Identifying homelessness in Medicaid claims: a mixed-methods approach
Creators: name: Enich, Michael
Publisher: name: No Publisher Supplied
Year: 2023

description: The association of the claims-based ICD-10 Z code for homelessness (Z59.0) with documented history of homelessness service use is unknown. This study examined the concordance of the Z59.0 code in Medicaid claims with homelessness service use recorded in the Homeless Management Information System (HMIS) among Medicaid beneficiaries in 19 New Jersey counties. Using an explanatory sequential mixed methods design, the overall aim of this project was to explain patterns in the use of the ICD-10 Z code for homelessness (Z59.0) in Medicaid claims. The primary research questions were as follows: 1.What is the prevalence of the Z59.0 code for homelessness on hospital inpatient and emergency department claims records, and does it vary by population characteristics and/or known homelessness status?2.What demographic, clinical, and utilization characteristics are associated with a claim being Z-coded? 3.How do hospital providers understand the use of Z codes in the context of social determinants of health assessment?4.What are providers’ explanations for the patterns and prevalence of Z codes in Medicaid claims? I utilized an explanatory sequential mixed methods approach (QUANT  qual), first using positive predictive value (PPV) and kappa coefficients to assess the degree of concordance between inpatient and emergency department (ED) claims-based, Z-coded status and documented homelessness service use in HMIS. I employed nested binary logistic regression models to predict odds of Z-coded homelessness status. Quantitative analysis then informed qualitative pragmatic semi-structured interviews, which I conducted with inpatient and ED physicians (n = 18) to understand the use of Z codes in the context of social determinants of health assessment and prescribers’ explanations for the patterns and prevalence of Z codes in Medicaid claims. I analyzed interviews using cross-case deductive and inductive content and cross-case thematic analysis.Sensitivity, PPV, and kappa of Z-coded status were poor overall, although homeless service use histories were significantly associated with higher odds of being Z-coded. Male sex, age over 60 years, and Medicaid expansion eligibility were all associated with higher odds of being Z-coded. Substance use disorders (SUD) and severe mental illnesses (SMI) had the strongest associations with the presence of a Z59.0 code. Wide variation in use of Z-codes across hospitals was evident. Qualitative interviews revealed an idiosyncratic process by which providers screen for social determinants of health and integrate them into clinical encounters, with no explicit role for Z coding in this process. When they were used, it was potentially inadvertently and as part of documenting complexity to seek higher reimbursement. Participants could not confidently speak to how Z codes are added to final claims or describe hospital-level social determinants of health interventions. The physicians thought Z-coding prevalences were largely consistent with the homeless population, with the exception of race/ethnicity and hospital-level Z coding practices. They suggested nuances within the homelessness designation not reflected in concordance analysis, such as that Z-coded individuals are homeless even if they do not use homeless services, which implies that individuals enrolled in permanent supportive housing (PSH) are not homeless. They also suggested providers could still meaningfully address the homelessness of those who are not Z-coded but have used homeless services.Analysis of linked Medicaid and HMIS data revealed limited concordance between Z-coded claims status and known homelessness service utilization. Notable factors associated with homelessness consistent with participant expectations contributed to higher odds of being Z-coded, including homelessness service use category, male sex, and diagnosis of SUD and SMI. The lack of systematic use of Z codes for homelessness this study observed is problematic because it limits the codes’ usefulness in planning or implementing strategies to address homelessness. As internationally standardized tools, these codes represent an opportunity to consistently document multiple social determinants of health (including homelessness) across settings. Doing so would allow for assessment of local needs, monitoring of interventions to address them, and a broader view of population-level social determinants of health. Hospital or state policy could drive their use, and national billing changes suggest an opportunity to increase reimbursement for considering these needs.