AMERICAN JOURNAL OF PERINATOLOCY/VOLUME 9, NUMBER 4
July 1992
SEROPREVALENCE OF HUMAN IMMUNODEFICIENCY VIRUS TYPE 1 AMONG PREGNANT WOMEN John T. Repke, M.D., Timothy R. Townsend, M.D., Jacqueline S. Coberly, Ph.D., Geraldine M. McQuillan, Ph.D., Neal A. Halsey, M.D., and Thomas C. Quinn, M.D.
ABSTRACT
Serologic testing of pregnant women for evidence of human immunodeficiency virus (HIV-1) infection is an important means of monitoring the course and possibly reducing the spread of the HIV-1 epidemic. Serologic testing for HIV-1 without the knowledge or consent of the women and without personal identifiers to link them to the test results (unlinked testing) can provide useful data for tracking the epidemic. Systematic studies provide information on changes in the prevalence and the characteristics of infected women. These data also allow for planning future health care resource needs for the women and their infected infants. Several seroprevalence studies of pregnant women or their newborns have been published.1-5 Reported rates have ranged from 0% among 1000 women in central Wisconsin to 29.6% among 115 women in Baltimore who indicated they engaged in high-risk behavior.1 We have performed unlinked HIV-1 seroprevalence studies of pregnant women served by the Johns Hopkins Hospital using residual blood from hepatitis B virus (HBV) infection surveys conducted in 1985 and 1986—1987. Our purpose for these epidemiologic studies was to determine the prevalence in our population for health care resource planning needs and to determine if readily identifiable high prevalence sub-
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Five (0.74%) of 678 women delivering in 1985 at a tertiary referral hospital for highrisk pregnancies and 16 (1.34%) of 1198 women visiting an urban prenatal obstetrics clinic in 1986-1987 had serologic evidence of human immunodeficiency virus type 1 (HIV-1) infection. Unlinked testing (removal of personal identifiers from the blood specimen and the epidemiologic data sheet) of residual serum from hepatitis B virus serologic testing was used. Neither age, marital status, payor status, nor serologic markers of hepatitis B virus infection was useful in identifying women at risk for HIV-1 infection. Asa result of these data, we have initiated a program in which counseling is offered to all women and testing for those who consent. Unlinked testing of women who refuse consent is performed for epidemiologic purposes. This will allow us to continue to plan for health care resource needs and to track the course of the epidemic in various subgroups of pregnant women.
groups existed that could be targeted for testing and counseling, since studies have revealed that screening for selfadmitted high-risk behavior for HBV and HIV-1 infection is unreliable.4-6 MATERIALS AND METHODS From May 3 to September 8, 1985, all women (n = 692) delivering at the Johns Hopkins Hospital were participants in a hepatitis B virus seroprevalence study.6 There was sufficient residual serum from 678 women to permit HIV-1 testing. Starting October 1, 1986, all women attending the Prenatal Obstetric Clinic were tested for hepatitis B surface antigen (HbsAg). As of October 31, 1987, 1198 consecutive women had been tested for HbAg and residual serum was used for HIV-1 testing. Personal identifiers were removed from the specimen containers and from data sheets that contained epidemiologic data so that no test result could be linked to an individual. Approval for this study was obtained from the Joint Committee on Clinical Investigation of the Johns Hopkins Medical Institutions. Serum samples from both populations were analyzed in the same laboratory in two batches of 678 and 1198,
The Department of Gynecology and Obstetrics and the Department of Hospital Epidemiology, The Johns Hopkins Hospital; the Department of Medicine, The Johns Hopkins University School of Medicine; and the Departments of Epidemiology and International Health, The Johns Hopkins University School of Hygiene and Public Health, Baltimore, Maryland Reprint requests: Dr. Repke, Department of Gynecology and Obstetrics, Houck 228, The Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, MD 21205 Copyright © 1992 by Thieme Medical Publishers, Inc., 381 Park Avenue South, New York, NY 10016. All rights reserved.
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AMERICAN JOURNAL OF PERINATOLOGY/VOLUME 9, NUMBER 4 July 1992
respectively. A sample was considered HIV-1 positive if it was repeatedly enzyme-linked immunosorbent assay (ELISA) reactive (Organon Technika, Charleston, S.C.) and if western blot (Duplont, Wilmington, Del.) analysis revealed antibodies to both envelope and core proteins.
Table 2. Relationship of Serologic Markers for HBV and HIV-1 Infection Among Women Delivering at The Johns Hopkins Hospital, 1985 HIV-1 Antibody HBV Markers*
Five (0.74%) of the 678 women delivering at the Hospital in 1985 and 16 (1.34%) of the 1198 women visiting the clinic in 1986—1987 were HIV-1 seropositive. The difference between these prevalence rates is not statistically significant (p = 0.17, Fisher's exact test; B = 0.69, Poisson). No association between HIV-1 seropositivity and age, marital status (single or ever married), or payor status (whether or not Medicaid paid for the obstetric services) was found in either population (Table 1). There was a statistically significant (p = 0.005, Fisher's exact test) association between HBV serologic markers (HbsAg or antibody to the core or surface antigen) and HIV-1 seropositivity among women delivering at the hospital (Table 2). The sensitivity (60%), specificity (92%), and positive predictive value (5%) of HBV markers for identifying HIV-1 infected women was, however, poor. The low positive predictive value would be anticipated due to the low prevalence (HBV, 9%, HIV 0.74%) of these infections. Since only hepatitis B surface antigenemia was determined in the 1986-1987 study, the association between HBV and HIV infection could not be determined in that population. There were statistically significant differences (p
July 1992
SEROPREVALENCE OF HUMAN IMMUNODEFICIENCY VIRUS TYPE 1 AMONG PREGNANT WOMEN John T. Repke, M.D., Timothy R. Townsend, M.D., Jacqueline S. Coberly, Ph.D., Geraldine M. McQuillan, Ph.D., Neal A. Halsey, M.D., and Thomas C. Quinn, M.D.
