Prevalence, characteristics and risk factors of frequently readmitted patients to an internal medicine service.

Background: Unplanned hospital readmissions (HRA), which have been used as key performance index of healthcare quality, are becoming more prevalent. They are associated with substantial financial burden to hospital systems and considerable impacts on patients' physical and mental health. Patients with frequent readmissions are not well studied.

Aims: To determine the prevalence, characteristics and risk factors associated with frequent readmissions (FRA) to an internal medicine service at a tertiary public hospital.

Method: A retrospective observational study was conducted at an internal medicine service in a tertiary teaching hospital between 1 January 2010 and 30 June 2016. FRA was defined as four or more readmissions within 12 months of discharge from the index admission (IA). Demographic and clinical characteristics and potential risk factors were evaluated.

Results: A total of 50 515 patients was included; 1657 (3.3%) had FRA and were associated with nearly 2.5 times higher in 12-month mortality rates. They were older, had higher rates of indigenous Australians (3.2%), more disadvantaged status (index of relative socio-economic disadvantage decile of 5.3) and more comorbidities (mean Charlson comorbidity index 1.4) in comparison, to infrequent readmission group. The mean length of hospital stay during the IA was 6 days for FRA group (21.4% staying more than 7 days) with higher incidence of discharge against medical advice (2.0% higher). Intensive care unit admission rate was 6.6% for FRA group compared with 3.9% for infrequent readmission group. Multivariate analysis showed mental disease and disorders, neoplastic, alcohol/drug use and alcohol/drug-induced organic mental disorders are associated with FRA.

Conclusion: The risk factors associated with FRA were older age, indigenous status, being socially disadvantaged, having higher comorbidities and discharging against medical advice. Conditions that lead to FRA were mental disorders, alcohol/drug use and alcohol/drug-induced organic mental disorders and neoplastic disorders.