Admission rates for ambulatory care-sensitive conditions (ACSCs) are often used by health systems as a measure of access to effective primary and preventive care. However, there is debate about whether ACSC admissions primarily reflect social determinants of population health and are largely insensitive to ambulatory care quality. To provide evidence for this debate, this study analyzes adult ACSC admissions of Cook County, Illinois residents to 173 Illinois hospitals from 2016–2018.
Retrospective cohort study.
Hospitalized patients were categorized by sex, by race and ethnicity (Non-Hispanic White, Non-Hispanic Black, Hispanic, Asian, other/unknown), and by primary insurance status (private, Medicaid, Medicare, uninsured, other/unknown) and by whether the admission was on the weekend. Agency for Healthcare Research and Quality Prevention Quality Indicators were calculated to compute ACSC hospitalization rates per 1000 residents across four census data-defined zip code poverty level areas (> 20%, 10-19.99%, 5-9.99% and < 5% poor households). ACSC hospitalization rates were compared to rates for all other medical and surgical conditions across areas. Patient age groups were categorized as 20–44, 45–64, and > 65.
There were 1,384,880 medical and surgical admissions of Cook County Residents age 20 and older from 2016–2018. There were 181,836 (13.3%) admissions classified as ACSC admissions by the overall composite PQI 90. Residents of the highest poverty level zip code area had ACSC rates up to 70% higher than the most affluent zip code area. However, all other medical admissions had a 102% higher rate in the poorest versus most affluent areas, with twice the admission rate for the most severely ill patients (Charlson Score > 3). By comparison, surgical DRG admission rates had only a 6% difference across areas.
These findings indicate that ACSC admission rates mirror other medical, but not surgical, causes of admissions as well as illness severity generally. While socioeconomic differences in access to care undoubtedly exist, use of the ACSC admission rate as a measure of access to primary care may obscure the far more consequential social determinants of chronic illness and hospital use that primarily drive hospital admissions for low income populations.