Cancer-related DAs are effective in increasing patient knowledge compared with usual practice without increasing anxiety particularly in the area of cancer screening. Further research is needed to determine the effectiveness of DAs in the prevention and treatment context.

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The clinical sensitivity of nucleic acid amplification tests may be determined by analytical sensitivity and inhibitors in patient samples. We established endpoints for detection of propagated Chlamydia trachomatis L2 434, diluted according to swab and urine protocols for APTIMA Combo 2 (AC2), ProbeTec ET (PT), and Amplicor (AMP) assays. AC2 was 1,000-fold more sensitive than PT and 10-fold more sensitive than AMP on mock swab specimens. For urine, AC2 analytical sensitivity was 100-fold greater than those of the other assays. Spiking an aliquot of each clinical-trial sample from 298 women demonstrated inhibition rates in first-void urine (FVU), cervical swabs (CS), and vaginal swabs (VS) of 12.1%, 12.8%, and 10.4% for AMP; 27.2%, 2%, and 2%, for PT; and 0.3%, 1.7%, and 1.3% for AC2. Inhibition of our C. trachomatis spike and the PT or AMP amplification controls from the manufacturers showed less than 50% correlation. Using an infected-patient reference standard (a specimen positive in at least two tests or a single test positive in two of three samples) in AC2, the VS identified 68/69 (98.6%) infected women compared to CS (89.9%) or FVU (81.2%). Significantly fewer women were identified by PT (65.2%, 63.8%, and 66.7%) or AMP (65.2%, 59.4%, and 56.5%) with the three specimens. By individual specimen type, AC2 confirmed virtually all PT-and AMP-positive specimens, but rates of AC2 confirmation by AMP or PT ranged from 62.9 to 80.3%. The AC2 test identified significantly more women infected with C. trachomatis (P ‫؍‬ 0.001). Vaginal swabs appear to be the specimen of choice for screening.Chlamydia trachomatis is one of the most common sexually transmitted infections in the United States and worldwide (17), largely due to high rates of asymptomatic infection in the lower genital tracts of women and men (24). Early diagnosis followed by treatment of this infection can prevent upper genital tract infection, such as pelvic inflammatory disease (21).For the past 10 years, a great deal of research has led to the development and evaluation of sensitive and specific diagnostic tests for C. trachomatis. These newer nucleic acid amplification tests (NAATs) have been commercialized and are now in routine use in many parts of the world. The important aspect of these assays is their capacity to be used on less invasive specimens, such as vaginal swabs (VS) and first-void urine (FVU), which can be self-collected. Studies have shown that NAATs performed on these less invasive samples are able to detect as many or more infected patients than traditional swabs from the urethra or cervix (2-4, 6-10, 19-22, 25-27, 31).The analytical sensitivity of each test and its susceptibility to inhibitors in different specimen types may determine the clinical sensitivity of each test. We compared detection thresholds and determined the inhibitor and infection rates in three different specimens from 298 women by using three commercial assays for C. trachomatis. MATERIALS AND METHODSSpecimens. Three cervical swabs (CS), three VS, and the first 3...