Health
Briefs
Evaluation of a 'Do-lt-Yourself' Pregnancy Test LAWRENCE D. BAKER, MD, LOUISE W. YERT, BS, MARY C. CHASE, BS, and EDWIN DALE, PHD
Introduction
Theoretical Effectiveness Experiments
Numerous pregnancy tests are available for use by commercial laboratories and physicians or other qualified health personnel. Recently, "do-it-yourself' tests have been marketed at retail outlets, such as drug stores and department stores, and sold directly to the consumer. In this study, one of these tests, the Ova II Preliminary Screening Test for Pregnancy (Ova II), was evaluated by comparing its results with the actual diagnosis and with standard laboratory tests for urinary chorionic gonadotrophin. Because the test is performed by the woman herself, it was necessary to determine both its theoretical and use leffectiveness. Theoretical effectiveness was defined as the accuracy of the test when performed by professional laboratory personnel according to the manufacturer's instructions. In contrast, use effectiveness was defined as the accuracy of the product when performed by the untrained consumer.
There were 2 experiments done to evaluate theoretical effectiveness. The participants in the first experiment were women admitted to Grady Memorial Hospital for a suction curettage outpatient abortion, and employees of the Center for Disease Control who at the time of the pregnancy test believed themselves not pregnant. On each urine sample a CDC research chemist performed an Ova II and WampoleUCG test. The Wampole-UCG is a standard laboratory pregnancy test considered 97 per cent-99 per cent accurate.3 To confirm pregnancy in the abortion patients, hospital pathology reports or the physician's description of the products of conception were used. For the CDC employees believed not pregnant, we considered the occurrence of a subsequent menstrual period to be confirmation of the absence of pregnancy or, if the subsequent menstrual cycle was abnormal, we performed another Wampole-UCG test. Table I shows the results of the experiment. All of the 18 abortion patients were pregnant. The Ova II test agreed with the diagnosis in only 9 of these 18 patients. All of the 22 CDC employees were not pregnant. The Ova II result matched the diagnosis in only 9 of these 22 cases. The Wampole-UCG test agreed with the true diagnosis in all 40 of the cases tested. In this first experiment for determining theoretical effectiveness, the technician was aware of the likely diagnosis before she performed the Ova II and the Wampole-UCG. To eliminate such a bias we performed a second theoretical effectiveness experiment. We obtained urine from women who came to the Grady Hospital Family Planning Clinic requesting a pregnancy test. On each urine specimen, a research
Materials and Methods Ova II is a non-immunologic, colorimetric test, which, according to the manufacturer, is "a preliminary screening test for determining whether urine samples tested contain substances normally present in the urine of pregnant women. These substances are usually detectable 2 to 4 weeks after conception, but variances exist from woman to woman."' The test is designed for use with fresh urine samples. The kit comes with 2 solutions, Reagent A, consisting of hydrochloric acid, dinitrophenylhydrazine, and methyl red; and Reagent B, sodium hydroxide.2
From the U.S. Department of Health, Education, and Welfare, Public Health Service, Center for Disease Control, Bureau of Epidemiology, and the Department of Gynecology and Obstetrics; Emory University School of Medicine, Atlanta, GA. Address reprint requests to Lawrence D. Baker, MD, Northside Family Planning Services, Inc., 5675 Peachtree Dunwoody Road, Suite 410, Atlanta, GA 30342. This paper, submitted September 17, 1975, and accepted for publication in the Journal November 11, 1975, is based on a presentation at the 101st Annual Meeting of the American Public Health Association in San Francisco, CA.
166
TABLE 1-Relationship Between True Diagnosis and OVA 11 Test Theoretical Effectiveness-Experiment I True Diagnosis
Pregnant Not Pregnant
Total
18 22
OVA lI Result Agreeing with Diagnosis No. Rate/1 00
9 9
50.0 (sensitivity) 40.9 (specificity)
AJPH February, 1976, Vol. 66, No. 2
PUBLIC HEALTH BRIEFS
technician at the McCord Cross Laboratory of Reproductive Physiology, Emory University School of Medicine, performed an Ova II test. In addition, a technician at the Grady Memorial Hospital Serology Laboratory performed a Gravindex test. This is a standard laboratory test for pregnancy considered more than 95 per cent accurate.3 Table 2 shows
the study. Of these, 15 either did not perform the Ova II test or did not report its results, and 12 were lost to follow-up. Table 3 shows the results of Ova II test for the other 46 women in relation to true diagnosis. Overall, the Ova II agreed with the true diagnosis in only 10 of the 19 pregnant women and in 14 of the 27 non-pregnant women. The WampoleUCG result agreed with true diagnosis in all cases of nonpregnancy and in all but one case of pregnancy.
