Frequent use of hospital inpatient services during a nine year period: a retrospective cohort study

Frequent use (FU) of hospital services impacts on patients and health service expenditure. Studies examining FU in emergency departments and inpatient settings have found heterogeneity and the need to differentiate between potentially preventable FU and that associated with ongoing management of complex conditions. Psychosocial factors have often been reported as underpinning or exacerbating the phenomena. Most FU studies have been limited by time, to a single study site, or restricted to specific diagnoses or patient groups. This study provides a comprehensive description of adult patient characteristics, conditions and risk factors associated with FU, based on admissions to the five public hospitals in the Northern Territory (NT) of Australia over a nine year period. The study population is distinctive comprising both Aboriginal and non-Aboriginal patients. Data on all inpatient episodes in NT public hospitals between 2005 and 2013 was analysed to identify patients with any FU (four or more episodes within any 12-month period) and measure FU duration (number of FU years) and intensity (mean number of episodes per FU year). Pregnancy, alcohol-related and mental health condition flags were assigned to patients with any episode with relevant diagnoses during the study period. Multivariate analysis was used to assess factors associated with any FU, FU duration and FU intensity, separately for Aboriginal and non-Aboriginal patients. Of people with any inpatient episodes during the study period, 13.6% were frequent users (Aboriginal 22%, non-Aboriginal 10%) accounting for 46.6% of all episodes. 73% of frequent users had only one FU year. Any FU and increased FU duration were more common among individuals who were: Aboriginal; older; female; and those with a pregnancy, alcohol or mental health flag. Having two or more alcohol-related episodes in the nine-year period was strongly associated with any FU for both Aboriginal (odds ratio 8.9, 95% CI. 8.20-9.66) and non-Aboriginal patients (11.5, 9.92-13.26). For many people, frequent inpatient treatment is necessary and unavoidable. This study suggests that damage arising from excessive alcohol consumption (either personal or by others) is the single most avoidable factor associated with FU, particularly for Aboriginal people.