National Retrospective Cohort Study Assessing Association of Hospital Transfer-In Prevalence With Hospital Outcomes.

Abstract

Transferred patients are clinically complex, with high mortality risk and longer length of stay. Although interhospital transfers are common, it is unclear if hospitals with higher rates of transfer-in patients have worse risk-adjusted performance metrics because of their patient case mix. Do hospitals with higher transfer-in prevalence have worse risk-adjusted outcomes, including mortality, length of stay, and hospital charges? This study used the National Inpatient Sample from 2019 to 2020. The study included all hospitalized adults in generalizable acute care hospitals. Hierarchical regression was used to model hospitals' mean risk-adjusted mortality, length of stay, and hospital charge. Each hospital's transfer-in patient prevalence was correlated to their risk-adjusted outcomes. There were 2,811,367 encounters across 4,261 hospitals. The median age was 67 years (interquartile range, 55-78 years), 52% were female, and 68% were non-Hispanic White. The annual transfer-in prevalence for hospitals ranged from 0% to 47.4%. In the hierarchical model, transfer-in patients had higher odds of in-hospital mortality compared with nontransfer patients (OR, 1.53; 95% CI, 1.47-1.60), but hospitals with higher transfer-in patient prevalence had lower risk of mortality for transfer-in patients (OR, 0.33; 95% CI, 0.23-0.47). In the Spearman correlation, higher hospital transfer-in patient prevalence was associated with a small increase in overall risk-adjusted mortality, longer risk-adjusted mean length of stay, and greater hospital charge (ρ = 0.04, P = .006; ρ = 0.24, P < .001; and ρ = 0.10, P < .001, respectively). Our research shows that hospitals with high transfer-in prevalence have lower risk of mortality for transfer-in patients, but these hospitals have disproportionately longer lengths of stay despite rigorous risk adjustment. Future studies should investigate the feasibility of repatriation to potentially reduce the longer than expected length of stay at tertiary centers.