[Guideline for interpretation and report of the antibody to hepatitis C virus. Grupo de Desarrollo de la Guía ]. / Guía de interpretación y reporte del anticuerpo a hepatitis C.

Patients with hepatitis C virus (HCV) infection are detected by testing for the presence of antibodies to HCV (Anti-HCV). A positive Anti-HCV test represents a true positive result only in a variable proportion of subjects (35 to 95%). The qualitative interpretation as positive or negative Anti-HCV report is associated with a general lack of understanding regarding the interpretation of results, when more specific testing should be performed, and which tests should be considered for this purpose. Therefore, a substantial variation in supplemental testing practices exists among laboratories and physicians. This guideline was developed on the basis of the best available evidence to classify positive antibody in two (low and high) or three levels (very low, low and high) according to the signal to cutoff (S/CO) ratio: the very low level of the Anti-HCV identifies false-positive results and further diagnostic testing is not necessary. The low antibody level is frequently related with false-positive results and testing with Immunoblot is recommended; only Immunoblot-positive subjects require HCV RNA testing because of a low possibility of being viremic. The high Anti-HCV level is an accurate serological marker for predicting viremia and denotes the need of routine HCV RNA testing in order to efficiently confirm hepatitis C. Cost-effectiveness analysis, based on the Anti-HCV level, recommends the use of the two or three-levels to choose the confirmatory test of positive antibody. This approach can be implemented without increasing test costs because the S/CO ratio is automatically generated in most laboratory analyzers and would provide health care professionals with useful information for counseling and evaluating patients, to eliminate unwarranted notifications in cases of false antibody reactivity, and correctly identifying those Anti-HCV-positive patients who are infected and need antiviral treatment. The written report should include the antibody level (S/CO ratio), the type of the immunoassay applied and interpretation guideline. Anti-HCV testing is performed in multiple settings including blood banks or health department facilities; adoption of this Guideline for interpretation and report of the antibody to hepatitis C virus by laboratories and its implementation by clinicians will improve the accuracy for interpreting antibody result to determine the next step on hepatitis C diagnosis.

[Nosocomial transmission of hepatitis C associated with anesthesia procedures: a case-control study]. / Transmisión nosocomial de la hepatitis C asociada a procedimientos anestésicos: un estudio de casos y controles.

OBJECTIVE: Nosocomial transmission of hepatitis C virus (HCV) infection had been related with anesthesia procedures. The study aim was to measure the association between anesthesia procedures in cases with previous surgery and HCV infection. MATERIAL AND METHODS: In a case-control study were included subjects that attended to the Central Blood Bank of the West Medical National Center, Mexican Institute of the Social Security in Guadalajara, Jalisco between july 2005 and september 2007. Cases were patients with positive hepatitis C antibody (anti-HCV) confirmed by recombinant immunoblot assay (RIBA) and/or nucleic acid test (HCV RNA); the control group was blood donors with negative antibody. An exhaustive questionnaire about risk factors for hepatitis C, was applied. The risk of HCV infection was determined with the Odds Ratio (OR) and multivariate analysis was made by logistic regression. RESULTS: We included 362 subjects, 211 cases and 151 controls; in 70 (33.2%) cases were found significant association between the anesthesia procedures and HCV infection in patients with previous surgery (OR adjusted 2.44, CI 95% 1.44 - 4.11) CONCLUSION: This is the first study in México that demonstrate association between history of anesthesia procedures and HCV infection in cases with previous surgery.

Transmisión nosocomial de la hepatitis C asociada a procedimientos anestésicos: un estudio de casos y controles

OBJETIVO: Medir la asociación entre el antecedente de procedimientos anestésicos y el riesgo de infección por el virus de la hepatitis C (VHC) en pacientes con cirugía previa. MATERIAL Y MÉTODOS: Diseño de casos y controles; los casos fueron pacientes con anticuerpo (anti-VHC) positivo confirmado por RIBA y/o RNA VHC y los controles fueron sujetos con el anti-VHC negativo. El riesgo de infección se estimó por razón de momios (RM) y análisis multivariado con regresión logística. RESULTADOS: Se incluyeron 362 sujetos, 211 casos y 151 controles; en 70 casos (33.2 por ciento), con cirugía previa, los procedimientos anestésicos se identificaron como único factor de riesgo significativo para la infección por el VHC (RM ajustada 2.44, IC 95 por ciento 1.44 - 4.11). CONCLUSIONES: Este es el primer estudio en México que demuestra asociación de riesgo significativa con el antecedente de procedimientos anestésicos por cirugía previa, en uno de cada tres enfermos con hepatitis C.

OBJECTIVE: Nosocomial transmission of hepatitis C virus (HCV) infection had been related with anesthesia procedures. The study aim was to measure the association between anesthesia procedures in cases with previous surgery and HCV infection. MATERIAL AND METHODS: In a case-control study were included subjects that attended to the Central Blood Bank of the West Medical National Center, Mexican Institute of the Social Security in Guadalajara, Jalisco between july 2005 and september 2007. Cases were patients with positive hepatitis C antibody (anti-HCV) confirmed by recombinant immunoblot assay (RIBA) and/or nucleic acid test (HCV RNA); the control group was blood donors with negative antibody. An exhaustive questionnaire about risk factors for hepatitis C, was applied. The risk of HCV infection was determined with the Odds Ratio (OR) and multivariate analysis was made by logistic regression. RESULTS: We included 362 subjects, 211 cases and 151 controls; in 70 (33.2 percent) cases were found significant association between the anesthesia procedures and HCV infection in patients with previous surgery (OR adjusted 2.44, CI 95 percent 1.44 - 4.11) CONCLUSION: This is the first study in México that demonstrate association between history of anesthesia procedures and HCV infection in cases with previous surgery.

High antibody level: an accurate serologic marker of viremia in asymptomatic people with hepatitis C infection.

BACKGROUND: The screening and diagnosis of hepatitis C virus (HCV) infection is initiated by testing for antibody to HCV (anti-HCV). A positive anti-HCV test in blood donors represents ongoing infection in only a variable proportion of individuals. Because a high anti-HCV level has been associated with viremia, a study was conducted to determine whether a high antibody level is an accurate serologic marker for viremia in asymptomatic anti-HCV-positive persons. STUDY DESIGN AND METHODS: In a diagnostic test study, we included 856 anti-HCV-positive blood donors in a blood bank at Guadalajara, Jalisco, Mexico, between 2002 and 2007. A third-generation amplified chemiluminescence assay (ChLIA HCV) was used to detect anti-HCV. A positive result of the qualitative nucleic acid test (HCV RNA) was considered the gold standard for viremia. RESULTS: By receiver operating characteristic analysis, the signal-to-cutoff (S/CO) ratio of 20 or more was chosen as optimal to identify viremia and so was defined as high anti-HCV level. There was a significant difference in the proportion of viremia between subjects with high antibody level and those with lower levels (93.7% vs. 1.8%, respectively; p < 0.001). A high antibody level showed a sensitivity for viremia of 96.6% (95% confidence interval [CI], 93.8%-98.1%), a specificity of 96.6% (95% CI, 94.8%-97.8%), and a likelihood ratio of 28.6 (95% CI, 18.4%-44.6%). CONCLUSION: A high antibody level (S/CO ratio >/=20 by ChLIA HCV) clearly divides the viremic from the nonviremic blood donors and functions as an accurate serologic marker to guide the use of routine HCV RNA testing to confirm hepatitis C infection.