Influence of a vertically integrated care system on mortality risks in insured patients by race and ethnicity.

Abstract

e13559 Background: Vertically integrated health care systems may help reduce racial and ethnic disparities in cancer outcomes through coordinated, comprehensive care. Kaiser Permanente, a vertically integrated healthcare system serving approximately 5 million members in Southern California, provides an opportunity to evaluate whether such a system is associated with improved survival rates among insured patients across racial and ethnic groups. Methods: Data were obtained from the California Cancer Registry and included insured adults diagnosed with invasive cancers in Southern California from January 1, 2015 through December 31, 2021, with follow-up through December 31, 2022. Patients with in situ cancers were excluded. Patients (N = 416,574) were categorized by site of diagnosis: Kaiser Foundation Hospitals (KFH) versus non-KFH hospitals. Mortality rates measured as deaths per 1,000 person-years (d/1000PY) with 95% confidence intervals (95% CI) were calculated by race and ethnicity. Cox proportional hazards models were fit separately within each race/ethnicity group, adjusting for age, sex, socioeconomic status quintile, county, insurance type, and stage at diagnosis were used to evaluate the association between diagnosis site (KFH vs. non-KFH) and overall survival. Results: Overall mortality rates were lower in KFH compared with non-KFH hospitals 87.4 d/1000PY (95% CI: 86.3, 88.4) vs. 103.1 d/1000PY (95% CI 102.4, 103.8). Mortality rates by racial/ethnic group for KFH vs. non-KFH were: White 93.6 d/1000PY (95% CI 92.0, 95.1) vs. 100.7 d/1000PY (95% CI 99.8, 101.7), Black 100.7 d/1000PY (95% CI 97.3, 104.2) vs. 136.3 d/1000PY (95% CI 132.7. 140.0), non-White Hispanic 77.7 d/1000PY (95% CI 75.8, 79.6) vs. 106.8 d/1000PY (95% CI 105.2, 108.3), and Asian 76.8 d/1000PY (95% CI 73.9, 79.7) vs. 99.5 d/1000PY (95% CI 97.4, 101.6). Mortality risks were lower amongst KFH patients after multivariate adjustment (non-KFH, ref): White hazard ratio (HR) 0.88 (95% CI 0.86, 0.89); Black HR 0.78 (95% CI 0.75, 0.82); non-White Hispanic HR 0.78 (95% CI 0.75, 0.82); Asian HR 0.77 (95% CI 0.74, 0.81). Conclusions: These results suggest that vertically integrated healthcare systems are associated with lower mortality risks among patients with cancer and ethnic groups with the greatest benefit observed for non-White patients. After adjustment, White patients in the KFH integrated healthcare system were 12% less likely to die during follow-up, while Black, non-White Hispanic, and Asian patients experienced reductions of 22%, 22%, and 23%, respectively compared to their race/ethnicity group counterparts in non-KFH hospitals.