The aim of this systematic review was to summarise the results of studies that compared the effects on patient outcomes for patients admitted to a supplemented primary care unit instead of a general hospital or who examined whether patients with access to a supplemented primary care unit had fewer hospital admissions than patients without such access. Patients should satisfy certain criteria, i.e. they should be in need of emergency treatment, but not need intensive treatment in hospital. A secondary aim was to summarise results of studies that compared larger supplemented primary care units with smaller ones.

We identified only three small studies as eligible for inclusion, one randomised controlled trial conducted in Norway and two observation studies conducted in England. The assessment of the evidence base shows that:

• It is possible that admission to a supplemented primary care unit compared with hospitalisation provides slightly better patient satisfaction, but the quality of the evidence for this result is low.
• There is insufficient scientific evidence to determine whether admission to a supplemented primary care unit compared to hospitalisation affects patient outcomes such as physical function and quality of life or affects the number of readmissions.
• We identified no prospective controlled studies that examined whether supplemented primary care units lead to fewer hospital admissions, or are associated with reduced expense.
• We identified no studies that compared larger intermunicipal units with smaller.