National patterns in the use of International Statistical Classification of Diseases and Health Related Problems, tenth revision Z codes in ambulatory surgery from 2016 to 2019

In the tenth revision of the International Statistical Classification of Disease and Health Related Problems (ICD-10), Z codes were added to improve documentation and understanding of health-related social needs. We estimated national Z code use in the ambulatory surgery setting from 2016 to 2019. Using the Nationwide Ambulatory Surgery Sample (NASS), we identified encounters for ambulatory surgery with an ICD-10 code between Z55.0 and Z65.9. Data were stratified by Z code domains from the Centers for Medicare and Medicaid Services (CMS). This analysis of 41,827 ambulatory surgery encounters with documented Z codes found that the most documented determinants of health related to multiparity or unwanted pregnancy, homelessness, and incarceration. There was a 16.1% increase in the use of Z codes from 2016 to 2019. Rates of Z code use in the ambulatory surgery setting are increasing with current documentation serving as a specific but not sensitive measure of socioeconomic need.