Study shows effects and costs

Newswise – Six years ago, U.S. hospitals officially gained the ability to document patients’ housing status, including unstable housing and homelessness. The new “Z-codes” reflect an increasing recognition of the role of housing as one of the most important social determinants of health.

A new study using that data reveals huge differences in diagnoses between patients admitted to hospitals with and without housing problems. This includes a sharp divide in the care of mental, behavioral and neurological disorders.

The researchers at the University of Michigan’s Institute for Healthcare Policy and Innovation say their findings demonstrate the importance of better monitoring housing status in healthcare and addressing housing as a social driver of health.

According to the new study published in JAMA network opened by a team led by IHPI scholar Kimberly Rollings, Ph.D. Almost all of these patients were recorded as homeless, although the Z-codes provide 5 different categories of unstable housing.

Overall, 50% of hospital stays for people with documented housing problems were for mental, behavioral and neurological care. That’s 10 times higher than the rate of hospitalizations for these conditions by people who had no housing instability recorded on their chart.

Patients with documented housing instability also had longer hospital stays. On average, they stayed two extra days.

Patients with documented housing instability also accounted for 10% of admission days for mental, behavioral and neurological care. These conditions often require long wait times for beds, so any reduction in length of stay could improve access for all.

The study uses data from the National Inpatient Sample, which includes 20% of all general hospital care, to provide nationally representative estimates of hospital care across all insurance types. The authors used data from 2017 to 2019, when coding for social determinants of health became increasingly common.

Care for hospitalized people with documented housing instability in this sample cost $9.5 billion, of which $3.5 billion was attributed to care for mental, behavioral, and neurological disorders.

Since people with housing problems are far more likely than others to have Medicaid coverage (55%) or no insurance (12%), the majority of those costs likely fall on state programs and hospitals.

Taken together, the authors explain, “Our findings identify the business case for synergistic collaborations between housing, hospital, and mental health experts.”

“Due to the lack of use of Z codes, our findings are probably the tip of the iceberg,” says Rollings. “If we are to improve care for these individuals and make the most of hospital beds, healthcare providers and their institutions must do more to improve screening for this important social driver.”

Rollings is in the Health & Design Research Fellowship Program led by Andrew M. Ibrahim, MD, M.Sc., the study’s lead author. Ibrahim is a surgeon, clinician, scientist, and healthcare design researcher at the Michigan Medicine Department of Surgery.

“This important work led by a housing expert using healthcare data is exactly why we started this Fellowship. We need more interdisciplinary work, such as that led by Dr. Rollings,” Ibrahim said.

The Centers for Medicare and Medicaid Services have more information on using Z codes, as does the American Hospital Association.

In addition to Rollings and Ibrahim, the authors of the new study are Nicholas Kunnath, MS of the Department of Surgery; Caitlin R. Ryus, MD, MPH of Yale University; and IHPI National Clinician Scholar Alexander T. Janke, MD, MHS

Citation: Association of Coded Housing Instability and Hospitalization in the US, JAMA Netw Open. 2022;5(11):e2241951. doi:10.1001/jamanetworkopen.2022.41951

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