Study of housing instability ICD-10 codes a call to arms for improved capture of social determinants of health

By Brian Murphy

Z59 and other social determinants of health (SDOH) are difficult to capture in ICD-10. How are you doing it?

A recent study published in the Journal of the American Medical Association (JAMA) demonstrated that housing instability, as captured with the Z59 series, is not being accurately assigned. At all.

The JAMA study stated that patients who met inclusion criteria for housing instability only had an associated ICD-10 code captured 28% of the time. The other 72% had no code assigned or were miscoded.

Most coders are generally held to something resembling a 95% accuracy rate.

This study strikes me as very substantial, following more than 14,500 patients across seven healthcare organizations. The data is in, and it says we have to get better at capturing SDOH. For many reasons.

As a reminder several Z59 series codes are about to become complication/comorbidities (CC) and thus impact IPPS payment. The 2025 IPPS final rule increased the severity designation of the following from non-CCs to CCs, effective Oct. 1:

• Z59.10, Inadequate housing, unspecified

• Z59.11, Inadequate housing environmental temperature

• Z59.12, Inadequate housing utilities

• Z59.19, Other inadequate housing

• Z59.811, Housing instability, housed, with risk of homelessness

• Z59.812, Housing instability, housed, homelessness in past 12 months
• Z59.819, Housing instability, housed unspecified

Z59 and other SDOH have always indirectly impacted physician/profee payment as they can be counted in E/M determination. Thanks to Erica Remer for that reminder (see ICD-10 article below, which includes some important compliance reminders). Some quality models already weight these codes, too.

The issue is bigger than just Z59. The industry does not seem geared to capture SDOH in general. But it’s time to change. Last year homelessness was added as a CC. More codes are being added all the time. We’ve got new codes for insufficient healthcare coverage (Z59.71) and Insufficient welfare support (Z59.72). Not CCs yet, but I wouldn’t be surprised if they were, soon (as long as CMS has the data to support separate payment—more incentive to get them coded).

Per the JAMA study people experiencing housing instability, which comprises homelessness and other unstable housing circumstances, are at high risk for poor health outcomes.

I welcome these changes as it moves medicine from reactive to proactive, even though some feel it is expanding the mission of hospitals too far, from acute care medicine into lifestyle counseling.

We have pretty liberal policies on coding SDOH, per the Official Guidelines for Coding and Reporting. I cited these in the references below. But good workflows are still required, as well as training and education.

How is your organization at capturing SDOH? Is it a focus, or something you have on your 2025 roadmap?

References

• Per the ICD-10-CM Official Guidelines for Coding and Reporting, SDOH code assignment “may be based on medical record documentation from clinicians involved in the care of the patient who are not the patient’s provider since this information represents social information, rather than medical diagnoses. For example, coding professionals may utilize documentation of social information from social workers, community health workers, case managers, or nurses, if their documentation is included in the official medical record. Patient self-reported documentation may be used to assign codes for social determinants of health, as long as the patient self-reported information is signed-off by and incorporated into the medical record by either a clinician or provider.”
• JAMA Network, Accuracy of ICD-10 Diagnostic Codes for Identifying Housing Instability: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2821954#google_vignette
• ICD-10 Monitor, “SDoH: At the Intersection of Lifestyle and Patient Care”: https://icd10monitor.medlearn.com/sdoh-at-the-intersection-of-lifestyle-and-patient-care/