Clinical Complexity in Internal Medicine Wards. San MAtteo Complexity Study

The progressive rising of multimorbidity, which has been always considered the hallmark of clinical complexity (CC), has made management of the "complex" patient one of the most topical and challenging issues in medicine. However, patient-related factors (multimorbidity, age, frailty, disease severity) pertain only to the biological complexity, while CC is the result of the dynamic interaction between biological complexity and a number of other coexisting factors (socio-economic, cultural, behavioural, environmental). Starting from these premises, the investigators designed a five-year observational prospective longitudinal study that aims to validate and compare a CC score system on a large cohort of patients (n=1000) admitted in internal medicine wards. Clinicians, biostatisticians and epidemiologists will cooperate into the project. A questionnaire that encompasses the main biological and extra-biological factors was designed (Clinical Complexity Index, CCI) by a multiprofessional consensus. This questionnaire will be administered by the investigators to the patients and validated. Consecutive patients will be enrolled every other week for two years and followed-up for 5 years. The primary endpoint will be the validation of the CCI. Thereafter, the investigators will evaluate the correlation between the CCI and the length of stay of the index hospitalization, assuming that a higher CCI score is associated with longer length of stay. The secondary endpoints will be the demonstration of the association between higher CCI score and more health resources utilization (i.e., evaluating occurrence of hospital readmissions, number of accesses to the emergency room, visits at the outpatient clinic, different drugs prescribed and hospital reimbursement according to the local diagnosis-related group \[DRG\] system) along with worse prognosis (mortality at 1 and 5 years).