Tuesday, October 6, 2015

Exact Sciences (EXAS) Fails to Impress U.S. Preventative Task Force (USPTF), EXAS Shares should Slide...

mtsDNA (Stool DNA Plus FIT)

The mtsDNA test (Cologuard®), concurrently approved by the FDA for marketing and by CMS for coverage in August 2014, combines the results of a FIT and DNA marker assays. It is the most expensive of stool tests, reimbursed by CMS at $493 per test.307 In comparison, the cost of FITs is generally much lower, with a CMS reimbursement of $23 and a mean commercial reimbursement of $21 per test.308 In one large study (n=9989), mtsDNA was statistically significantly more sensitive for CRC at 92.3 percent than OC FIT-CHEK (73.8 percent) using a recommended single stool sample for each test. In other included FIT studies, OC FIT-CHEK had higher estimated sensitivity than observed in this study, when multiple samples or lower assay cutoff was used. However, comparison of test performances across studies is difficult due to differences in study design and population characteristics. In all cases, increasing sensitivity was accompanied by decreasing specificity. Specificity for the mtsDNA test (84.4 percent), for example, was lower than all FIT assays, resulting in the highest false positive rate

The high rate of unsatisfactory samples for the mtsDNA test (6.25 percent) was concerning when compared to these rates for FITs (0.3 percent). Excluded samples in this study were in part due to leakage in shipping, which the manufacturer reported has since been fixed, as well as a study quality control measure that authors indicate would not be encountered in clinical practice.166 At a programmatic level, information is lacking on patient adherence and the appropriate screening interval, as well as the impact of false positives as a result of lowered specificity.


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