TABLE 2-Relationship Between Ova II and Gravindex Results Theoretical Effectiveness-Experiment 2 Result of Gravindex
Total
OVA lI Agreeing with Gravindex
Positive Negative
20 21
10 13
Discussion Rate/100 50.0 (sensitivity) 61.9 (specificity)
the results of the Ova II and the Gravindex on each urine specimen. Of the 20 women with a positive Gravindex, only 10 had the same Ova II result; of the 21 women with a negative Gravindex, only 13 had the same Ova II result.
Use Effectiveness Experiment Participants in the evaluation of the use effectiveness of the Ova II kit were predominantly lower socioeconomic status women coming to the Grady Hospital Family Planning Clinic for pregnancy testing. Each woman was given an Ova II kit to test her own urine at home. In addition, a sample of urine was collected and a Wampole-UCG test was performed by the CDC research chemist. We told each participant that the results from both tests would determine if they were pregnant. We asked each study participant to telephone the following day to report the results of the Ova II pregnancy test and to learn the results of the Wampole-UCG. When there was a conflict between the results of the Ova II and the Wampole-UCG, we counseled the women on the basis of the Wampole-UCG results. Documentation of pregnancy was based upon a confirmatory physical examination, or a positive pathology report following a legal abortion. Documentation of the absence of pregnancy was based upon the occurrence of either a subsequent normal menstrual period, a subsequent negative pregnancy test, or physical examination. Seventy-three family planning clinic patients entered TABLE 3-Relationship Between True Diagnosis and Results of Ova II and Wampole-UCG Test Use Effectiveness Experiment
The potential advantages of a readily available, accurate and reliable "do-it-yourself' non-prescription pregnancy test are that it would allow a woman to be the first person to know that she is pregnant (some women prefer to wait until they are sure they are pregnant before visiting their physician), and it would make earlier diagnosis of pregnancy possible. Early pregnancy confirmation would result in earlier prenatal care or earlier abortions, thereby contributing to better maternal health. To realize these potential advantages, however, a "doit-yourself' pregnancy test must be accurate in the hands of the consumer, not just in the trained hands of laboratory personnel. Tests having significant numbers of false-positives and false-negatives could be detrimental. A false positive pregnancy test could cause the woman unnecessary psychological stress and expose her to the expense and potential risk of an unnecessary legal or illegal abortion procedure. A false negative pregnancy test could delay the beginning of prenatal care or an early legal abortion. We had expected that the accuracy of the product when used by the consumer would be less than that obtained by trained personnel. Our studies showed that the theoretical accuracy of the Ova II kit was approximately 50 per cent. With these random results it was not surprising that theoretical effectiveness matched use effectiveness. In December 1972, the FDA requested and received compliance from the manufacturer for the withdrawal of the product from the consumer market place. However, in July 1975, a Federal judge ruled that the FDA had no power to restrict the sale of Ova II. The final outcome of the Ova II saga now awaits judicial appeal or new legislation. Future do-it-yourself pregnancy tests may prove to have higher degrees of theoretical accuracy than Ova II. However, in the interests of consumer protection it is clear that before such tests are marketed, accuracy and reliability when used by the consumer must be ascertained and meet acceptable standards.
REFERENCES
True Diagnosis
Pregnant Not Pregnant
Total
19 27
AJPH February, 1976, Vol. 66, No. 2
OVA II Result Agreeing with Diagnosis No. Rate/i 00
10 14
52.6 (sensitivity) 51.9 (specificity)
1. Faraday Laboratories. Instructions for Ova II Preliminary Screening Test for Pregnancy. Package insert. 2. U.S. Patent Office. Method of testing urine for pregnancy. Patent #3,226,196, Dec. 28, 1965. 3. Cabrera, H. A., A Comprehensive Evaluation of Pregnancy Tests, Am. Journal of Obstetrics and Gynecology, Vol. 103:3238, 1969.
