Comorbidities, Utilization, and Quality of Care as Predictors of Diabetes Complications

Objective: To determine factors associated with diabetes complications, measured by the Diabetes Complications Severity Index (DCSI). Research Design and Methods: This longitudinal analysis used insurer data (2016 - 2020) and included Medicare Advantage beneficiaries aged 65 and older with type 2 diabetes. The dependent variable was DCSI. Independent variables included year, demographics (age, sex, race/ethnicity, language, dual eligibility, rurality), comorbidities (Charlson (CCI) and Functional Comorbidity Indexes (FCI)), utilization (risk adjustment scores, emergency department, urgent care, outpatient, physician, inpatient, and pharmacy claims), and quality measures (hemoglobin A1c and blood pressure control). Four multilevel mixed-effects models were developed: demographics (model 1), comorbidities (model 2), utilization (model 3), and quality measures (model 4). Results: We included 49,843 individuals. Model 1 showed a relationship between year (IRR=1.32, p<0.001, 2020 vs. 2016), sex (IRR=0.86, p<0.001, female vs. male), race/ ethnicity (IRR=1.06, p<0.001, Black vs. white), dual eligibility (IRR=1.26, p<0.001 yes vs. no), and rurality (IRR=0.90, p<0.001, yes vs. no). CCI (IRR=1.18, p<0.001) and FCI (IRR=1.08, p<0.001), which share overlapping and distinct comorbidities with DCSI, were associated with higher DCSI. Emergency department visits (IRR=1.01, p<0.05) and physician visits (IRR=1.003, p< 0.05) were associated with higher DCSI. Not meeting the blood pressure quality measure was linked to higher DCSI (IRR=1.10, p<0.05), while hemoglobin A1c control was not. Conclusions: Year, male sex, race/ethnicity, non-rural status, comorbidities, emergency department visits, and not meeting the blood pressure measure were linked to higher DCSI. Future research should develop strategies for high-risk groups in primary care settings.