The federal government indefinitely delayed the start of the controversial radiation oncology model in a final rule published Thursday. 

The Centers for Medicare and Medicaid Services will propose a new start date at least six months in advance under the final rule. CMS proposed the extended delay in April after the agency and Congress pushed its start date back several times. The model was originally slated to roll out Jan. 1, 2021. 

“In light of the fact that it is unknown whether there may be further delays to the [Radiation Oncology] Model that are out of CMS’s control, we believe that the best course of action is to delay the implementation of the RO Model to a future date,” the final rule says. 

The Center for Medicare and Medicaid Innovation, which will manage the mandatory initiative, wants to test whether prospective, site-neutral, episode-based payments for radiotherapy can save money. The innovation center planned to experiment with this approach in a few geographic areas to start. 

But radiation oncologists oppose the model’s current design. Industry and medical groups such as the American Society for Radiation Oncology have asked CMS to redesign it, including by making it voluntary, simplifying the payment methodology and de-emphasizing cost savings.

“The radiation oncology community believes that the model inappropriately prioritizes model savings over healthcare transformation. Radiation oncology episode-based payment bundles alone would be highly transformative, in terms of quality and cost, but CMS’ excessive emphasis on mandating savings has corrupted this promising approach,” the American Society for Radiation Oncology wrote CMS in June. 

The American Society for Radiation Oncology is developing a new alternative payment model proposal, which it aims to complete this year, that would emphasize episodic payment and health equity, the organization said in a statement Thursday.

Federal law requires that CMMI models reduce spending or improve quality. Experimental initiatives cannot be made permanent unless they cut costs without decreasing quality or increase quality without decreasing spending. 

CMS acknowledged in the final rule that provider groups would not support the model without modifications, specifically to the discount factor, which is amount by which the model reduces episode payments to reserve savings for Medicare. But doing so would require CMS to expand the geographic scope of the model, which providers also have advised against.