Running Title: The Patient's Pain Seems to be a Reliable Risk Factor for Decompensation Among Multimorbid Patients in Residential Care.

The concept of multimorbidity was first published in 1976. Multimorbidity has been defined by the World Health Organization (WHO) as people being affected by two or more chronic health conditions. Multimorbidity is a very interesting and challenging concept particularly for Family Medicine (FM), given the increasing prevalence of chronic illness in an aging population across all developed countries. It is closely related to a global or comprehensive view of the patient, which is a core competency of FM, as defined, for instance, by the World Organization of National Colleges, Academies and Academic Associations of General Practitioners/Family Physicians (WONCA). It is a global 'functional' view (useful for Long-Term Care) versus a 'disease' centered point of view (useful for acute care).

The European General Practice Research Network (EGPRN) has created a research agenda specifically designed for methodological and instrumental research, which includes the development of primary care epidemiology, focusing on patient-centered health. A comprehensive definition of the concept of multimorbidity (i.e. one which is both understandable and usable for further collaborative research) was an important objective for this research network. The objective was to help researchers in FM to investigate the complexity of patients' conditions and their overall impact on patients' health. This concept of multimorbidity could be an additional tool for Family Physicians (FPs), enabling them to prevent decompensation.

A research team, including 9 national groups, all active within the EGPRN, has created a research community for the purpose of clarifying the concept of multimorbidity for FM throughout Europe. This group produced a comprehensive definition of the concept of multimorbidity through a systematic review of literature. This concept was translated into most European languages for use in further collaborative research. Finally, it was validated using qualitative research throughout Europe and a specific research agenda was issued. The EGPRN concept of multimorbidity included a set of different variables assessing patients' multimorbidity, multimorbidity modulating factors and multimorbidity consequences.

Decompensation (i.e. death or hospitalization in acute care) is a challenge for FM as FPs, being familiar with their patient's health status, could miss tiny factors which, if noticed, could help to prevent decompensation. A predictive model that could be integrated into their clinical practice could help them to prevent decompensation and avoid serious health outcomes for their patients. The EGPRN concept of multimorbidity was considered highly suitable for a purpose such as this. It could lead to a usable model for preventing decompensation.

The French population is aging, with one in three people over 60 years of age in 2050. Consequently, the number of dependent patients, some requiring institutionalization in Care homes (CHs), is growing. Patients residing in CHs are included in the EGPRN definition of multimorbidity. In France, as in most European countries, patients in residential care are treated by FPs.