Explanation: CMI is a metric that reflects the diversity, complexity, and severity of the patients treated at a healthcare facility, such as a hospital. CMI is used by CMS to determine hospital reimbursement rates for Medicare and Medicaid beneficiaries. CMI is calculated by adding up the relative MS-DRG weight for each discharge, and dividing that by the total number of Medicare and Medicaid discharges in a given month and year. Higher CMI values indicate that a hospital has treated a greater number of complex, resource-intensive patients, and the hospital may be reimbursed at a higher rate for those cases.
However, CMI is not the best measure of CDI performance, because it is influenced by many factors beyond CDI efforts, such as patient population, coding accuracy, documentation specificity, patient comorbidities, high volumes of highly weighted DRGs, and annual updates to relative MS-DRG weights. Therefore, measuring CMI over time with a focus on particular documentation improvement areas in addition to the overall CMI can provide a more comprehensive and meaningful assessment of CDI performance. For example, CDI programs can track CMI changes for specific DRGs, clinical conditions, or service lines that are targeted for documentation improvement initiatives. This can help identify the impact of CDI interventions on documentation quality, accuracy, and completeness.
A. Over time with a focus on high relative weight (RW) procedures that impact these procedures on overall CMI. This is not the best way to measure CMI as a metric of CDI performance, because it may not reflect the true complexity and severity of the patients treated at the facility. Focusing only on high RW procedures may overlook other documentation improvement opportunities for lower RW procedures or medical cases that may also affect patient outcomes, quality indicators, and reimbursement.
C. Month-to-month and focus on patient volumes to determine the raise the overall CMI. This is not a valid way to measure CMI as a metric of CDI performance, because patient volumes do not directly affect CMI. CMI is calculated by dividing the total relative weights by the total number of discharges, so increasing patient volumes will not necessarily raise the overall CMI unless the relative weights also increase.
D. Month-to-month to show CMI variability as a barometer of a specific month. This is not a reliable way to measure CMI as a metric of CDI performance, because month-to-month variations in CMI may be due to random fluctuations or seasonal effects that are not related to CDI efforts. Measuring CMI over a longer period of time can provide a more stable and accurate picture of CDI performance.
References:
- CDIP Exam Preparation Guide, 2021 Edition. AHIMA Press. ISBN: 9781584268530
- Case Mix Index (CMI) | Definitive Healthcare
- Q&A: Understanding case mix index | ACDIS
