Comparison between in vivo measurement of the Montenegro skin test and paper recording

Montenegro skin test and paper recording The Montenegro skin test (MST) is the main complementary exam for the diagnosis of American cutaneous leishmaniasis (ACL) and evaluates the delayed hypersensitivity reaction to Leishmania antigens. The antigen is injected intradermally into the forearm and, after 48 hours, the presence of local induration is evaluated. Induration diameters of 5 mm or more are considered to be positive. Sokal observed that some professionals encounter difficulties during the tuberculin test in delimiting the margin of the induration by palpation. Additionally, discordance in the reading was observed between trained professionals. The author therefore developed the ballpoint pen technique, in which a line is drawn with a ballpoint pen from a point about 2 cm away from the indurated area toward its center until noting resistance when the margin of the induration is reached. Reading of the reaction became possible after the introduction of the stamping technique in which paper soaked in 70% alcohol is pressed on the site of the induration.. However, no studies are available in the literature comparing measurements performed in vivo at the site of application of the test and those recorded on paper. A total of 154 patients with a clinical suspicion of ACL seen at Instituto de Pesquisa Clínica Evandro Chagas, Fiocruz, were submitted to the MST. After 48 hours, in vivo reading was performed by the ballpoint pen technique (Fig. 1). In addition, a paper recording was obtained from each reaction and stored for subsequent measurement by another professional. Both the in vivo and paper measurements were performed within the demarcation line with a millimeter-graded ruler. The results of the two measures were compared by the kappa test using the Epi-Info 6 program. A total of 143 results were concordant and 11 were discordant in terms of a positive or negative MST. The kappa index of agreement between the two measurements was 0.83%, with an approximate standard error of 0.048 and P < 0.0001 (Table 1). A difference of 1 mm between readings was observed in 59 patients, and differences of 2–6 mm were observed in 18. However, the paper reading resulted in a negative test (diameter <5 mm) in only 11 patients. These results suggest that the paper recording might be used as an alternative to the direct reading, despite the 11 discordant patients. In addition, the paper with the tracing provides a record and documentation of the exam and may serve as a quality control for the evaluation of services standardizing the technique.