STD Quarterly: Test for STDs from single Pap specimen
October 1, 2002 4 minutes read
Clinicians now can monitor for cervical lesions, as well as human papillomavirus (HPV), chlamydia, and gonorrhea infection, using a single ThinPrep Pap Test specimen. The Food and Drug Administration (FDA) recently approved testing for Chlamydia trachomatis and Neisseria gonorrhoeae directly from the ThinPrep Pap Test collection vial using the COBAS Amplicor automated system developed by Basel, Switzerland-based Roche Diagnostics Corp.
One specimen yields several screens
About half of U.S. providers currently use the ThinPrep technology for Pap tests, estimates Jeff Keene, corporate spokesman for manufacturer Cytyc Corp. of Boxborough, MA. Cytyc gained FDA approval for the liquid-based ThinPrep Pap Test in 1996, with HPV testing approval awarded in 1997. With one collection medium, clinicians can take a single endocervical sample with the ability to run several screens on the specimen, he explains.
Providers are performing more chlamydia tests following the U.S. Preventive Services Task Force’s 2001 recommendation that all sexually active women ages 25 and younger be routinely screened for the sexually transmitted disease (STD). (See "Task force calls for chlamydia screening," Contraceptive Technology Update, July 2001, p. 81.)
The task force recommendation calls for all women to be routinely screened for chlamydia if they:
- are sexually active and age 25 or younger;
- have more than one sexual partner, regardless of age;
- have had a STD in the past, regardless of age;
- do not use condoms consistently and correctly, regardless of age.
Chlamydia screening of sexually active young women ages 15-25 now is one of the performance measures included in the Washington, DC-based National Committee for Quality Assurance’s Health Plan Employer Data and Information Set (HEDIS). HEDIS is the most widely used system for assessing managed care performance. The performance measure was added in 2000. (Read about the addition of the performance measure in the February 2000 CTU article, "Women’s health issues included in managed care report card," p. 17.)
Review the research
Scientists conducted a prospective study to determine whether the automated COBAS Amplicor test could detect Chlamydia trachomatis in cervical specimens collected in the PreservCyt transport medium used in the ThinPrep Pap Test.1 A total of 1,000 cervical specimens were collected from young women during routine Pap smear tests. Only specimens with normal cytology and in which the gynecologist found no clinical evidence of urogenital infections were selected.
The samples were stored in PreservCyt transport medium, then tested for chlamydial infection. To confirm the positive samples, the test was repeated on new endocervical swab specimens collected in transport medium used in the COBAS Amplicor test. Results indicated that the ThinPrep Pap Test may enable providers to monitor for cervical lesions and chlamydial infection with a single endocervical infection.
Tests uncommon in Title X clinics
While the ThinPrep Pap Test is fast becoming the standard of care in private providers’ offices, it is rare in use as a first-line primary screen in federally funded Title X clinics due to costs, says Judith DeSarno, chief executive officer of the Washington, DC-based National Family Planning and Reproductive Health Association (NFPRHA). If the technology is employed, it is used as a secondary screen after an abnormal conventional Pap smear; even then, less than half of Title X clinics are able to use the technology, she notes.
An informal survey at the organization’s recent annual meeting shows that almost no clinics are performing routine HPV screens from the ThinPrep technology. The ability to perform HPV screens from a ThinPrep sample can be useful, since newly released guidelines allow laboratories to test ASC-US (atypical squamous cells of undetermined significance) liquid-based samples used for the original Pap test for HPV, which eliminates the need for a repeat provider visit.2 Known as "reflex" testing, this form of testing quickly reassures women who are HPV-negative they are unlikely to have a high-grade lesion and that they simply need regular Pap tests. Women who are HPV-positive are identified and scheduled for further evaluation. (Read more about the new guidelines in the July 2002 CTU article, "Improve cervical cancer screening: Review new terminology, guidelines," p. 73.)
DeSarno says that while Cytyc Corp. is working with NFPRHA in exploring cost alternatives for the collection technology, clinics still have to pay the higher lab costs for processing the ThinPrep samples. Since clinics have been unable to afford the ThinPrep Pap Tests, it is doubtful they will be able to take advantage of the "one-stop" specimen testing for HPV, chlamydia, and gonorrhea.
"I think this is a giant leap forward in sort of a one-stop for a Pap test," she says. "I think there are some hard decisions down the road for Title X clinics."
References
1. Bianchi A, Moret F, Desrues JM, et al. PreservCyt transport medium used for the ThinPrep Pap test is a suitable medium for detection of Chlamydia trachomatis by the COBAS Amplicor CT/NG test: Results of a preliminary study and future implications. J Clin Microbiol 2002; 40: 1,749-1,754.
2. Wright Jr. TC, Cox JT, Massad LS, et al. 2001 Consensus Guidelines for the management of women with cervical cytological abnormalities. JAMA 2002; 287:2,120-2,129.
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