Mother-to-Infant Transmission of Hepatitis C Virus. Part 3
Testing for HIV-1 antibodies was done with a commercially available HIV-specific ELISA (Abbot HIV 1/2 gO; Abott Diagnostika). If the antibody-ELISA result was positive, it was confirmed by a Western blot (New LAV-BLOT I; Sanofi Diagnostics Pasteur). HIV-1–specific PCRs were done using a commercially available assay (Amplicor HIV-1 Monitor Test; Roche Diagnostic Systems), as recommended by the manufacturer
Clinical investigation Clinical data on HCV-infected mothers were assessed by questionnaires sent to mothers and their gynecologists immediately after delivery and by review of case histories and obstetric notes. The questionnaires asked for the number of previous deliveries, maternal age, and illicit drug use. The case histories and obstetric notes were reviewed for parity of the women, illicit drug use during pregnancy, gestational age, premature rupture of membranes, mode and course of delivery (elective vs. emergency cesarean section and perineal or vaginal laceration), medical interventions during delivery (e.g., episiotomy), umbilical cord–blood pH, APGAR (activity, pulse, grimace, appearance, and respiration) score, and birth weight of the child. Rupture of membranes was considered to be premature if it occurred before the first regular uterine contraction
Drug use was assessed by self-reports and toxicologic testing of urine samples, as described elsewhere. A woman was classified as positive for drug use during pregnancy if she had a positive urine toxicology result or a positive self-report. She was classified as negative for drug use if she had either a negative self-report and a negative urine screen or a negative self-report, if urine toxicology results were unavailable. HCV was reported to have been acquired through IDU for 41 (56%) women and from infected blood or blood products for 6 (8%) women. Other or unknown routes of acquisition were reported for 26 (36%) women. For 4 women with a history of IDU, urine toxicology results were negative during pregnancy, which is indicative of discontinuation of IDU
Data analysisThe effects of the different risk factors for perinatal HCV transmission were evaluated by unconditional logistic regression analysis. For the analysis of HCV load as a risk factor for vertical transmission, HCV-infected women with HCV RNA levels below the limits of detection were assigned a level of 10 copies/mL for logistic regression analysis. Because HCV load may change over time, only quantitative and qualitative HCV-PCR results obtained in samples that were taken within 150 days before and after delivery were used for the estimation of the risk of mother-to-infant transmission of HCV. For the evaluation of deviations from standard umbilical cord–blood pH values, a standard pH value of 7.27 was assumed. Univariate logistic regression results were subsequently checked for robustness by including all pairs of predictors of perinatal HCV transmission, with P<.1, in a multivariate analysis. Because of divergence of estimates, it was not possible to include >2 variables simultaneously in the analysis. P<.05 was considered to be statistically significant. All statistical analyses were performed using SPSS (version 10.0; SPSS) and EGRET (version 2.0.3; Cytel) software