All-cause unplanned readmissions in the United States: insights from the Nationwide Readmission Database.

Background: There are few studies looking into adult, all-cause and age-group-specific unplanned readmissions. The predictors of such unplanned readmissions for all inpatient encounters remain obscure.

Aims: To describe the incidence and factors associated with unplanned readmissions in all inpatient encounters in the United States.

Methods: The US Nationwide Readmission Database (NRD) is a representative sample of hospitalisations in the United States (from approximately 28 states) accounting for approximately 60% of the US population. All inpatient encounters during January-November 2017 in the NRD were evaluated for the rates, predictors and costs of unplanned 30 days readmissions for age groups 18-44 years, 45-64 years, 65-75 years and ≥75 years. Elective readmissions and those patients who died on their index hospitalisations were excluded. Weighted analysis was performed to obtain nationally representative data.

Results: We identified 28 942 224 inpatient encounters with a total of 3 051 189 (10.5%) unplanned readmissions within 30 days. The age groups 18-44 years, 45-64 years, 65-74 years and ≥75 years had 7.0%, 12.0%, 11.7% and 12.3% readmissions respectively. Female gender, private insurance and elective admissions were negative predictors for readmissions. For the group aged 18-44 years, schizophrenia and diabetes mellitus complications were the most frequent primary diagnosis for readmissions, while in all older age groups septicaemia and heart failure were the most frequent primary diagnosis for readmissions.

Conclusions: Thirty-day unplanned readmissions are common in patients over age 45 years, leading to significant morbidity. Effective strategies for reducing unplanned readmission may help to improve quality of care, outcomes and higher value care.