Italian Prospective Data Collection for Better Patient Characterization in a Highly Treatment Experienced Population

Data collection for better patient characterization in a highly treatment experienced population. Studying the clinical practice for the treatment of HIV multiexperienced patients in the real life. The research will be divided into two phases: * The first phase intends to define and understand the clinical practice using a questionnaire about general topics: definitions of multiexperienced patients and VL failure, therapeutic strategies and behaviour in particular cases. * The second part of the research will collect the clinical data of double PIs failure patients.