The PRESTIGIO Registry is an Observational, prospective, multicentre study that includes patients, regularly followed by Italian Infectious Disease Centres, with HIV-1 infection and documented resistance to the 4 classes of antiretroviral drugs: nucleoside reverse transcriptase inhibitors (NRTI), non-nucleoside reverse transcriptase inhibitors (NNRTI), protease inhibitors (PI), and integrase inhibitors (INSTI).

Main objective of this register is to evaluate in the study population:

• the long-term effectiveness of different antiretroviral regimes;
• evolution of the genotype and phenotypic susceptibility of antiretroviral drugs used in patients with virological failure;
• mortality;
• incidence of opportunistic AIDS-related infections and chronic conditions (comorbidity);
• determinants of clinical outcomes including virological/immunological/inflammatory markers.
• antiretroviral therapy (ART) compliance and health assessments;
• drug-economy indications related to the clinical management of this complex sub-population.

The PRESTIGIO Register consists of a systematic and continuous collection of data on clinical, laboratory and treatment characteristics of patients with documented resistance to the 4 classes of antiretroviral drugs that meet the defined inclusion and exclusion criteria.

All the clinical centres of Infectious Diseases of the different Italian regions can participate in the implementation of the Registry. Based on an analysis conducted on data collected in an AIFA register, established for the purpose of monitoring the use of dolutegravir (DTG) 50 mg Bis in Die (BID) and containing about 200 patients with the criteria specified in this protocol, the size currently conceivable for this register in Italy is about 300 patients.

The collection of clinical information and biological samples will begin once the Ethics Committee of the participating centers has approved the participation in the registry and will continue for at least three years.

Inclusion Criteria:

• subjects with HIV-1 infection;
• age >14 years;
• documented resistance to the 4 classes of antiretroviral drugs (NRTI, NNRTI, PI, INI), defined as resistance (at least intermediate) to at least one of the drugs in each class according to the Stanford algorithm. Resistance can be documented either at the time of inclusion in the study or previously documented throughout the patient's therapeutic history.

Exclusion Criteria:

• none

The Italian PRESTIGIO register will include patients who are regularly monitored according to the principles of good clinical practice in the Italian Infectious Diseases Centres of all Italian regions.

Patients will be included in the registry once informed consent has been obtained (Annex 2) signed to allow for the recording and analysis of clinical/laboratory data and for the collection of biological samples, subject to the guarantee of anonymity and independence of therapeutic choices and clinical management, which will be the sole responsibility of the treating physician. The consent collected must be entered in the Register.

IPD will be shared in scientific conferences and meetings.

Data will become available after 1 year from the first visit first patient (FVFP) and they will be available until patients registry will be updated.

Must to be a partecipant of the registry.