Introduction : Several studies show that a high percentage of people admitted to acute care hospitals could be treated in alternative care facilities of less intensity. The hospitalisation of fragile elderly people or people with chronic illnesses can give rise to various complications, as well as represent a high cost in terms of healthcare. In recent years, as an alternative to conventional hospitalisation, a number of new specific units have been set up in intermediate care hospitals in Catalonia: sub-acute care units. Their goal is to guarantee the care continuum with a geriatric rehabilitation approach from the outset, for those multi-pathological elderly patients with decompensation, who call for treatment and control of their pathologies. Sub-acute care becomes an alternative to conventional hospitalisation, with the contribution of interdisciplinary treatment plans to the complex needs of patients with chronic illnesses. They are people that call for patient-centred care, over and above managing the illness. In this setting, the rehabilitation therapies they need can be applied, with an integrated care focus and at a lower cost, in order to achieve improved health outcomes, more rapid functional improvement and with a care continuum process that is better adapted to their needs. Objective : To appraise the improvement in care for people with complex chronic illnesses, in the context of comprehensive and integrated care, through on-going care and an adaptation of resources tailored to patient needs, through the implementation of sub-acute care units in the realm of intermediate care. A sample of 591 cases admitted to eleven sub-acute care units across Catalonia were collected in a defined period of time, from February to March 2015. The care process and its outcomes, as well as their adjustment to the standards established for this resource, were analysed. Methodology : A statistical analysis of the sample endeavours to classify it into different areas that allow us to identify the socio-demographic and epidemiological profile of treated patients, as well as characteristics of the care process and its results. An emphasis has been placed on the analysis of readmissions, the level of dependence upon admission and release (Barthel) and mortality during admission and at six months of care, among other elements. Results : The analysis of the sample has identified that the average age of treated patients is 86 years of age, 63% of whom are women. Thirty-seven per cent of treated patients are complex chronic patients, and 17% are patients with advanced chronic illness. Eighty-two per cent of patients originate from emergency services, 8% from primary healthcare and 6% from nursing homes. The average length of stay is ten days. The most prevalent diagnosis, 55% of cases, involves respiratory illnesses, and 20% account for circulatory system illnesses. The number of readmissions a month after release stands at approximately 20%. The rate of mortality upon release is 18%, and 30% after six months. Conclusions : Sub-acute care units are an alternative to conventional hospitalisation that offer a specific and agile care system for geriatric patients with decompensation treated in emergency services or detected in primary care. Care becomes personalised, treating their many pathologies and their personal and context-based determining factors, which do not require cutting-edge diagnosis or therapy, but rather a stay in a facility with an interdisciplinary, person-centred approach, and where the possibility for functional recovery appropriate for the geriatric patient is offered, which allows them to return to their usual environment in the same or similar functional conditions they had previous to the acute decompensation of their chronic disease.