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Revista Brasileira de Reumatologia
On-line version ISSN 1809-4570
MARQUES, Cláudia Diniz Lopes et al. Attenuated response to PPD in the diagnosis of latent tuberculosis infection in patients with rheumatoid arthritis. Rev. Bras. Reumatol. [online]. 2009, vol.49, n.2, pp.121-125. ISSN 1809-4570. http://dx.doi.org/10.1590/S0482-50042009000200004.
INTRODUCTION: With the introduction of Tumor Necrosis Factor Inhibitors (anti-TNFs) into rheumatological practice, it has become obligatory to identify cases of latent tuberculosis infection (LTBI) prior to the start of treatment, using PPD, chest radiography and clinical history of tuberculosis contact. Patients with Rheumatoid Arthritis (RA) have an abnormality of the cellular immune function, characterized by decreasing responsiveness of peripheral mononuclear cells (T Reg lymphocytes), leading to a loss in delayed hypersensitivity, which is fundamental for the recognition of antigens, such as PPD. OBJECTIVES: The purpose of our study was to evaluate the response to PPD in patients with RA, compared with healthy people, in an area where tuberculosis is endemic, as is the state of Pernambuco. METHODOLOGY: We studied 96 patients, 48 with RA and 48 healthy subjects, most of them females. All patients were given an interdermic injection of 0.1 mL PPD RT-23. The reading of the PPD result was carried out 72 hours after application, by way of palpation of maximum transverse diameter of induration, and the result was expressed in millimeters. RESULTS:In the RA group, the average time of diagnosis was 10.2 years, the average dosage of methotrexate was 15.5 mg / week, the average dosage of prednisone 12.7 mg / day and the average activity of the disease, measured using CDAI, was 30.4. In the healthy subjects group there was a greater number of positive PPD results (33.3%) when compared with the results for the RA group (14.6%), with a statistically significant difference (p = 0.034). CONCLUSION:The performance of PPB in LTBI diagnosis is poor in patients with RA. These results suggest that more careful screening needs to be undertaken before treatment with an anti-TNF drug.
Keywords : rheumatoid arthritis; PPD; latent tuberculosis.