By definition, each payer (or at least most payers) will have their own CRD services.  The logic that drives the responses as well as the data available for detecting things like duplicate or contraindicated therapy will be proprietary to that payer.  It's possible that some payers will coordinate and leverage a shared service, but most won't. This imposes no significant cost on EHRs.  EHRs expect to support a wide variety of CDS Hook services - that's sort of the point.  Services can be 'plugged in' to the relevant hooks and all receive the notifications and provide decision support when/if relevant.  In the case of CRD, there will typically only be one or two CRD services called for a given clinical action because the EHR will be required to filter hook calls to only send to payers with whom the patient has active coverage.