As providers around the country brace for the Oct. 1 conversion to ICD-10 diagnostic and procedural codes, the CMS is reporting positive results from the final round of end-to-end testing of the Medicare claims processing system.

Overall, the CMS reported an 87% acceptance rate on 29,286 claims received.

According to the CMS, 2.6% of the claims were rejected because of invalid submission of ICD-9 codes.

Another 1.8% bounced back because of invalid submission of ICD-10 diagnosis or procedural codes.

Additional errors included incorrect national provider identifiers, health insurance claim numbers, dates of service outside the range valid for testing, etc.

“These types of errors also occurred in the January and April end-to-end testing weeks,” the CMS said in its statement about the results. “Most rejects were the result of provider submission errors in the testing environment that would not occur when actual claims are submitted for processing.”

The CMS also postulated that among the 1,200 or so testers—providers, claims clearinghouses and billing agencies—some of the errors were intentional to make sure the claim would be rejected as part of a regime called “negative testing.”

The testing was conducted between July 20 through July 24.

The results are on the CMS website (PDF).

CMS staff provided an update this afternoon during a conference call for reporters.

“We thought the testing was extremely successful,” said Stacey Shagena, a CMS technical adviser who presented the test results on the call. Problems encountered by CMS contractors in the earlier two rounds of testing this year were fixed and didn’t recur, she said.

Health IT consultant Stanley Nachimson, principal of Nachimson Advisors and an ICD-10 expert, said the pass-through rates in this latest round of testing were “not a significant change” from those of the two earlier sessions. To Nachimson, that proves even more provider testing is needed before Oct. 1.

“Remember, these are people who believe they are ready,” Nachimson said. “And with the errors they (the CMS) are still encountering, it sounds like there are issues in setting up the (providers’) new systems. We don’t know what’s happening to those entities who haven’t prepared or been involved in the testing yet.”

Acting CMS Administrator Andy Slavitt, also speaking on the call, named Dr. William Rogers to the role of ombudsman for the ICD-10 program. Rogers is medical officer for the CMS’ Office of the Administrator and director of the CMS’ Physician Regulatory Improvement Team.

“His role will be to be a one-stop shop for you and to be your internal advocate inside CMS,” Slavitt said.