ABSTRACT
Serologic testing of pregnant women for evidence of human immunodeficiency virus (HIV-1) infection is an important means of monitoring the course and possibly reducing the spread of the HIV-1 epidemic. Serologic testing for HIV-1 without the knowledge or consent of the women and without personal identifiers to link them to the test results (unlinked testing) can provide useful data for tracking the epidemic. Systematic studies provide information on changes in the prevalence and the characteristics of infected women. These data also allow for planning future health care resource needs for the women and their infected infants. Several seroprevalence studies of pregnant women or their newborns have been published.1-5 Reported rates have ranged from 0% among 1000 women in central Wisconsin to 29.6% among 115 women in Baltimore who indicated they engaged in high-risk behavior.1 We have performed unlinked HIV-1 seroprevalence studies of pregnant women served by the Johns Hopkins Hospital using residual blood from hepatitis B virus (HBV) infection surveys conducted in 1985 and 1986—1987. Our purpose for these epidemiologic studies was to determine the prevalence in our population for health care resource planning needs and to determine if readily identifiable high prevalence sub-
Downloaded by: University of British Columbia. Copyrighted material.
Five (0.74%) of 678 women delivering in 1985 at a tertiary referral hospital for highrisk pregnancies and 16 (1.34%) of 1198 women visiting an urban prenatal obstetrics clinic in 1986-1987 had serologic evidence of human immunodeficiency virus type 1 (HIV-1) infection. Unlinked testing (removal of personal identifiers from the blood specimen and the epidemiologic data sheet) of residual serum from hepatitis B virus serologic testing was used. Neither age, marital status, payor status, nor serologic markers of hepatitis B virus infection was useful in identifying women at risk for HIV-1 infection. Asa result of these data, we have initiated a program in which counseling is offered to all women and testing for those who consent. Unlinked testing of women who refuse consent is performed for epidemiologic purposes. This will allow us to continue to plan for health care resource needs and to track the course of the epidemic in various subgroups of pregnant women.
groups existed that could be targeted for testing and counseling, since studies have revealed that screening for selfadmitted high-risk behavior for HBV and HIV-1 infection is unreliable.4-6 MATERIALS AND METHODS From May 3 to September 8, 1985, all women (n = 692) delivering at the Johns Hopkins Hospital were participants in a hepatitis B virus seroprevalence study.6 There was sufficient residual serum from 678 women to permit HIV-1 testing. Starting October 1, 1986, all women attending the Prenatal Obstetric Clinic were tested for hepatitis B surface antigen (HbsAg). As of October 31, 1987, 1198 consecutive women had been tested for HbAg and residual serum was used for HIV-1 testing. Personal identifiers were removed from the specimen containers and from data sheets that contained epidemiologic data so that no test result could be linked to an individual. Approval for this study was obtained from the Joint Committee on Clinical Investigation of the Johns Hopkins Medical Institutions. Serum samples from both populations were analyzed in the same laboratory in two batches of 678 and 1198,
The Department of Gynecology and Obstetrics and the Department of Hospital Epidemiology, The Johns Hopkins Hospital; the Department of Medicine, The Johns Hopkins University School of Medicine; and the Departments of Epidemiology and International Health, The Johns Hopkins University School of Hygiene and Public Health, Baltimore, Maryland Reprint requests: Dr. Repke, Department of Gynecology and Obstetrics, Houck 228, The Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, MD 21205 Copyright © 1992 by Thieme Medical Publishers, Inc., 381 Park Avenue South, New York, NY 10016. All rights reserved.
293
AMERICAN JOURNAL OF PERINATOLOGY/VOLUME 9, NUMBER 4 July 1992
respectively. A sample was considered HIV-1 positive if it was repeatedly enzyme-linked immunosorbent assay (ELISA) reactive (Organon Technika, Charleston, S.C.) and if western blot (Duplont, Wilmington, Del.) analysis revealed antibodies to both envelope and core proteins.
Table 2. Relationship of Serologic Markers for HBV and HIV-1 Infection Among Women Delivering at The Johns Hopkins Hospital, 1985 HIV-1 Antibody HBV Markers*
Five (0.74%) of the 678 women delivering at the Hospital in 1985 and 16 (1.34%) of the 1198 women visiting the clinic in 1986—1987 were HIV-1 seropositive. The difference between these prevalence rates is not statistically significant (p = 0.17, Fisher's exact test; B = 0.69, Poisson). No association between HIV-1 seropositivity and age, marital status (single or ever married), or payor status (whether or not Medicaid paid for the obstetric services) was found in either population (Table 1). There was a statistically significant (p = 0.005, Fisher's exact test) association between HBV serologic markers (HbsAg or antibody to the core or surface antigen) and HIV-1 seropositivity among women delivering at the hospital (Table 2). The sensitivity (60%), specificity (92%), and positive predictive value (5%) of HBV markers for identifying HIV-1 infected women was, however, poor. The low positive predictive value would be anticipated due to the low prevalence (HBV, 9%, HIV 0.74%) of these infections. Since only hepatitis B surface antigenemia was determined in the 1986-1987 study, the association between HBV and HIV infection could not be determined in that population. There were statistically significant differences (p
