I often begin my day with an environmental scan. Last week, an article from Becker’s Clinical Leadership caught my eye, “Hospital mortality, infectionrates improve despite rising acuity: 3 findings.” The article cites a report
from Vizient that analyzes data from more than 1,000 hospitals comparing trends from fourth quarter 2019 to the second quarter of 2025 “across the measures of acuity, mortality performance and select hospital-acquired
conditions.” The analysis included the following data points:
- Patient acuity increased by 5% between 2019 and 2025 as measured by an increase in hospital case mix indexes from 1.71 to 1.80.
- The mortality index decreased 33% from 0.97 in 2019 to 0.65 in 2025.
Sadly, though, the conclusion drawn from these results is “improvement in clinical reliability, care processes and operational discipline.”
Yes, I believe there may have been some improvement in these areas, but my experience is that shifts in these metrics are also attributable to the efforts of CDI and coding professionals. I have firsthand experience as a
former CDI manager and consultant helping CDI and coding departments achieve this type of success.
The goal of all CDI departments tasked with addressing hospital mortality rates is to increase the expected mortality rate as high as possible to offset actual deaths. For example, a rise in case mix index with the same volume of deaths will still result in a decrease in the mortality index because this is a ratio. Greater reductions can be achieved if one or two fewer patients expire due to improved clinical reliability and care processes, but increasing the expected mortality rate will have a more dramatic effect than one less death. It is not surprising that both CMI has increased and mortality indexes have decreased as CDI and coding professionals become more proficient at understanding the relationship among documentation, coding practices, MS-DRGs and the mortality index.
It sounds great to say the Medicare population is experiencing better outcomes even though they are sicker compared to earlier populations, but I am not sure the referenced data (CMI and mortality index) is the best way
to make that determination. There are some flaws with defining patient acuity solely on case mix index, which is the average of the relative weights associated with either billed or paid claims based on MS-DRG methodology
for a specified period of time. In discussing the development of MS-DRGs, the reference document states, “The term case mix complexity is used to refer to an interrelated but distinct set of patient attributes which include
severity of illness, prognosis, treatment difficulty, need for intervention and resource intensity. . . When clinicians use the notion of case mix complexity, they mean that the patients treated have a greater severity of illness, present greater treatment difficulty, have poorer prognoses and have a greater need for intervention . . . On the other hand, administrators and regulators usually use the concept of case mix complexity to indicate that the patients treated require more resources which results in a higher cost of providing care . . . Therefore, a hospital having a more complex case mix from a DRG perspective means that the hospital treats patients who require more hospital resources but not necessarily that the hospital treats patients having a greater severity of illness, a greater treatment difficulty, a poorer prognosis, or a greater need for intervention.”
For the sake of argument, it may be helpful to review other data that points toward a higher acuity Medicare population, an increase in the incidence and number of chronic conditions in the Medicare population. This is
evident through a variety of resources like the Chronic Conditions Data Warehouse that tracks Medicare data. These Centers for Disease found that almost 93% of adults aged 65 and older in 2023 reported having at
least ≥ 1 chronic condition, a rate that has steadily increased since 2013. However, we must consider this data in the light of the fact that Medicare Advantage (MA) organizations deliver more healthcare to Medicare
beneficiaries than Medicare Fee-for-Services (traditional Medicare) as the volume of enrollees in MA plans has reached 55% of all eligible Medicare beneficiaries. The reimbursement methodology associated with the MA
program is based on diagnoses within the CMS Hierarchical Condition Categories (CMS-HCCs), which are primarily chronic disease because it is payment is made based on diseases that are expected to require
healthcare resources in the following year. A study published by the Annal of Internal Medicine found, “differences in diagnosis and coding practices, rather than disease burden, may be driving higher payments to MA plans.
I very much respect Vizient and KaufmanHall, the authors of the report on which the referenced article was based. However, this report demonstrates that perspective is everything and there is still more work to be done as the work of CDI is still often misunderstood within the healthcare industry.
