OBJECTIVES: Beginning in 2015, Z codes were introduced in the ICD-10-CM diagnosis set that allow clinicians to document social determinants of health (SDoH) associated with health status. While Z codes have been integrated into EHRs—and despite the importance of documenting SDoH—Z codes have not been widely adopted by clinicians. The objectives of this study were to document utilization of Z codes across ten broad categories of SDoH and examine the association between patient, clinical, and hospital characteristics and SDoH categories.

METHODS: A descriptive analysis was used to examine Z code diagnoses among adult patients (ages 18+) who were discharged from 1,047 U.S. hospitals with an index visit between January 1, 2016 and December 31, 2021 in inpatient and outpatient settings, using a hospital-based, service level, all-payer, administrative database. All data were statistically de-identified and compliant with HIPAA.

RESULTS: Although use of Z codes was broadly represented across hospitals, overall use of Z codes by clinicians is low with only 4.6% of adults (n=5,406,175) with evidence of any Z code across 117,766,033 patients. Compared to the patient population without Z codes (n=112,359,858), patients with evidence of Z codes were significantly more likely (all χ² p values < 0.0001) to be male (52% vs 42%), younger (72% vs 63% <60 years), single (62% vs 47%), African American (18% vs 14%), and significantly less likely to have commercial insurance (25% vs 42%). The top three Z codes (and corresponding SDoH domains) in order were tobacco use (addictions, n=2.42 million), homelessness (problems related to housing and economic circumstances, n=617,843), and dietary counseling and surveillance (lifestyle behaviors, n=473,638).

CONCLUSIONS: Understanding variation in utilization of Z codes across patient, clinical, and hospital characteristics can be useful for informing increased adoption of Z code use, given the important contribution of SDoH to health outcomes.