On October 22, 2009, CMS Is hosting a national provider call on the Outcome and Assessment Information Set (OASIS-C). OASIS-C is the first major update to the data set that home health agencies must collect in order to participate in Medicare. Changes to the OASIS include significant revisions to existing items and the addition of items that measure the processes of care. Transition to OASIS-C is scheduled to occur January 1, 2010. Registration is required by October 21.