OBJECTIVES: Little is known about invasive E. coli disease (IED) among high-risk populations such as older adults (³65 years). This study aims to describe patient characteristics and clinical and economic burden of IED among Medicare patients.

METHODS: The IED cohort included Medicare patients who had diagnosis codes indicating IED identified in RWD Insights, an all-payers claims database, from 01/2018-12/2018. Patients were required to have ≥12 months continuous data before/after first IED diagnosis (index date). Preliminary propensity score matching (PSM) was used to match non-IED patients to the IED patients according to selected demographic and clinical characteristics with further evaluation and validation of diagnosis categories used in PSM ongoing. Cox proportional hazards model was used to evaluate time to all-cause mortality, and generalized linear models were used to examine healthcare costs (per patient per year) and utilization (per patient per year) vs. matched controls.

RESULTS: IED cohort (n=32,247) was older (76.7 vs. 74.2, p<0.0001), included more females (62.7% vs. 57.1%, p<0.0001), and had higher Charlson Comorbidity Index score (3.6 vs. 1.1, p<0.0001) compared to non-IED cohort (n=283,779). 83% (n=26,671) of IED patients received inpatient care, with 29% (n=7,634) treated in ICU. Post-PSM (n=29,041), IED patients vs. non-IED, had significantly higher HCRU and total costs ($14,495 vs. $1,988, p<0.0001), driven primarily by higher number of inpatient visits (8.1 vs. 3.4, p<0.0001) and higher inpatient costs ($13,104 vs. $2,780, p<0.001). After index date, proportion of patients that died was significantly higher among IED cohort (26.3% vs. 9.5%; p<0.0001). Adjusted hazard ratio for all-cause mortality in IED cohort when compared with non-IED cohort was 2.84 (CI: 2.72, 2.97, p<0.0001).

CONCLUSIONS: These findings highlight the substantial burden of IED among older adults when compared with matched controls and the need for novel preventive and treatment strategies to mitigate poor outcomes.