Using Social Determinants of Health ICD-10 Z-codes to Identify Non-Medical Factors among Asthma Hospitalizations in the United States, 2016-2022

Objectives: Healthcare data can reveal actionable opportunities to prevent asthma hospitalizations. Limited national-level data exist regarding social determinants of health (SDOH) and asthma hospitalizations. We examined SDOH-related International Classification of Diseases, Tenth Revision (ICD-10) Z-codes in national administrative data on asthma hospitalizations and described patient- and hospital-level characteristics associated with documented SDOH Z-codes. Methods: Pooled cross-sectional analysis of 2016-2022 Nationwide Inpatient Sample for 200,452 U.S. hospitalizations (all ages) with a primary diagnosis of asthma. Presence of SDOH Z-codes (codes Z55-Z65) assessed by descriptive statistics and multivariable logistic regression to calculate odds ratios (ORs) and 95% confidence intervals (95% CIs) for associations between SDOH Z-codes and patient- and hospital-level characteristics. Results: In unweighted analyses, 3,149 asthma hospitalizations had SDOH Z-codes (1.57%). The most common SDOH Z-codes were homelessness (Z59.0; n=942) and unemployment (Z56.0; n=349). Weighted chi-square analyses found all selected variables were associated with asthma hospitalization SDOH Z-code documentation. Logistic regression results varied; adjusted odds for SDOH Z-code documentation were higher for asthma hospitalizations involving male patients (aOR=1.51; 95% CI, 1.39-1.63; P < .001) compared to female patients. Asthma hospitalizations involving rural hospitals had lower odds of SDOH Z-codes documentation (aOR=0.57; 95% CI, 0.47-0.70; P < .001) compared to urban teaching hospitals. Conclusions: National 2016-2022 data indicate housing- and employment-related Z-codes were the most commonly documented SDOH within asthma hospitalizations. Future analyses could consider establishing causality and exploring how relationships between these SDOH may be used by public health practitioners and others to improve program interventions.