BackgroundSectorization of health care systems causes inefficient treatment, especially for elderly people with cognitive impairments. The transition from hospital care to primary care is insufficiently coordinated, and communication between health care providers is often lacking. Consequences include a further deterioration of health, higher rates of hospital readmission, and institutionalization. Models of collaborative care have shown their efficacy in primary care by improving patient-related outcomes. The main goal of this trial is to test the effectiveness of a collaborative care model for people with cognitive impairment (PCI) and current hospital treatment due to a somatic illness to improve the continuity of treatment and care across the transition between the in-hospital and adjoining primary care sectors.Methods The trial is a longitudinal multisite randomized controlled trial with two arms (“care as usual” and “intersectoral care management”). Inclusion criteria at the time of hospital admission due to a somatic illness: age 70+, cognitive impairment (Mini Mental State Examination, MMSE ≤ 26), live at home, provide written informed consent. Each participant will have a baseline assessment at the hospital and two follow-up assessments at home (three and twelve months after discharge). The estimated sample size is n=398 participants together with (where available) their respective informal caregivers.In the intersectoral care management group, specialized care managers will develop, implement and monitor individualized treatment and care based on comprehensive assessments of the patients and informal caregivers for unmet needs at the hospital and in their homes. Primary outcomes are (1) activities of daily living, (2) readmission to the hospital, and (3) institutionalization. Secondary outcomes include (a) frailty, (b) delirium, (c) quality of life, (d) cognitive status, (e) behavioral and psychological symptoms of dementia, (f) utilization of services, and (g) informal caregiver burden.DiscussionIn the event of proving efficacy, this trial delivers proof of concept for implementation into routine care. Cost-effectiveness analyses as well as an independent process evaluation increase the likelihood of meeting this goal. The trial allows in-depth analysis of mediating and moderating effects for different health outcomes at the interface between hospital care and primary care. Highlighting treatment and care, the study will provide insights into unmet needs at the time of hospital admission, the opportunities and barriers to meeting those needs during the hospital stay and after discharge.Trial registration ClinicalTrials.gov Identifier: NCT03359408