Same-Hospital Re-Admission Rate Is Not Reliable for Measuring Post-Operative Infection-Related Re-Admission

Background: Post-operative infections cause morbidity, consume resources, and are an important quality measure in assessing and comparing hospitals. Commonly used metrics do not account for re-admission to a different hospital. The Nationwide Readmissions Database (NRD) tracks re-admissions across United States (US) hospitals. Infection-related re-admission across US hospitals has not been studied previously.

Patients and methods: The 2013 NRD was queried for admissions with a primary International Classification of Diseases and Related Health Problems, 9th revision, Clinical Modification code for the most frequently performed operations. Non-elective all-cause, infection-related, and different hospital 30-day re-admission rates were calculated, using All Patient Refined Diagnosis Related Groups codes. Multi-variable logistic regression identified risk factors for re-admission.

Results: Of 826,836 surviving to discharge, 39,281 (4.8%) had an unplanned re-admission within 30 days, occurring at a different hospital 20.5% of the time. The most common reason for re-admission was infection (25.1%). Orthopedic and spinal procedures were at highest risk for all-cause and infection-related different hospital re-admission. Infection-related different hospital re-admission risk factors included: Length of stay >30 days (odds ratio [OR] 2.28 [1.62-3.21], p < 0.01), age ≥65 years (OR 1.56 [1.38-1.76], p < 0.01), and Charlson Comorbidity Index >1 (OR 1.14 [1.01-1.28], p < 0.01) and differed from predictors of same-hospital infectious re-admission. Non-elective surgical procedure (OR 0.79 [0.72-0.87], p < 0.01) and initial hospitalization at a large hospital (OR 0.66 [0.59-0.74], p < 0.01) were protective.

Conclusion: A substantial proportion of post-operative re-admissions are missed by same-hospital re-admission data. All-cause and infection-related post-operative re-admissions to a different hospital are affected by unique patient and institution-specific factors. Re-admission reduction programs, quality metrics, and policy based on same hospital re-admission data should be updated to incorporate different hospital re-admission.