167
Briefs
Evaluation of a 'Do-lt-Yourself' Pregnancy Test LAWRENCE D. BAKER, MD, LOUISE W. YERT, BS, MARY C. CHASE, BS, and EDWIN DALE, PHD
Introduction
Theoretical Effectiveness Experiments
Numerous pregnancy tests are available for use by commercial laboratories and physicians or other qualified health personnel. Recently, "do-it-yourself' tests have been marketed at retail outlets, such as drug stores and department stores, and sold directly to the consumer. In this study, one of these tests, the Ova II Preliminary Screening Test for Pregnancy (Ova II), was evaluated by comparing its results with the actual diagnosis and with standard laboratory tests for urinary chorionic gonadotrophin. Because the test is performed by the woman herself, it was necessary to determine both its theoretical and use leffectiveness. Theoretical effectiveness was defined as the accuracy of the test when performed by professional laboratory personnel according to the manufacturer's instructions. In contrast, use effectiveness was defined as the accuracy of the product when performed by the untrained consumer.
There were 2 experiments done to evaluate theoretical effectiveness. The participants in the first experiment were women admitted to Grady Memorial Hospital for a suction curettage outpatient abortion, and employees of the Center for Disease Control who at the time of the pregnancy test believed themselves not pregnant. On each urine sample a CDC research chemist performed an Ova II and WampoleUCG test. The Wampole-UCG is a standard laboratory pregnancy test considered 97 per cent-99 per cent accurate.3 To confirm pregnancy in the abortion patients, hospital pathology reports or the physician's description of the products of conception were used. For the CDC employees believed not pregnant, we considered the occurrence of a subsequent menstrual period to be confirmation of the absence of pregnancy or, if the subsequent menstrual cycle was abnormal, we performed another Wampole-UCG test. Table I shows the results of the experiment. All of the 18 abortion patients were pregnant. The Ova II test agreed with the diagnosis in only 9 of these 18 patients. All of the 22 CDC employees were not pregnant. The Ova II result matched the diagnosis in only 9 of these 22 cases. The Wampole-UCG test agreed with the true diagnosis in all 40 of the cases tested. In this first experiment for determining theoretical effectiveness, the technician was aware of the likely diagnosis before she performed the Ova II and the Wampole-UCG. To eliminate such a bias we performed a second theoretical effectiveness experiment. We obtained urine from women who came to the Grady Hospital Family Planning Clinic requesting a pregnancy test. On each urine specimen, a research
Materials and Methods Ova II is a non-immunologic, colorimetric test, which, according to the manufacturer, is "a preliminary screening test for determining whether urine samples tested contain substances normally present in the urine of pregnant women. These substances are usually detectable 2 to 4 weeks after conception, but variances exist from woman to woman."' The test is designed for use with fresh urine samples. The kit comes with 2 solutions, Reagent A, consisting of hydrochloric acid, dinitrophenylhydrazine, and methyl red; and Reagent B, sodium hydroxide.2
From the U.S. Department of Health, Education, and Welfare, Public Health Service, Center for Disease Control, Bureau of Epidemiology, and the Department of Gynecology and Obstetrics; Emory University School of Medicine, Atlanta, GA. Address reprint requests to Lawrence D. Baker, MD, Northside Family Planning Services, Inc., 5675 Peachtree Dunwoody Road, Suite 410, Atlanta, GA 30342. This paper, submitted September 17, 1975, and accepted for publication in the Journal November 11, 1975, is based on a presentation at the 101st Annual Meeting of the American Public Health Association in San Francisco, CA.
166
TABLE 1-Relationship Between True Diagnosis and OVA 11 Test Theoretical Effectiveness-Experiment I True Diagnosis
Pregnant Not Pregnant
Total
18 22
OVA lI Result Agreeing with Diagnosis No. Rate/1 00
9 9
50.0 (sensitivity) 40.9 (specificity)
AJPH February, 1976, Vol. 66, No. 2
PUBLIC HEALTH BRIEFS
technician at the McCord Cross Laboratory of Reproductive Physiology, Emory University School of Medicine, performed an Ova II test. In addition, a technician at the Grady Memorial Hospital Serology Laboratory performed a Gravindex test. This is a standard laboratory test for pregnancy considered more than 95 per cent accurate.3 Table 2 shows
the study. Of these, 15 either did not perform the Ova II test or did not report its results, and 12 were lost to follow-up. Table 3 shows the results of Ova II test for the other 46 women in relation to true diagnosis. Overall, the Ova II agreed with the true diagnosis in only 10 of the 19 pregnant women and in 14 of the 27 non-pregnant women. The WampoleUCG result agreed with true diagnosis in all cases of nonpregnancy and in all but one case of pregnancy.
