Since 2001, the region of Lombardy has accreditated nursing homes named R.S.A. "Residenza Sanitario-Assistenziale", which make up Italy's principal RSA network with the annual turnover of approximately 60,000 people. The most noteworthy element of the reform introduced is a concentration on resident's frailty rather than disability. This is assessed by using SOSIA, a form for intermediate observation of assistance. Residents are classified into eight classes of frailty, called isofrailty classes of SOSIA, which are differentiated by how compromised their motor and cognitive skills are, and by the presence of comorbidity. The study presents the methodology used to identify and estimate cut-offs of three indicators employed in SOSIA classification. It also discusses their characteristics versus other evaluation systems, such as Resource Utilization Group RUG-III and Autonomie Gerontologique--Groupes Iso-Resources AGGIR.