Attenuated response to purified protein derivative in patients with rheumatoid arthritis: study in a population with a high prevalence of tuberculosis.

BACKGROUND: The purified protein derivative (PPD) skin test is the only widely used method which detects latent tuberculosis infection (LTBI) and is dependent on a normal T cell function. In rheumatoid arthritis (RA) the T cell function is altered, which may result in an inability to develop an adequate PPD reaction. OBJECTIVES: To evaluate the response to PPD in patients with RA and to compare it with that of control subjects. METHODS: 112 patients with RA and 96 healthy controls were studied. PPD 5 U was applied using the Mantoux method, and skin reaction was measured at 72 hours. The reaction was considered negative for PPD <5 mm. RESULTS: There were no significant differences in age, sex, history of bacille Calmette-Guerin vaccination, or tuberculosis contact between the two groups. The median size of the PPD induration in the patients with RA was significantly less than that in the control group (4.5 v 11.5 mm, p<0.01). 79 (70.6%) patients with RA compared with 25 (26%) of the control group had a negative reaction to PPD (p<0.01), a response not influenced by disease activity or duration of disease in the patients with RA. CONCLUSION: A PPD skin test is not an appropriate test for recognising LTBI in patients with RA in our population.

Validation of the preliminary criteria for the classification of catastrophic antiphospholipid syndrome.

OBJECTIVE: To describe the characteristics of patients with catastrophic antiphospholipid syndrome (APS) included in the International Registry of patients with this condition (CAPS registry) and to analyse the value of the recently proposed preliminary criteria for the classification of catastrophic APS. METHODS: A review of the first 220 patients included in the website based CAPS registry was undertaken and the preliminary criteria for their classification were tested; 175 unselected patients with systemic lupus erythematosus or APS, or both, acted as controls. RESULTS: The mean age of the patients was 38 (14) years (range 7 to 74), with a female preponderance (F/M, 153/67). The main clinical manifestations included renal involvement in 154 (70%), pulmonary in 146 (66%), cerebral in 133 (60%), cardiac in 115 (52%), and cutaneous in 104 (47%); 114 patients (52%) recovered after the catastrophic APS event (mortality 48%). Patients who received the combination of anticoagulation plus steroids plus plasma exchange or intravenous immunoglobulins had the best survival rate (63%, p = 0.09). Sufficient data could be analysed for application of the classification criteria in 176 patients. According to the preliminary criteria, 89 patients (51%) could be classified as having "definite" and 70 (40%) as having "probable" catastrophic APS, thus given a sensitivity of 90.3% with a specificity of 99.4%. Positive and negative predictive values were 99.4% and 91.1%, respectively. CONCLUSIONS: The preliminary criteria for the classification of catastrophic APS and the CAPS registry are useful tools for epidemiological studies.