RESUMEN

OBJECTIVE: There are various methods for anti-dsDNA detection. Crithidia luciliae indirect immunofluorescence test (CLIFT) and enzyme immunoassay (EIA) are the most commonly used at present. A number of CLIFT and EIA kits are commercially available. The objective of the present study was to evaluate the diagnostic performance of three commercial CLIFT kits, two commercial EIA kits, and their combinations for anti-dsDNA detection. MATERIAL AND METHOD: One hundred thirty nine sera sent for anti-dsDNA testing were investigated. Three commercial CLIFT kits (kit C1, C2, and C3) and two commercial EIA kits (kit E1 and E2) were evaluated. Sensitivities and specificities were calculated. The gold standard methods were the consensus results of all five kits, together with the clinical diagnosis when the results of five kits were discrepant. RESULTS: Of 139 sera investigated, 94 (67.6%) sera showed concordant results for all five kits and 45 (32.4%) sera showed discordant results. Thirty-five of those 45 patients (77.7%) were diagnosed as SLE. Sensitivities and specificities of the kits were as follows, Cl 82.1% and 94%, C2 46.4% and 100%, C3 78.6% and 98.8%, E1 71.4% and 94%, and E2 75% and 93.8%, respectively. Kit C3 yielded the maximum sum of sensitivity and specificity (177.4%). Sensitivities and specificities of the combinations of CLIFT and EIA kits were as follows, C1 + E1 89.3% and 90.4%, C1 + E2 98.2% and 87.9%, C2 + E1 73.2% and 94%, C2 + E2 82.1% and 92.8%, C3 + E1 85.7% and 94%, and C3 + E2 94.6% and 91.6%, respectively. The combination of kit C3 and E2 yielded the maximum sum of sensitivity and specificity (186.2%). CONCLUSION: Kit C3 was the assay of choice for anti-dsDNA detection. EIA kits yielded lower sensitivities and specificities than two of three CLIFT kits. Therefore, they should not be used as the first assay for anti-dsDNA screening. When CLIFT and EIA assays were combined, sensitivities were increased Kit E2 helped CLIFT kits to detect more SLE cases than E1.

Asunto(s)

Asunto(s)

RESUMEN

BACKGROUND: Anti-Ro antibody may directly react against either Ro60 or Ro52 or both antigens. To be more applicable for routine laboratory practice, the specific antigen type for antibody detection should be identified before test application. OBJECTIVE: Investigate the prevalence of 60 kDa and 52 kDa Ro/SS-A antibodies in Thai patients' sera in Siriraj Hospital. MATERIAL AND METHOD: Specimens for anti-Ro were requested between June and December 2005. They were tested with EUROLINE test kit for prevalence determination. The principle of the test is a qualitative in-vitro-assay that contains test strips coated with parallel lines of 14 highly purified antigens. Of 84 specimens requested for anti-Ro antibody, 76 were collected and tested with the EUROLINE test kits and eight were excluded due to inadequacy. RESULTS: The prevalence of anti-Ro60 and anti-Ro52 of all sera tested for anti-Ro by EUROLINE test kit were 30% (95% CI: 20-40%) and 26% (95% CI: 16-36%), respectively; and, those in anti-Ro positive Thai sera were 82% (95% CI: 68-96%) and 71% (95% CI: 54-88%), respectively. The prevalence of anti-Ro52 alone in anti-Ro positive Thai sera and all specimens requested for anti-Ro was about 18% (95% CI: 4-32%) and 7% (95% CI: 1-13%), respectively. The agreement and Kappa value between the two methods were 0.9 and 0.77, respectively. The study suggests that the test for anti-Ro detection should provide both Ro 60 and Ro 52 antigens. CONCLUSION: The prevalence of both anti-Ro 60 and anti-Ro 52 were quite common, therefore, the test for this specific antibody should provide both antigens for antibody detection.

