While there is no shortage of TV shows set in hospitals—from Grey’s Anatomy and Scrubs to Chicago Hope and ER—you’ve probably never seen a drama based in a hospital step-down unit. One of the less flashy areas of the hospital, the step-down unit cares for semi-critical patients who are too sick for the general ward but do not need constant oversight.
But in many ways, the step-down unit is stepping up the quality of care in hospitals, according to new research by Associate Professor Carri Chan, whose work reveals that this understudied part of the hospital can play a critical role in saving lives, shortening lengths of stay, and reducing readmission rates. Given the expense of hospital care, and the fact that intensive care units consume up to 40 percent of all hospital costs, any savings through operational efficiencies would likely be welcome by operators.
“At a high level,” says Chan, “this is a question of how to utilize our resources in a manner to deliver high quality care.”
Intensive care-units (ICUs) typically staff one nurse for every one to two patients, step-down units (SDUs) staff one nurse per three to four patients, and general wards have one nurse for every six patients. While it may appear to be more economical to discharge from the ICU directly to the general ward at first glance, this can have costly implications, as Chan discovered in the research below.
Forthcoming in Management Science, her study “Assessing the Impact of Service Level when Customer Needs are Uncertain: An Empirical Investigation of Hospital Step-Down Units” is based on data drawn from 10 hospitals in California operated by Kaiser Permanente. Authored with Cain Brothers & Company Professor of Healthcare Management Linda Green, Suparerk Lekwijit of the University of Pennsylvania, Lijian Lu of Columbia University, and Gabriel Escobar of Kaiser Permanente, this was the first multi-hospital study to examine the role of a SDU for patients coming from the ICU and emergency department.
A major challenge in such a study is building an econometric model that makes apples-to-apples comparisons. For example, if the ICU only discharges mortally sick patients to the SDU and only sends healthy patients to the general ward, then the SDU could on its face appear to have a high mortality rate.
When the researchers built a model that could amelioriate those biases, they found that availability of SDU care was associated with significant improvements for patients coming from the ICU: the likelihood of in-hospital death dropped 17 percent, patients left the hospital one-third of a day sooner, and readmission to the hospital within two weeks dropped by 8 percent. Across the 10 hospitals, they estimated that SDU care had the potential to annually save 187 lives, 3,096 hospital days, and 137 hospital readmissions.
However, the results were more nuanced for patients coming from the emergency department. While beneficial for low-severity patients, SDU care for high-severity patients from the emergency department would instead lead to annual increases of 71 deaths, 981 hospital days, and 173 readmissions across the hospitals in the study.
Why the difference? Because the SDU is not equipped to take on the most critical of patients, as could happen if it’s seen as an overflow space for all patients in the emergency department. “These more severe patients should be going to the ICU, but if capacity is an issue, they could end up in the SDU instead,” explains Chan.
Chan and her colleagues are now looking to publish their research for a wider medical audience so that other hospitals might potentially benefit from this new understanding of SDUs. These units have been around for decades, but there is no consensus in the medical community about how to use them.
The research builds upon previous work that Chan conducted with Mor Armony and Bo Zhu of New York University. Titled “Critical Care Capacity Management: Understanding the role of a Step-Down Unit,” and published in 2018 in Production and Operations Management, that paper built a queueing model of the ICU and SDU systems and used simulation analysis to tease out conclusions for how to provide optimal care.
The researchers discovered that “one size does not fit all,” Chan says. “Some hospitals may benefit from having an SDU, while quality of care may be negatively impacted by having an SDU at other hospitals.” Factors such as staffing requirements in the ICU versus SDU, as well as the relative cost of care for critical versus semi-critical patients, vary substantially across different hospitals and geographic areas, spurring operators to utilize these units in different ways.
“I don’t think there’s a cookie-cutter message about what should be done,” says Chan, citing differences in the needs of patients coming from intensive care versus from the emergency department. “The findings suggest there is a need to understand these step-down units much better.”
Read the research
About the researcher
Professor Chan teaches the core MBA class, Operations Management. Her primary research interests are in data-driven modeling of complex stochastic systems, dynamic optimization, and...Read more.