TABLE 2-Relationship Between Ova II and Gravindex Results Theoretical Effectiveness-Experiment 2 Result of Gravindex
Total
OVA lI Agreeing with Gravindex
Positive Negative
20 21
10 13
Discussion Rate/100 50.0 (sensitivity) 61.9 (specificity)
the results of the Ova II and the Gravindex on each urine specimen. Of the 20 women with a positive Gravindex, only 10 had the same Ova II result; of the 21 women with a negative Gravindex, only 13 had the same Ova II result.
Use Effectiveness Experiment Participants in the evaluation of the use effectiveness of the Ova II kit were predominantly lower socioeconomic status women coming to the Grady Hospital Family Planning Clinic for pregnancy testing. Each woman was given an Ova II kit to test her own urine at home. In addition, a sample of urine was collected and a Wampole-UCG test was performed by the CDC research chemist. We told each participant that the results from both tests would determine if they were pregnant. We asked each study participant to telephone the following day to report the results of the Ova II pregnancy test and to learn the results of the Wampole-UCG. When there was a conflict between the results of the Ova II and the Wampole-UCG, we counseled the women on the basis of the Wampole-UCG results. Documentation of pregnancy was based upon a confirmatory physical examination, or a positive pathology report following a legal abortion. Documentation of the absence of pregnancy was based upon the occurrence of either a subsequent normal menstrual period, a subsequent negative pregnancy test, or physical examination. Seventy-three family planning clinic patients entered TABLE 3-Relationship Between True Diagnosis and Results of Ova II and Wampole-UCG Test Use Effectiveness Experiment
The potential advantages of a readily available, accurate and reliable "do-it-yourself' non-prescription pregnancy test are that it would allow a woman to be the first person to know that she is pregnant (some women prefer to wait until they are sure they are pregnant before visiting their physician), and it would make earlier diagnosis of pregnancy possible. Early pregnancy confirmation would result in earlier prenatal care or earlier abortions, thereby contributing to better maternal health. To realize these potential advantages, however, a "doit-yourself' pregnancy test must be accurate in the hands of the consumer, not just in the trained hands of laboratory personnel. Tests having significant numbers of false-positives and false-negatives could be detrimental. A false positive pregnancy test could cause the woman unnecessary psychological stress and expose her to the expense and potential risk of an unnecessary legal or illegal abortion procedure. A false negative pregnancy test could delay the beginning of prenatal care or an early legal abortion. We had expected that the accuracy of the product when used by the consumer would be less than that obtained by trained personnel. Our studies showed that the theoretical accuracy of the Ova II kit was approximately 50 per cent. With these random results it was not surprising that theoretical effectiveness matched use effectiveness. In December 1972, the FDA requested and received compliance from the manufacturer for the withdrawal of the product from the consumer market place. However, in July 1975, a Federal judge ruled that the FDA had no power to restrict the sale of Ova II. The final outcome of the Ova II saga now awaits judicial appeal or new legislation. Future do-it-yourself pregnancy tests may prove to have higher degrees of theoretical accuracy than Ova II. However, in the interests of consumer protection it is clear that before such tests are marketed, accuracy and reliability when used by the consumer must be ascertained and meet acceptable standards.
REFERENCES
True Diagnosis
Pregnant Not Pregnant
Total
19 27
AJPH February, 1976, Vol. 66, No. 2
OVA II Result Agreeing with Diagnosis No. Rate/i 00
10 14
52.6 (sensitivity) 51.9 (specificity)
1. Faraday Laboratories. Instructions for Ova II Preliminary Screening Test for Pregnancy. Package insert. 2. U.S. Patent Office. Method of testing urine for pregnancy. Patent #3,226,196, Dec. 28, 1965. 3. Cabrera, H. A., A Comprehensive Evaluation of Pregnancy Tests, Am. Journal of Obstetrics and Gynecology, Vol. 103:3238, 1969.
167
