Patients leaving without being seen from the emergency department: A prediction model using machine learning on a nationwide database

OBJECTIVE: The objective of this study was to develop a US‐representative prediction model identifying factors with a greater likelihood of patients leaving without being seen. METHODS: We conducted a retrospective cohort analysis using a 2016 nationwide emergency department (ED) sample. Patient factors considered for analysis were the following: age, sex, acuity, chronic diseases, weekend visit, quarter of presentation, median household income quartile for patient's zip code, primary/secondary insurance, total charges for the visit, and urban/rural household. Hospital factors considered were urban/rural location, trauma center/teaching hospital, and annual ED volume. Multivariable logistic regression was used to find significant predictors and their interactions. A random forest algorithm was used to determine the order of importance of factors. RESULTS: A total of 32,680,232 hospital‐based ED visits with 466,047 incidences of leaving without being seen were included. The cohort comprised 55.5% females, with a median (IQR) age of 37 (21–58) years. Positively associating factors were male sex (odds ratio [OR], 1.22; 99% confidence interval [CI], 1.17–1.26), lower acuity (P < 0.001), and annual ED visits ≥60,000 (OR, 1.44; 99% CI, 1.21–1.7) versus <20,000. Negatively associating factors were primary insurance being Medicare/Tricare or private insurance (P < 0.001); weekend presentations (OR, 0.87; 99% CI, 0.85–0.89); age >64 or <18 years (P < 0.001); and higher median household income for patient's zip code second (OR, 0.86; 99% CI, 0.77–0.97), third (OR, 0.8; 99% CI, 0.7–0.91), and fourth (OR, 0.7; 99% CI, 0.6–0.8) quartiles versus the first quartile. Significant interactions existed between age, acuity, primary insurance, and chronic conditions. Primary insurance was the most predictive. CONCLUSION: Our derivation model reiterated several modifiable and non‐modifiable risk factors for leaving without being seen established previously while rejecting the importance of others.