Influence of a vertically integrated care system on mortality risks in insured patients by socio-economic status.

Abstract

e13560 Background: Vertically integrated health care delivery systems may help reduce disparities in cancer outcomes due to socioeconomic status by providing coordinated, comprehensive care. Kaiser Permanente Southern California (KPSC), a large integrated healthcare organization serving more than 5 million patients in Southern California, offers an opportunity to assess whether diagnosis within this system is associated with lower mortality particularly for individuals from lower socioeconomic status (SES) groups. Methods: We analyzed 416,574 insured adult cancer patients diagnosed with invasive malignancies in Southern California between January 1, 2015 and December 31, 2021, from the California Cancer Registry, with follow-up through December 31, 2022 to assess all-cause mortality. Patients with in situ cancers were excluded. Patients were categorized by site of diagnosis: Kaiser Foundation Hospitals (KFH) vs. non-KFH hospitals. Mortality rates were calculated overall as deaths per 1000 person-years (d/1000PY) with 95% confidence intervals (95% CI) and by geocoded SES quintile. Cox proportional hazards models adjusted for age, sex, race/ethnicity, SES, county, insurance type, and stage at diagnosis to estimate the association between diagnosis at healthcare setting and overall mortality risk among KFH and non-KFH hospitals by SES quintile. Results: Overall mortality rates were lower among patients diagnosed in KFH hospitals compared with non-KFH hospitals 87.4 deaths per 1,000 person-years (d/1000PY) (95% CI: 86.3, 88.4) vs. 103.1 d/1000PY (95% CI: 102.4, 103.8). Mortality rates for KFH versus non KFH by SES quintiles were: highest 77.8 d/1000PY (95% CI: 75.4, 80.3) vs. 75.0 d/1000PY (95% CI: 73.8, 76.3), mid-high 82.6 d/1000PY (95% CI: 80.5. 84.6) vs. 92.4 d/1000PY (95% CI: 91.0, 93.7), mid 89.5 d/1000PY (95% CI: 87.4, 91.7) vs. 109.3 d/1000PY (95% CI:107.6, 110.9), mid-low 92.6 d/1000PY (CI: 93.3, 99,2) vs. 125.3 d/1000PY (CI: 123.4, 127.3), and lowest 96.2 d/1000PY (95% CI:93.3, 99.2) vs. 140.8 d/1000PY (95% CI:138.4, 143.2), respectively. Mortality risks were lower amongst KFH patients after multivariate adjustment (non-KFH, ref) HR = 0.83 (95% CI 0.82, 0,84). Stratified hazard ratios by SES quintiles: highest 0.97 (95% CI: 0.94, 1.0), mid-high 0.86 (95% CI: 0.84, 0.88), mid 0.82 (95% CI 0.79, 0.84), mid-low 0.78 (95% CI 0.76, 0.81), and lowest 0.72 (95% CI 0.69, 0.71). Conclusions: Diagnosis in a vertically integrated health system was associated with lower all-cause mortality rates, with the greatest benefit observed among patients in the lowest SES quintile (28% mortality reduction). These findings suggest that integrated healthcare systems can mitigate mortality risks amongst socioeconomically disadvantaged patients.