To create episodes of care, Symmetry inputs service-level records with each input record containing information on a single service item and up to four diagnoses per record. These records also include data on dates of service. Services are always identified on an institutional claim (IP, OP, SNF, HH and HS claims) by a revenue center code, and if there are HCPCS/CPT codes on a claim, each always corresponds to single revenue center code. So in creating service-level inputs from institutional claims, we use a single revenue center code as the principal designator of the service and include procedure codes when present. A service record from an institutional claim also includes up to the first four diagnosis codes listed on parent record38 For non-institutional services, Medicare's PB and DME claims are readily separated into line items associated with individual HCPCS or CPT codes; these claim types have no revenue center codes. Each input record constructed from a PB and DME claim consists of a single procedure code and its corresponding line-item diagnosis. Consequently, in addition to diagnosis information in a Medicare setting, the ETG grouper primarily relies on revenue center codes to group IP/SNF/HS claims, procedure codes to group PB and DME claims, and it can use either or both types of codes to group OP and HH claims.
In addition to using input files, the user can influence grouping outcomes through a configuration file, which we largely set to Symmetry's default settings. Among the default settings we use is Symmetry's link facility records feature, which connects claims associated with hospital stays into "confinements." We use this feature since Medicare IP claims are not necessarily separate admissions. We also use Symmetry's ETG-specific clean periods and default annual truncation of chronic episodes when creating episodes. We do not, however, use the "summarize complete episodes only" feature as suggested by Symmety's documentation because we want to analyze both incomplete and complete episodes.
With non-institutional claims, the cost of the procedure is identified with each line item, thus there is no ambiguity in assigning the cost of services to episodes. However, costs of services on institutional claims cannot be disaggregated from the Medicare payment for the parent claim. This does not pose a problem when all services from the parent claim are grouped to a single episode, but when the input records of an institutional claim are assigned to two or more episodes, the ETG grouper offers no guidance for how to divide the cost of this claim across its associated episodes. We implement a plurality rule to allocate costs when service-level inputs for a single institutional claim are grouped to multiple episodes. This rule assigns the cost of the institutional claim to the episode that captures the largest number of service-level inputs from the parent record. In the case of a tie, costs are evenly split between episodes.