Incorrect STD tests
show need for patients'
sex histories
False-positive gonorrhea tests for five Honolulu women in an eight-month period underscore the importance of doctors getting sexual history for patients, says Dr. Alan Katz, University of Hawaii epidemiology professor.
The number is small, but the false findings were traumatic for those affected, he said, noting that the psychological impact led to his investigation. "Every patient we saw was emotionally distraught."
One kicked her long-term partner out of the house based on the results, he said. Another ended an association of several years with her doctor after learning the test results were in error.
The tests were done by a private laboratory from October 2002 to May 2003, he said. They were among 16,641 tests for gonorrhea and chlamydia at the lab from July 2002 through June 2003, he said.
Of those, 1.6 percent had positive gonorrhea results.
There may have been more than the five false-positive cases, Katz said, explaining "it was just luck" to identify those because the women went to the state Health Department's STD/AIDS Diamond Head Clinic to follow up on the findings.
The women, ranging from 19 to 44 years old, all had long-term monogamous relationships with male partners, said Katz, the clinic's laboratory director.
He said some were married and others had been together a long time. Four of the men accompanied the women to the clinic.
"The first couple that came in was very upset; the guy was enraged," Katz said. "You want to believe your partner (wasn't fooling around), but the test says something different. ... He knew it was impossible, but he was very angry."
Three of the women had been screened for sexually transmitted diseases as part of a family-planning examination and two were tested to evaluate symptoms later diagnosed as a bacterial vaginosis condition, he said.
The women had different doctors, but urine-based nucleic acid amplification tests were done at the same laboratory. The test includes gonorrhea and chlamydia, a much more common condition.
Based on the positive results, the women were prescribed antimicrobial therapy and advised to have their partners examined and treated, Katz said.
"The screening test isn't at fault, he said. "It's excellent, but it's not perfect. ... Any test with a specificity less than 100 percent will have the potential for false positive results."
The potential for false positive results also increases if the test is used to test people from low-risk populations or areas with low gonorrhea rates, such as Hawaii, he said.
Katz was the lead author of an article discussing the false-positive test results in the March 15 issue of the journal Clinical Infectious Diseases. Co-authors were state epidemiologist Paul Effler; Roy Ohye, Barbara Brouillet and Maria Veneranda Lee with the Health Department's STD/AIDS Prevention Branch; and Peter Whiticar, branch chief.
Both the women and men were given physical exams, a different nucleic acid amplified test and culture-based tests at the state clinic, Katz said in an interview.
All were negative for gonorrhea infection.
The clinic also obtained the women's sexual histories. None suggested they were high risk for contracting a sexually transmitted disease, but STD screening was justified for two women with vaginal discharges, Katz said.
There was no documentation that the doctors obtained sexual histories of the women, he said, noting the extent of sexual history was to inquire about their marital status.
The doctors also did no retesting to confirm the positive results, except in one case with a "gray zone" result, he said. They were "taken aback" when told the results were false, he said.
Katz said studies have shown physicians aren't comfortable talking about sex and obtaining sexual histories.
"We need to make this a normal part of the patient-physician encounter," he said.
Doctors are better able to interpret test results correctly when they know a patient's sexual history, he said.
A doctor who knows a patient is in a long-term monogamous relationship can question a positive test for gonorrhea and retest, "perhaps preventing unnecessary psychological distress to a patient who's not expecting bad news," he said.
Katz said the UH John A. Burns School of Medicine and the Department of Health are trying to educate students and physicians in the community about the need to take sexual histories.
The laboratory in the false positive cases "was extremely helpful," he said. It is including a reminder with lab results that false positive results could occur and the patient may want to consider retesting if his or her sexual history doesn't support it.
Katz noted an article in The Lancet journal about uses and abuses of screening tests that said, "Although failing to diagnose sexually transmitted diseases can have important health implications, incorrectly labeling people as infected can wreck marriages and damage lives."
He said he doesn't know of any lawsuits filed locally over erroneous STD test results but that is a concern.
Doctors who don't obtain sexual histories may miss sexually active adolescents, older people and partners with outside sexual relationships who should be screened for sexually transmitted diseases, he said.
"Not a lot of 10- to 14-year-old kids are sexually active, but those that are, are at high risk for gonorrhea and chlamydia," he said.
In an editorial accompanying the article, Dr. Jeffrey Klausner, head of the STD program in San Francisco, agreed that all patients should routinely be asked if they are sexually active.
He said the response should be documented and followed up with questions about the specific sexual activity and the number of partners involved.
"The failure to elicit a sexual history from persons at risk for STDs and HIV infection has been called 'tantamount to malpractice' and on the order of not taking a history of drug allergies in patients being prescribed medications," Klausner wrote.
The adverse impact of the false screening tests in Hawaii points to the need "for greater national and local leadership to educate clinicians in the proper use of STD screening tests," he said. "The response in Hawaii to create a laboratory-based educational program was enlightened."
