Inclusion Criteria:  HIV-1 infected patients aged > 50 years old naive patients receiving doravirine-based regimens both as single drug and as in fixed combination with lamivudine and tenofovir disoproxil fumarate experienced patients with persistently undetectable plasma HIV viral load (HIV RNA < 50 copies/mL) for at least 6 months, who switched from any antiretroviral drug to doravirine-based regimens, both as single drug and as fixed combination with lamivudine and tenofovir disoproxil fumarate, because of toxicity, convenience or other reasons. estimated creatinine clearance (CrCl) ≥50mL/min.  Exclusion Criteria:  previous genotypic testing showing resistance mutations to doravirine acute hepatitis, decompensated liver disease, liver cirrhosis use of systemic immunosuppressive therapy