Clinical Question: Can a point-of-care test for Chlamydia trachomatis using vaginal swabs be used as an accurate screening test?
The Chlamydia Rapid Test, a point-of-care test that can be read in approximately 30 minutes, has a sensitivity of 83% and a specificity of 99%. Used in higher-risk areas as a screening test, it will rule out Chlamydia infection in 98% of women who don’t have it. It uses vaginal swab samples as an alternative to urine samples, which may be easier to collect. It is certified by the European Union (CE), but not yet available in the United States or Canada. (LOE = 1c)
Mahilum-Tapay L, Laitila V, Wawrzyniak JJ, et al. New point of care Chlamydia Rapid Test — bridging the gap between diagnosis and treatment: performance evaluation study. BMJ 2007;335(7631):1190-1194.
Diagnostic test evaluation
The researchers enrolled 1349 young women attending either a sexual health center or 1 of 2 genitourinary medicine clinics in the United Kingdom to evaluate the Chlamydia Rapid Test. The prevalence of disease ranged from 6% to 9.4% at the 3 sites. The gold standard was first-void urine sample testing by polymerase chain reaction assay and was conducted on all women. For the rapid test, women were given vaginal swabs for self-collection of a sample for analysis. The rapid test result can’t be seen until 25 minutes following preparation of the sample, but can then be read as a simple line on a test strip. The sensitivity of the rapid test was 82.7% and the specificity was 98.8%. The predictive values ranged from 80.6% to 93.8% (positive) and 98% to 99% (negative), depending on the prevalence at each site. A survey found that most (95.9%) women felt comfortable collecting their own vaginal swab specimens and 75% were willing to wait between 30 minutes and 2 hours for their test results.