Frailty is a key determinant of prognosis in older adults with complex chronic conditions and in palliative care settings. The Rockwood Frailty Index (RFI), based on the accumulation of health deficits, has demonstrated prognostic value across multiple clinical contexts. This study evaluates the association between the RFI and overall survival in complex chronic and palliative patients (oncologic and non-oncologic) treated in a Hospital-at-Home (HaH) unit.

This retrospective longitudinal observational cohort study included patients aged 65 years or older admitted to a Hospital-at-Home (HaH) unit between January 1, 2021 and December 31, 2024. All patients had a recorded modified Rockwood Frailty Index (RFI) at admission and were subsequently followed through a structured case-management program led by nurse case managers via scheduled telephone follow-up.

Patients were classified into three clinical groups: complex chronic patients, non-oncologic palliative patients, and oncologic palliative patients. Non-oncologic palliative status was defined by an RFI ≥0.53, while complex chronic patients had an RFI >0.37 and <0.53. Oncologic palliative patients were classified based on referral from Oncology services regardless of frailty level.

The primary outcome was overall survival, defined as time from discharge from the HaH unit to death from any cause. Survival analyses were conducted using Kaplan-Meier curves and multivariate Cox proportional hazards regression models adjusted for relevant demographic, clinical, and laboratory covariates.

Inclusion Criteria:

• Age ≥65 years
• Admission to the Hospital-at-Home unit during the study period
• Recorded modified Rockwood Frailty Index at admission
• Participation in the post-discharge case management follow-up program

Exclusion Criteria:

• Incomplete data for frailty index calculation
• Immediate loss to follow-up after discharge

Patients aged over 65 years with a high comorbidity burden and functional dependence, and/or with advanced cancer requiring symptom management and end-of-life care.

De-identified individual participant data (IPD) underlying the results reported in publications will be shared. The shared IPD will include baseline demographic and clinical characteristics, outcome measures, and relevant covariates. Data will be made available upon reasonable request after publication of the study results, subject to institutional approval and in accordance with applicable data protection and privacy regulations.

Starting after publication of the study results; duration of availability will be determined according to institutional policies.

Qualified researchers who submit a reasonable research proposal will be able to access the de-identified individual participant data (IPD) and supporting documentation (such as the data dictionary). Access will be granted after review and approval by the study investigators and the corresponding institution. Data will be provided in a de-identified format and shared through secure data transfer methods. Researchers may be required to sign a data use agreement to ensure compliance with ethical standards, data protection regulations, and intended use of the data.