Study finds self-collected specimens comparable to physician-collected specimens for STI screening accuracy
February 8, 2018
A new study in Nairobi, Kenya, found that self-collection of specimens was comparable to physician-collection for the screening of four sexually transmitted infections in a population of female sex workers.
Researchers from the University of North Carolina at Chapel Hill’s Gillings School of Global Public Health who contributed to the study include Jennifer S. Smith, PhD, professor of epidemiology, Alexandre Lockhart, biostatistics student, and Matt Psioda, PhD, research assistant professor of biostatistics. Smith also is a member of UNC’s Lineberger Comprehensive Cancer Center.
The study aimed to 1) compare the detection of sexually transmitted infections (STIs) using self-collected specimens versus physician-collected specimens and 2) investigate the acceptability of self-collection. A total of 350 female sex workers in a high-risk, low-resource setting participated in the 18-month study between 2009 and 2011.
First, the women self-collected a vaginal brush specimen using simple pictorial instructions. Next, a physician conducted a pelvic examination to obtain a cervical specimen. Physician- and self-collected specimens were then tested for Chlamydia trachomatis (CT), Neisseria gonorrhoeae (GC), Trichomonas vaginalis (TV) and Mycoplasma genitalium (MG) using Aptima assays. Screening results were compared at baseline and at 3-month intervals over the 18 months of follow-up.
Self- and physician-collected specimens resulted in similar levels of diagnostic detection, except in the case of MG, which consistently was detected more commonly in self-collected specimens. The baseline STI prevalence in self-collected samples was 2.9 percent for GC, 5.2 percent for CT, 9.2 percent for TV and 20.1 percent for MG. For physician-collected samples, the results were 2.3 percent, 3.7 percent, 7.2 percent and 12.9 percent, respectively.
Most participants found self-collection easy (94 percent) and comfortable (89 percent) at the beginning of the study, with responses becoming slightly more favorable over study follow-up, which suggests that participants became more comfortable with the self-collection process over time.
“Our results are important given that the detection rates of four sexually transmitted infections in samples collected by women themselves were similar to, if not higher than, physician-collected samples,” Smith said. “The data demonstrate how technological advances in diagnostic assays can allow for improved access to screening across settings.”
In high-risk, low-resource settings, therefore, STI screening with self-collected specimens provides a reliable and acceptable alternative to screening with physician-collected specimens. Given that untreated STIs may increase the risk of HIV acquisition, pelvic inflammatory disease and preterm birth, diagnosis and control of these infections is an important global public health concern. Self-collection to increase access to STI screening may be one viable solution for future prevention efforts.
The full article, titled “Prospective Evaluation of Cervico-vaginal Self and Cervical Physician-collection for the Detection of Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, and Mycoplasma genitalium Infections,” was published online Jan. 2 by the journal Sexually Transmitted Diseases.
Co-authors from outside the Gillings School include Jie Ting, in the University of California’s Department of Clinical Pharmacy; Sara Campbell, in Thomas Jefferson University’s Department of Obstetrics and Gynecology; and Nelly Mugo, Jessie Kwatampora, Michael Chitwa, Joshua Kimani and Anne Gakure, all with the Kenyatta National Hospital/University of Nairobi in Nairobi, Kenya.