Asunto(s)

RESUMEN

BACKGROUND: To reduce human errors and subjective interpretation, automation is currently a trend. However, replacing any tests with automation must first be validated. OBJECTIVE: Evaluate the EIA tests performance characteristics of three commercially available enzyme immunoassays; Enzygnost Syphilis (Dade Behring Ltd), Syphilis EIA 480 (Newmarket Laboratory Ltd) and ICE* Syphilis (Abbott Murex). MATERIAL AND METHOD: Three thousand and fifty-five serum samples were obtained from all workers who came for physical check ups before working abroad at the physical check-up unit of the out- patient department at Siriraj Hospital between February and August, 2001. Serum specimens known to be positive with VDRL and TPHA or FTA-ABS tests were included in the present study. RESULTS: Of all the samples, 2953 were from workers who came for physical check ups; 102 were selected from known specimens positive with the Venereal Disease Research Laboratory test (VDRL) and Treponema Pallidum Hemagglutination Assay (TPHA) or Fluorescent Treponemal Antibody ABSorption (FTA-ABS) test. A true positive result was determined when the sample was reactive either with two out of three enzyme immunoassays and TPHA or FTA-ABS, or both TPHA and FTA-ABS. A true negative result was determined when the aforementioned were absent. The sensitivity and specificity of Enzygnost Syphilis, Syphilis EIA 480 and ICE* Syphilis were 100% and 97.89%, 100% and 99.59%, and 99.1% and 99.76%, respectively. The results suggest that the specificity of Enzygnost Syphilis is the lowest among these three enzyme immunoassays; the price is also the cheapest. The decision to replace an existing test depends not only on the performance characteristics but also on other factors such as cost effectiveness, turnaround time, instrument maintenance, etc. The present study shows performance characteristics, whereas an economic evaluation is only briefly mentioned regarding a hospital's decision in making test selection. CONCLUSION: Among the three commercial kits, the specificity of Enzygnost Syphilis was the lowest. However, the replacement of any existing test depends greatly on the purpose of the individual laboratory whereas performance characteristics will provide us with an appropriate economic evaluation.

Asunto(s)

RESUMEN

OBJECTIVE: The aim of this study was to determine the validity of pleural fluid C-reactive protein (CRP) concentrations and/or pleural fluid to serum CRP ratio for differentiating tuberculous pleuritis (TBP) from malignant pleural effusion (MPE) in patients presenting with lymphocytic exudative pleural effusions. METHODOLOGY: A cross-sectional study was conducted on 161 patients with pleural effusion who underwent diagnostic evaluation at Siriraj Hospital, Bangkok, Thailand, between April 2001 and March 2002. The complete biochemical analysis of pleural fluid, cultures of pleural fluid, and pathological examinations of pleural fluid and pleural tissue were performed. The CRP concentrations were then measured in stored sera and pleural fluid samples from patients with a lymphocytic exudative pleural effusion and with a definite diagnosis. RESULTS: Among the 148 patients with lymphocytic exudative pleural effusions, 55 were diagnosed with TBP, 60 with MPE, and 33 with non-specific pleuritis. Pleural fluid and serum CRP levels were significantly higher in the TBP group than in the MPE group (54.58 +/- 4.50 mg/L and 106.93 +/- 9.54 mg/L vs 12.66 +/- 3.52 mg/L and 49.66 +/- 8.84 mg/L, respectively, P < 0.001). The ratio of pleural fluid to serum CRP was significantly higher in the TBP group than in the MPE group (0.52 +/- 0.18 vs 0.30 +/- 0.16, P < 0.001). The optimum cut-off value for pleural fluid CRP level of > or =30 mg/dL had a sensitivity of 72% with 93% specificity, and the pleural fluid to serum CRP ratio cut-off value of 0.45 had a sensitivity of 60% with 89% specificity. A correlation between serum and pleural fluid CRP levels was observed in TBP patients but not in MPE patients. CONCLUSION: In patients presenting with lymphocytic exudative pleural effusion, a simple marker of raised pleural fluid CRP level may be helpful in discriminating between TBP and MPE.

Asunto(s)