The purpose of this study is to assess adherence, tolerability and satisfaction of each eligible HIV subjects switching from a two- or three-pill tenofovir-emtricitabine-efavirenz (TDF-FTC-EFV) to a one-pill TDF-FTC-EFV treatment.

Each eligible patient will be screened from de SHCS database. Each refusal and drop-out will be documented. A pre-visit (V-1) will be scheduled for informed consent, V0 for inclusion (V-1 and V0 may occur on the same day), V1 one month post-inclusion and V2 4 to 7 months post-inclusion. V0, V1 and V2 will be planned during regular medical visits.

Eligible patients either get their cART in their usual pharmacy according to standard of care, or take part in a routine adherence-enhancing program(adherence subgroup)run by the pharmacists of the outpatient medical clinic.

In the adherence subgroup, adherence is assessed electronically by MEMS (Medication event monitoring system) monitors on a regular basis.

Inclusion Criteria:

• patients under TDF-FTC-EFV
• followed up at the Service of Infectious Disease of the University Hospital of Lausanne
• enrolled in the SHCS

Exclusion Criteria:

• patients receiving TDF-FTC-EFV in combination with other ARTs
• patients under TDF-FTC-EFV for less than 3 months
• patients not fluent in French

Patients under TDF-FTC-EFV followed up at the Service of Infectious Disease of the University Hospital of Lausanne and enrolled in the Swiss HIV Cohort Study (SHCS) Adherence subgroup: patients enrolled in the HIV adherence program at the pharmacy of the Department of Ambulatory Care & Community Medicine in Lausanne.