Establishing a sample-to cut-off ratio for lab-diagnosis of hepatitis C virus in Indian context.

INTRODUCTION: Lab-diagnosis of hepatitis C virus (HCV) is based on detecting specific antibodies by enzyme immuno-assay (EIA) or chemiluminescence immuno-assay (CIA). Center for Disease Control reported that signal-to-cut-off (s/co) ratios in anti-HCV antibody tests like EIA/CIA can be used to predict the probable result of supplemental test; above a certain s/co value it is most likely to be true-HCV positive result and below that certain s/co it is most likely to be false-positive result. A prospective study was undertaken in patients in tertiary care setting for establishing this "certain" s/co value. MATERIALS AND METHODS: The study was carried out in consecutive patients requiring HCV testing for screening/diagnosis and medical management. These samples were tested for anti-HCV on CIA (VITROS(®) Anti-HCV assay, Ortho-Clinical Diagnostics, New Jersey) for calculating s/co value. The supplemental nucleic acid test used was polymerase chain reaction (PCR) (Abbott). PCR test results were used to define true negatives, false negatives, true positives, and false positives. Performance of different putative s/co ratios versus PCR was measured using sensitivity, specificity, positive predictive value and negative predictive value and most appropriate s/co was considered on basis of highest specificity at sensitivity of at least 95%. RESULTS: An s/co ratio of ≥6 worked out to be over 95% sensitive and almost 92% specific in 438 consecutive patient samples tested. CONCLUSION: The s/co ratio of six can be used for lab-diagnosis of HCV infection; those with s/co higher than six can be diagnosed to have HCV infection without any need for supplemental assays.

Stability of eosin-5'-maleimide dye used in flow cytometric analysis for red cell membrane disorders

BACKGROUND: The eosin-5'-maleimide (EMA) binding test using flow cytometry is a common method to measure reduced mean channel fluorescence (MCF) of EMA-labeled red blood cells (RBCs) from patients with red cell membrane disorders. The basic principle of the EMA-RBC binding test involves the covalent binding of EMA to lysine-430 on the first extracellular loop of band 3 protein. METHODS: In the present study, the MCF of EMA was analyzed for samples derived from 12 healthy volunteers (controls) to determine the stability (i.e., the percentage decrease in fluorescence) of EMA over a period of 1 year. RESULTS: Comparison of periodical MCF readings over time, that is, at 2-month intervals, showed that there were no significant changes in mean channel fluorescence for up to 6 months; however, there was a significant decrease in MCF at 8 months. CONCLUSION: For optimal dye utilization, EMA remained stable only for up to 6 months. Therefore, we recommend reconstitution of the dye every 6 months when implementing this test and storage at -80degrees C in dark conditions.

Use of blood components in critically ill patients in the medical intensive care unit of a tertiary care hospital.

BACKGROUND: The art of fluid administration and hemodynamic support is one of the most challenging aspects of treating critically ill patients. Transfusions of blood products continue to be an important technique for resuscitating patients in the intensive care settings. Concerns about the rate of inappropriate transfusion exist, particularly given the recognized risks of transfusions and the decreasing availability of donor blood. We investigated the current transfusion practice in the critically ill patients at our hospital. MATERIALS AND METHODS: A total of 1817 consecutive critically ill patients admitted between January 2006 and December 2006 were included in this retrospective study. The blood request forms of the patients were analyzed, and their pretransfusion investigations, indications for transfusions, etc. were studied. RESULTS: Nine hundred and eleven (50.1%) critically ill patients, comprising 71.6% males and 28.4% females, received blood/blood components. About 43.8% patients were administered packed red cells (PRC), 18.27% fresh frozen plasma (FFP) and 8.4% transfused platelets. Among those receiving PRC, 31.1% had a pretransfusion Hb below 7.5g%, 34.4% had Hb between 7.5 and 9g%, while 21.4% had Hb above 9g%. Among those receiving FFP, 14.5% had an international normalized ratio INR < 1.5, and 19% had a pretransfusion platelet count above 50,000/cumm. During the study, there were 7% of the patients who received red cells and FFP, 2% of the patients received red cells and platelets, 1% of the patients received platelets and FFP, and 5% of the patients had received all the three components, i.e., red cells, FFP and Platelets. The baseline investigations and/or clinical indications were not mentioned in 13.1% of patients receiving PRC, 57% receiving FFP and 49.7% receiving platelets. CONCLUSION: About 21.4% of PRC, 14.5% of FFP, and 19% of platelets were inappropriately indicated. Clinicians in our centre were conservative in keeping with recent transfusion guidelines. A significant number of blood request forms were still incomplete with baseline investigations not mentioned in the request forms.