Cost-of-illness studies in palliative care (PC) are a growing area of interest in health economics activity. They are, in part, stakeholders' basis for deciding the allocation of the scarce public and private economic resources. There is no standard methodology to capture the formal and informal costs and expenses that health services and patients and their caregivers make during the PC attention period due to non-standard health services, and data capture approaches.

Methods / Analysis Prospective study on the burden of disease of PC on the outpatient/domiciliary attention. Proposed in three phases: Phase I: Systematic Review of Literature to identify de types of costs and proposed methodologies to identify and determine de economic burden of PC. With collected data, create a questionnaire to register the costs of services covered by the healthcare system and those covered by patients/caregivers (PROSPERO CRD42021250086). Phase II: Questionnaire piloting. Phase III: Transversal study of costs, collecting data from public healthcare billing and patient/caregivers payments to cover PC on selected patients. Final methodologic proposal to study billing/costs of outpatient/domiciliary PC.

Inclusion criteria:

• Clinical diagnosis of breast, lung, and colorectal neoplasm or Chronic Heart Failure (CHF) or Chronic Obstructive Pulmonary Disease (COPD).
• Patient and caregivers must be able to maintain a 1-hour telephonic interview.
• Patient and caregivers must allow one (1) more telephone call to revise data.

Exclusion Criteria:

• Cases with an open legal process.
• Family/caregivers of patients that can't communicate in fluent Spanish or Catalan.

Patients with a history of breast, lung, and colorectal neoplasm or Chronic Heart Failure (CHF) or Chronic Obstructive Pulmonary Disease (COPD), managed in the outpatient/domiciliary scenarios and their families/caregivers.

In case the obtained database gives data of public interest, can be used to make parallel analyses, supervised/directed by one of the headline authors.