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Original Investigation
January 16, 2019

Comparison of Risk-Standardized Readmission Rates of Surgical Patients at Safety-Net and Non–Safety-Net Hospitals Using Agency for Healthcare Research and Quality and American Hospital Association Data

Author Affiliations
  • 1Department of Surgery, Boston Medical Center, Boston, Massachusetts
  • 2Center for Healthcare Organization and Implementation Research, Veterans Affairs Boston Healthcare System, Boston, Massachusetts
  • 3Biostatistics and Epidemiology Data Analytics Center, Boston University School of Public Health, Boston, Massachusetts
JAMA Surg. 2019;154(5):391-400. doi:10.1001/jamasurg.2018.5242
Key Points

Question  After adjusting for hospital characteristics, is there a difference in surgical readmission rates between safety-net and non–safety-net hospitals?

Findings  This study of 1 252 505 patients with surgical admissions linked data from the Agency for Healthcare Research and Quality’s 2011-2014 State Inpatient Databases for 4 geographically varied states with data from the 2014 American Hospital Association annual survey; hospital risk-standardized readmission rates were calculated. After controlling for hospital characteristics and patient factors, safety-net hospitals had slightly higher readmission rates after surgery.

Meaning  Surgical patients appear to have experienced higher readmission rates at safety-net hospitals.


Importance  Medical patients discharged from safety-net hospitals (SNHs) experience higher readmission rates compared with those discharged from non-SNHs. However, little is known about whether this association persists for surgical patients.

Objectives  To examine differences in readmission rates between SNHs and non-SNHs among surgical patients after discharge and determine whether hospital characteristics might account for some of the variation.

Design, Setting, and Participants  This observational retrospective study linked the Healthcare Cost and Utilization Project State Inpatient Databases of the Agency for Healthcare Research and Quality from January 1, 2011, through December 31, 2014, for 4 states (New York, Florida, Iowa, and Washington) with data from the 2014 American Hospital Association annual survey. After identifying surgical discharges, SNHs were defined as those with the top quartile of inpatient stays paid by Medicaid or self-paid. Hospital-level risk-standardized readmission rates (RSRRs) for surgical discharges were calculated. The association between hospital RSRRs and hospital characteristics was evaluated with bivariate analyses. An estimated multivariable hierarchical linear regression model was used to examine variation in hospital RSRRs, adjusting for hospital characteristics, state, year, and SNH status. Data were analyzed from June 1, 2017, through March 1, 2018.

Exposures  Surgical care at an SNH.

Main Outcomes and Measures  Readmission after an index surgical admission.

Results  A total of 1 252 505 patients across all 4 years and states were included in the analysis (51.7% women; mean [SD] age, 52.7 [18.1] years). Bivariate analyses found that SNHs had higher mean (SD) surgical RSRRs compared with non-SNHs; significant differences were found for New York (9.6 [0.1] vs 10.9 [0.1]; P < .001) and Florida (11.6 [0.1] vs 12.1 [0.1]; P = .001). The SNHs also had higher RSRRs in these 2 states when stratified by hospital funding (nonfederal government SNHs in New York, 11.9 [0.2]; for-profit, private SNHs in Florida, 13.1 [0.2]; P < .001 for both); however, bed size was a significant factor for higher mean (SD) RSRRs only for New York (200 to 399 beds, 12.0 [0.4]; P = .006). Similar results were found for multivariable linear regression models; RSRRs were 1.02% higher for SNHs compared with non-SNHs (95% CI, 0.75%-1.29%; P < .001). Increased RSRRs were observed for hospitals in New York and Florida, teaching hospitals, and investor-owned hospitals. Factors associated with reduced RSRRs included presence of an ambulatory surgery center, cardiac catheterization capabilities, and high surgical volume.

Conclusions and Relevance  According to results of this study, surgical patients treated at SNHs experienced slightly higher RSRRs compared with those treated at non-SNHs. This association persisted after adjusting for year, state, and hospital factors, including teaching status, hospital bed size, and hospital volume.

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