Introduction
This document details the methodology for the Revascularization for Lower Extremity Chronic Critical Limb Ischemia measure and should be reviewed along with the Revascularization for Lower Extremity Chronic Critical Limb Ischemia Measure Codes List file, which contains the medical codes used in constructing the measure.
Measure Description
Episode-based cost measures represent the cost to Medicare for the items and services provided to a patient during an episode of care (“episode”). In all supplemental documentation, “cost” generally means the standardized1 Medicare allowed amount,2 and claims data from Medicare Parts A and B are used to construct the episode-based cost measures.
The Revascularization for Lower Extremity Chronic Critical Limb Ischemia episode-based cost measure evaluates a clinician’s risk-adjusted cost to Medicare for patients who undergo elective revascularization surgery for lower extremity chronic critical limb ischemia during the performance period. The measure score is the clinician’s risk-adjusted cost for the episode group averaged across all episodes attributed to the clinician. This procedural measure includes costs of services that are clinically related to the attributed clinician’s role in managing care during each episode from 30 days prior to the clinical event that opens, or “triggers,” the episode through 90 days after the trigger.
Measure Rationale
Roughly 6.5 million people age 40 and older in the United States are affected by Peripheral Vascular Disease (PVD), and the total costs from PVD in the United States are around $21 billion annually.3 Surgeries associated with Revascularization for Lower Extremity Chronic Critical Limb Ischemia are fairly common, and there are significant opportunities for improvement in care for this patient population. The Revascularization for Lower Extremity Chronic Critical Limb Ischemia episode-based cost measure was selected for development based on input from an expert clinician committee—the Peripheral Vascular Disease Management Clinical Subcommittee—because of its impact in terms of patient population and clinician coverage, and the opportunity for incentivizing cost-effective, high-quality clinical care in this clinical area. Subsequently, members of the Clinical Subcommittee provided extensive, detailed input on this measure.
Measure Numerator
The cost measure numerator is the sum of the ratio of observed to expected4 paymentstandardized cost to Medicare for all Revascularization for Lower Extremity Chronic Critical Limb Ischemia episodes attributed to a clinician. This sum is then multiplied by the national average observed episode cost to generate a dollar figure.
Measure Denominator
The cost measure denominator is the total number of episodes from the Revascularization for Lower Extremity Chronic Critical Limb Ischemia episode group attributed to a clinician.
Data Sources
The Revascularization for Lower Extremity Chronic Critical Limb Ischemia cost measure uses the following data sources:
- Medicare Part A and B claims data from the Common Working File (CWF)
- Enrollment Data Base (EDB)
- Long Term Care Minimum Data Set (LTC MDS)5
Care Settings
Methodologically, the Revascularization for Lower Extremity Chronic Critical Limb Ischemia cost measure can be triggered based on claims data from: ambulatory surgical centers (ASC), hospital outpatient departments (HOPD), and acute inpatient (IP) hospitals.
Cohort
The cohort for this cost measure consists of patients who are Medicare beneficiaries enrolled in Medicare fee-for-service and who undergo elective revascularization surgery for lower extremity chronic critical limb ischemia that triggers a Revascularization for Lower Extremity Chronic Critical Limb Ischemia episode.
The cohort for this cost measure is also further refined by the definition of the episode group and measure-specific exclusions (refer to Section 4).
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1 Claim payments are standardized to account for differences in Medicare payments for the same service(s) across Medicare providers. Payment standardized costs remove the effect of differences in Medicare payment among health care providers that are the result of differences in regional health care provider expenses measured by hospital wage indexes and geographic price cost indexes (GPCIs) or other payment adjustments such as those for teaching hospitals. For more information, please refer to the “CMS Part A and Part B Price (Payment) Standardization - Basics" and “CMS Part A and Part B Price (Payment) Standardization - Detailed Methods” documents posted on the CMS Price (Payment) Standardization Overview page. (https://resdac.org/articles/cms-price-payment-standardization-overview).
2 Cost is defined by allowed amounts on Medicare claims data, which include both Medicare trust fund payments and any applicable beneficiary deductible and coinsurance amounts.
3 CDC. “Peripheral Arterial Disease (PAD) Fact Sheet.” https://www.cdc.gov/heartdisease/PAD.htm
4 Expected costs refer to costs predicted by the risk adjustment model. For more information on expected costs and risk adjustment, please refer to Section 4.5.
5 For information on how LTC MDS data are used in risk adjustment, please refer to Section 4.5.