Purpose
Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are the 2 most frequently reportable sexually transmitted infections (STIs) in the United States, and Trichomonas vaginalis (TV), although not a notifiable disease, is the non-notifiable disease. most common curable. Viral STIs around the world. Women bear a disproportionate burden of these infections and testing is needed to identify them.
Although vaginal swabs are the recommended type of sample, the most commonly used sample among women is urine. The objective of this meta-analysis was to evaluate the diagnostic sensitivity of commercially available assays for vaginal swabs versus urine samples from women.
Methods
A systematic search of multiple databases from 1995 to 2021 identified studies that (1) evaluated commercially available trials, (2) presented data for women, (3) included data obtained from the same trial on a urine sample and a vaginal swab of the same patient, (4) used a reference standard, and (5) were published in English.
We calculated pooled estimates for sensitivity and corresponding 95% CIs for each pathogen, as well as odds ratios for any differences in performance.
Results
We identified 28 eligible articles with 30 comparisons for CT, 16 comparisons for NG, and 9 comparisons for TV.
Pooled sensitivity estimates for vaginal swabs and urine, respectively, were 94.1% and 86.9% for CT, 96.5% and 90.7% for NG, and 98.0% and 95.1% for TV ( all P values < 0.001).
Figure: Difference in assay sensitivity between vaginal swabs and urine in the detection of Trichomonas vaginalis. OR = odds ratio. a Not calculable due to 100% sensitivity.
Conclusions The evidence from this analysis supports the Centers for Disease Control and Prevention (CDC) recommendation that vaginal swabs are the optimal specimen type for women undergoing testing for chlamydia, gonorrhea, and/or trichomoniasis. |
Discussion
The combined sensitivity of vaginal swabs was consistently higher than that of urine ; however, for Trichomonas vaginalis (TV), the OR of vaginal swabs being more sensitive than urine did not reach statistical significance. Because TV had a small sample size and moderate to high heterogeneity, 16 we were conservative in using a random effects model; however, if a fixed effects model was used, the OR of vaginal swabs being more sensitive than urine was statistically significant.
We must mention the lack of data available for transgender people ; However, it can be postulated that among transgender and gender diverse individuals who engage in receptive vaginal sex, the burden of organisms is likely higher in the vaginal or neovaginal space compared to urine; however, this is an area that needs further research. An additional limitation is that very few studies provided sufficient data to allow us to make separate estimates for symptomatic and asymptomatic women, but it is reasonable to postulate that the sensitivity differential might be greater among asymptomatic women due to lower organism burden.
Since this meta-analysis combines symptomatic and asymptomatic patients, meaning that for some it is a diagnostic test and for others it is a screening test, this would result in a difference in pre-test probability and alter the predictive value. This could potentially alter a doctor’s calculation between accuracy and patient comfort; therefore, stratification by symptom status should be included in future research. Furthermore, most of these data come from clinical studies evaluating assay performance and therefore ensuring adequate urine collection (first catch without urinating within the previous hour). One of the few studies that evaluated midstream clean catch urine compared to first catch urine showed sensitivities of 86.2% and 89.8% (relative to vaginal swabs), respectively. 5
A complete sexual history by physicians is essential to weigh a patient’s comfort level and the risks and benefits of using self-collected or provider-collected vaginal swabs for screening and diagnostic testing. Self-collected vaginal swabs may be preferred, especially for patients with a history of trauma, as the patient may become upset if a provider performs the procedure. Many studies have demonstrated the acceptability and feasibility of self-collected vaginal swabs ; The data strongly supports its use and has done so for decades. Sample collection can, and should, be tailored to individual needs so that patients for whom vaginal sample collection may be a triggering experience can choose to provide urine.
However, based on the large number of studies demonstrating a preference for self-collected vaginal sampling and the data shown here, vaginal sampling should be the initial option offered to patients. The routine use of urine to screen women for CT and NG represents a harm that may have downstream consequences of false negative results and untreated infections. We cannot continue to justify the use of urine except for women for whom collection of a vaginal sample is not acceptable.
Comment The data from Dr. Aarons and his colleagues have given us strong impetus to change our testing practices. Family physicians, pediatricians, and health systems will need to rise to this implementation challenge. As testing technologies advance, this pressure will only grow. Almost all point-of-care STI testing devices, which are beginning to come to market, have validated their platforms on vaginal samples, rather than urine samples. By engaging now in implementation and quality improvement efforts with patients, clinicians, staff, and health systems, we can improve the quality, sensitivity, and reach of adolescent testing and significantly improve adolescent health. |
