Association Between Interhospital Transfer, Readmission, and Inpatient Mortality Among Older Adults

Interhospital transfer (IHT) is a key strategy for providing access to specialty care; however, it is associated with multiple adverse outcomes, including prolonged length of stay, increased risk of inpatient mortality, and reduced rates of discharge home, particularly among older adults. We hypothesized that older patients who experience IHT would have a higher rate of acute-care hospital readmissions compared to older adults who do not experience IHT.

We used the Healthcare Cost and Utilization Project's 2019 National Readmissions Database to identify adults 65+ who had and had not undergone IHT. We used unadjusted and adjusted logistic regression stratified by region, clustered by hospital and weighted by individual to measure the association between IHT and the odds of readmission and in-hospital mortality.

Of the 11,836,556 older adults included in the weighted analysis, 0.9% experienced IHT. After adjusting for confounders including mortality risk, risk of readmission, admitting service, insurer, procedure characteristics, and others, IHT was associated with increased readmission rates (AOR 1.09, 95% CI: 1.01-1.18) and with increased risk of in-hospital mortality (AOR 1.91, 95% CI: 1.81-2.02). In a sensitivity analysis, odds of readmission within 30 days were 29% higher for older adults who had undergone IHT compared to those who had not (AOR 1.29, 95% CI: 1.19-1.40). All comparisons are p < 0.001.

IHT is associated with increased readmission and mortality risk among older adults. These findings add to a burgeoning evidence base suggesting that IHT is associated with many long-term risks to older adults. Further research is needed to characterize the underlying drivers of these findings and to develop evidence-based practices to improve IHT processes for older adults.