An assessment of the Portuguese health system estimates the overall burden of chronic diseases in the Portuguese population (regardless of age/gender) is follows: (i) 18% of Portuguese users of the National Health System have one chronic disease, (ii) 11% of users have two chronic diseases, (iii) 8% of users have three chronic diseases, and (iv) 22% of users have four or more chronic diseases; therefore, at least 59% of the Portuguese population has one or more chronic diseases (estimate). Moreover, the same report reveals that multimorbidity increases with age, with a maximum between 80 and 90 years old. Moreover, according to the research published in 2019 concerning the first National Health Examination Survey, the authors reported a high prevalence of multimorbidity among individuals aged 65 and older, estimated at 78.3% for the Portuguese population sample used in their research (estimates reported by age groups of 65-69, 70-74, 75-79 and 80 years and older: 72.8%, 78.2%, 81.9%, and 83.4%, respectively). Studying individual aging by integrating a continuous and accessible care model that allows elderly individuals as well as family caregivers to monitor and manage their health at home- always under the supervision of health professionals, which may enable the management of various chronic conditions (multimorbidity) and provide a "safety net" before a health crisis requiring emergency department care occurs. To promote improved health-related quality of life among elderly individuals by requalifying their potential and allowing them to live more autonomously, the following tasks are essential to identify the appropriate self-care behavior that allows determining, planning, and assessing preventive nursing care needs. Health care for patients with multimorbidity and applicable intervention strategies yield better outcomes when structured based on a previous evaluation of the patient's self-care deficits.

Most aging populations report chronic illnesses, which are usually permanent or recurrent, significantly affect well-being and quality of life, require daily and consistent healthcare management and last more than three months. With chronic illness now the significant health threat and the primary driver of healthcare costs, researchers, healthcare providers, and payers are focusing on interventions that can prevent or control exacerbations. In this context, the importance of self-care is increasingly recognized.

Self-care is essential in aging, mainly when changes occur in the person's health condition. Theoretically, this process involves three linked sequential behaviors captured in the critical concepts of self-care maintenance, self-care monitoring, and self-care management. Self-care maintenance addresses behaviors used by patients with a chronic illness to maintain physical and emotional stability (e.g., medication adherence), while self-care monitoring involves the behavior of observing oneself for signs and symptoms(e.g., checking blood pressure). Self-care monitoring is the link or bridge between self-care maintenance and self-care management. A core goal of self-care monitoring is symptom recognition; once recognized, self-care management (e.g., taking medicine for a symptom) can occur, with behaviors that reflect a response to the observed symptoms. There are two approaches to measurement: generic and disease-specific. Generic measures apply to a wide variety of patients. Disease-specific measures are helpful in specific groups with a single condition. Disease-specific measures are more responsive because they target issues experienced by patients with an explicit condition. Generic measures allow comparison among patients with different conditions and accommodate those with more than one diagnosis. The instrument studied within this project's scope, the "Self-Care of Chronic Illness Inventory - Patient Version" (version 4), is a generic measure designed to assess the process of self-care used by individuals with various chronic conditions.