If you're thinking about switching from one CERT to another within the same year, this will be important for you when attesting:
"Q: “If we attest for 2011, then 3-4 months into 2012 we change to another software vendor, is there a way to attest using both software vendors since we have to combine or run reports to attest for the whole year of 2012?”
A: Yes, you can attest using both EHRs—in fact, you must report from both EHRs. First, enter both certified complete EHRs into the Certified Health IT Product List (CHPL) website to generate a new EHR Certification ID number to use for 2012 attestation. You will need to combine the results, measure by measure including clinical quality measures, from the two sets of reports that you run. For measures that require a count of actions, this is fairly easy—you simply add the numerators and denominators. Where this becomes somewhat challenging is in reporting measures where the denominator is “unique patients.” According to a CMS FAQ regarding a similar situation, (i.e., providers who see patients in multiple locations with different certified EHRs), “…it is the responsibility of the EP….to reconcile information from multiple certified EHR systems in order to ensure that each unique patient is counted only once for each objective.” No further guidance is provided on how to accomplish that."