tuberculin, tween 80, at 2 tuberculin units Consistency Hard Soft per ml, obtained from the Tuberculin Unit at Tuberculosis Painful Yes No and Pneumology Institute, Universidade Federal do Rio de Janeiro. Tests were assessed 72 hours after the administration of tuberculin according to Mantoux’s technique.1 We also carried out qualitative assessment related to the occurrence of Koch- and Listeria-type reactions according to Stanford et al.6,7 The smallest induration size considered for assessment was 4 mm. Patients and Methods Data were collected using specific forms and analyzed The study consisted of the evaluation of diagnostic tests using the Epi-info 6 statistical software. carried out prospectively from July 1986 until December 1989 at city, state, and federal public hospitals and healthcare units in the city of Rio de Janeiro, Brazil. This study included patients from the Unidade Auxiliar Results de Cuidados Primários de Saúde Vargem Grande, Group 1 included 57 patients aged 2 months to 12 years Jacarépaguá, and, in cases of hospital admission, from the (average = 35 months), and group 2 included 101 children following institutions: Hospital Geral de Nova Iguaçu, aged 3 months to 12 years (average = 35 months). Table 2 Hospital Municipal Jesus, Hospital Estadual São Sebastião, presents age distribution for both groups. We observed a Hospital Raphael de Paula Souza, and Instituto de predominance of children with less than 2 years of age (less Puericultura e Pediatria Martagão Gesteira (Universidade than 24 months) in our population: 29/57 (50.87%) in group Federal do Rio de Janeiro). 1 and 55/101 (54.45%) in group 2. Tuberculin test in the diagnosis of childhood tuberculosis:... - Oliveira HMV et alii Jornal de Pediatria - Vol. 76, Nº2, 2000 117 Table 2 - Distribution of children with and without tuberculosis (groups 1 and 2, respectively) according to age group Age groups Group 1 Group 2 (months) n % accumulated % n % accumulated % 02 – 11 16 28.08 28.08 38 37.63 37.63 12 – 23 13 22.81 50.89 17 16.83 54.46 24 – 35 8 14.03 64.92 10 9.90 64.36 36 – 47 3 5.26 70.81 6 5.94 70.30 48 – 59 7 12.28 82.46 5 4.95 75.25 60 – 71 2 3.51 85.97 6 5.94 81.19 72 - 83 2 3.51 89.48 7 6.93 88.12 84 – 95 4 7.02 96.50 7 6.93 95.05 96 – 107 2 1.98 97.03 108 – 119 1 1.75 98.25 2 1.98 99.01 120 – 131 132 - 143 144 - 155 1 1.75 100.00 1 0.99 100.00 BCG had been administered during the 1st month of age Table 4 - Distribution of children according to the presence of to 33 (57.89%) patients in group 1 and to all patients in tuberculosis and Koch-type reactions group 2. Koch phenomenon Tuberculosis Total Table 3 presents tuberculin test results for the 158 Yes No children assessed according to Mantoux’s technique. Results yielded sensitivity of 85.9% (49/57) and specificity of Positive 44 02 46 86.1% (87/101). Negative 13 99 112 Total 57 101 158 Table 3 - Distribution of children according to tuberculin test results and presence of tuberculosis Discussion Tuberculin test Tuberculosis Total After the assessment of tuberculin tests (induration size Yes No in millimeters), our findings yielded sensitivity and specificity lower than those found in the literature (around Reaction (> 10 mm) 49 14 63 90%).10 We believe that these results are coincidental, No reaction 8 87 95 since the indicated technical procedures were carefully Total 57 101 158 followed during testing. Table 5 - Distribution of children according to the presence of tuberculosis and Listeria-type reactions Listeria phenomenon Tuberculosis Total Table 4 presents distribution of children according to Yes No Koch-type reaction. Results yielded sensitivity of 77.2% (44/57) and specificity of 98.0% (99/101). Table 5 presents Positive 6 55 61 distribution according to Listeria-type reaction. Results Negative 51 46 97 yielded sensitivity of 12.3% (6/57) and specificity of 54.4% Total 57 101 158 (46/101). 118 Jornal de Pediatria - Vol. 76, Nº2, 2000 Tuberculin test in the diagnosis of childhood tuberculosis:..