ICD-10 codes for SDOH, housing instability miss the mark

ICD-10 codes designed for documenting housing insecurity aren't effectively flagging patients who self-report experiencing this social determinant of health, according to a new JAMA Network Open study.

The study, published as a research note, showed that patient records only showed the correct ICD-10 code for housing insecurity about a quarter of the time. Most of the time, patients self-reported housing insecurity, but their clinicians screening for SDOH did not record the ICD-10 housing insecurity code.

ICD-10 codes specific to SDOH are key for helping hospitals and health systems track which patients might experience certain social factors. The ICD-10 uses the Z59 diagnostic code to document patients screening positive for housing insecurity, which includes homelessness and other unstable housing circumstances.

In short, using these ICD-10 codes is critical documentation intended to guide health system population health efforts.

But this latest study, which looked at patients from a Chicago-based Health Care for the Homeless Program, showed that the Z59 code is not always being used correctly. Using patient self-reports of housing insecurity as the baseline, the researchers found the Z59 code is being used wrong more than 70% of the time.

The assessment included more than 14,000 adult patients. Of those patients, 28% self-reported housing instability and had a Z59 code, and in 0.2% of cases, patients did not self-report housing instability, nor did they have a Z59 code for it. This means these patients were documented correctly.

But in 71% of cases, patients self-reported housing instability but did not have a Z59 code, meaning these patients were slipping through the health system's cracks. In 0.5% of cases, patients did not self-report housing instability, but they had a Z59 code.

Z59 codes had a 28.2% sensitivity and 30.4% specificity, indicating poor overall performance.

These findings warrant closer inspection, the researchers said, because of the impact Z59 codes can have on hospital operations and SDOH interventions. Moving forward, investigators might consider examining the factors that would lead a healthcare provider to assign a Z59 code to a patient during a clinical encounter.

Importantly, reimbursement is not at risk with these ICD-10 codes. Hospitals and health systems primarily use them to guide population health and SDOH interventions. However, accurate documentation is critical for appropriate and judicious use of resources, the researchers concluded.

Sara Heath has covered news related to patient engagement and health equity since 2015.