Home pregnancy test kits--one of the most widely used and conspicuous forms of do-it-yourself medicine--may give wrong results far more often than manufacturers would like women to believe, a new study has charged.
The study by a researcher at Milwaukee's Marquette University found that in three of the most widely used test kits, error rates ranged from 11% to more than 54%--figures that substantially exceed the accuracy claims made by manufacturers. Positive results were slightly more reliable than negative results, the Marquette study found. For the three kits, makers claimed overall accuracy rates of between 96% and 99%.
In the extreme, erroneous findings may lead to undetected tubal pregnancies that endanger women's lives and to possible emotional devastation for women suffering from infertility problems who may be wrongly led to believe they are pregnant.
While the Marquette study has quickly become controversial, experts questioned by The Times agreed that doubts about the accuracy of home pregnancy test kits and the wisdom of using them are widespread.
Several experts--including two in Los Angeles--said they routinely counsel women not to use home pregnancy tests at all because of the potential for wrong results, either positive or negative. These doctors say the advent of especially accurate urine tests that can be done in a doctor's office in a few minutes make reliance on home tests unnecessary.
This new generation of in-office tests is also priced competitively with many of the home kits, which retail for between just over $7 and just under $15. In Los Angeles, the new in-office test costs $15, too, doctors using it told The Times. The sophisticated new test can detect pregnancy before a menstrual period has been missed.
Manufacturers of the home test kits have quickly disputed the Marquette figures and the U.S. Food and Drug Administration says its own data have so far not shown error rates even approaching those reported in the new study. In fact, the American Journal of Public Health, which published the new study, also ran a brief letter from the FDA objecting to certain aspects of the Marquette research.
However, the FDA said it has never tested the kits in the way they were examined in Milwaukee--in a program where researchers evaluated kit accuracy under home-use conditions, as opposed to those of the laboratory.
The Marquette findings added new detail to research published in 1982 in which a University of Cincinnati team found that women using the kits failed to follow directions nearly a third of the time. A quarter of all results in that study told women they were not pregnant when, in fact, they were. Even a minor deviation from instructions furnished with the kits can lead to either a false-positive or false-negative reading.
Some experts believe the worst accuracy rates may be experienced by teen-aged girls, very young women and women with little education--three groups most likely to accept a home-test result and fail to seek confirmation of pregnancy from a doctor.
By postponing professional care, a woman may wait to seek an abortion or other options until her pregnancy is advanced. Such women may also continue drinking, smoking or taking drugs potentially damaging to the fetus--including aspirin--and expose their babies to high degrees of risk.
In question are e.p.t., Answer and Daisy 2 home pregnancy test kits. The products claim to be able to determine if a woman is pregnant in some cases as early as three days after a missed period and, in each case, by the time nine days have passed.
The pervasive skepticism among specialists in women's health care has apparently not cooled what has become a hot market for the home kits, of which half a dozen brands are widely available. In 1985, women used between 4 million and 7.2 million kits, for which they paid between $38 million and $48 million, according to estimates by Frost and Sullivan, a New York-based marketing research firm, and Biomedical Business International, an Orange County research organization.
There were 3.7 million births last year nationwide, according to federal government figures.
While demand has been essentially unchanged in recent years, marketing experts believe that, by 1989, use may increase to more than 8.9 million kits, according to Frost and Sullivan. The first generation of home pregnancy test kits entered the marketplace about 10 years ago.
The new study was done by researcher Mary Doshi of Marquette, who distributed e.p.t., Daisy 2 or Answer test kits to 109 Milwaukee women, ranging in age from 18 to over 30. A quarter of the women were nine days or less late for a menstrual period. Doshi has since left Marquette.