Post-Acute Care Episodes Expanded Analytic File. 2.4 Diagnosis and Severity Adjustment


RTI ran each of the claims initiating episodes through the most recently available 3M Medical Severity Grouper (MS-DRG) software version 27.0. For episodes initiating with an acute hospitalization or an LTCH claim, this allows for consistent comparison of MS-DRGs over time.

Given the analysis of "community entrant" episodes, a different approach was required for HHA- and IRF-initiated episodes by condition. The primary diagnoses on IRF claims are vague and generally not descriptive of the underlying condition for which a patient is receiving care, and HHA claims most often use V-codes to describe the types of services being received.

For IRF-initiated episodes, RTI stratified analyses by the rehabilitation impairment group (RIC) recorded on the IRF claims in the standard analytic file (SAF). RICs represent 21 groups of conditions for which a beneficiary is treated and are the basis for payment for IRFs. Examples of RICs include stroke, neurologic conditions, cardiac, pulmonary, spinal cord dysfunction, brain dysfunction, and amputation.

For HHA-initiated episodes, RTI used a condition grouping algorithm based on Major Diagnostic Category (MDC) and MS-DRGs after running the MS-DRG grouper on all claims including HHA claims. These groupings are highly aggregated but provide an understanding of the broad types of cases entering HHA without a prior acute hospitalization. These groupings are presented in Section 4. In addition, RTI also examined International Classification of Diseases Ninth Revision (ICD-9) coding in the first position of HHA claims and the home health resource group (HHRG) codes recorded on HHA claims for payment purposes. These groups do not reflect specific diagnosis groups but include measures of therapy utilization, clinical severity, functional severity, and service severity.

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