Prehospitalization factors, rather than factors linked with an index hospital stay, drove increased risk for readmission among adults aged 65 years and older, according to results from a large study in Denmark.

"Therefore, the risk for excess readmission and approaches to prevent readmission should be shared across sectors," write Mona K. Pedersen, Ph.D., of the Department of Internal Medicine and the Clinical Nursing Research Unit at Aalborg University Hospital in Denmark, and colleagues.

The researchers studied 1,267,752 admissions among 479,854 older patients who were discharged from Danish public hospitals between January 2007 and September 2010.

The researchers considered patient demographics, social determinants, clinical conditions, use of healthcare, and provider information. They excluded inpatient stays in psychiatric or private hospitals and hospices.

The index admission

They found that acute admission and recent hospital discharge prior to the index admission were the strongest predictors of readmission. Additionally, those at risk for readmission" suffered from comorbidity, consumed more drugs, and were frequent users of in- and outpatient health care services in the year prior to the index admission," the authors write.

Their findings were published online December 3 in the Journal of General Internal Medicine. In accordance with previous work, the researchers found that socioeconomic factors, such as lower income, employment status, and being male, were linked with a higher readmission risk.

"Surprisingly, we did not identify any associations between readmission and previously identified risk factors such as age, prolonged length of stay, and specific medical conditions related to the index admission," the authors write.

Denmark has universal healthcare, the authors note, so everyone has equal access to care. In countries without universal healthcare, prehospital and access factors may have a different relationship with risk for readmissions, the authors note.

Predictors of readmissions are particularly valuable because, for a significant percentage of discharges, acute readmission occurs within a month. Identifying those patients at higher risk can help inform resource allocation.

In Denmark in 2017, 18% of discharges among patients aged 67 years and older resulted in acute 30-day readmission. That rate is comparable to rates seen in large international cohort studies, according to the authors. In Western countries, reducing 30-day readmissions is a top healthcare priority.

Strengths of this study include its size, the completeness of the data, and the ability to link demographic and social data with hospital data and follow-up data, the authors write.