Assess the change in levels of neuro-metabolites measured by MRS from week 0 (before switching to the efavirenz-based therapy) and then at week 8 (after completing 9 weeks of integrase-inhibitor based regimen with Stribild). Two areas of the brain: 1) posterior cingulate gyrus and 2) anterior cingulate will be assessed for the levels of brain Cr, GABA and GLU.

The arbitrary units are expressed as the output from MRS software. While similar to concentration (mM) due to assumptions in the software, it is best expressed as arbitrary units for comparison from week 0 to week 8.

Assess changes in neural activation correlated with affective disturbances associated with efavirenz-based therapy using fMRI employing an Emotional Word/Go-NoGo task paradigm that probes affective symptomatologies typical with EFV use, specifically anxiety/dysphoria and affective dysregulation and their association with changes in cognitive function. Four brain regions of interests (ROIs) are specified to show the differential frontal-limbic activation patterns in the task-evoked neural responses to the 3 linear contrasts of Pre-switch / Post-switch / Pre- vs. Post-switch: [Negative Word vs. Neutral Word] x [No-Go Trial Block vs. Go Trial Block]: anterior Frontal Pole (aFP), posterior Cingulate Gyrus (pCG), dorsal anterior Cingulate Gyrus (daCG), Left Hippocampus (LHC). A linear mixed-effects model is utilized to examine the effect sizes of the key Regimen/Condition contrasts, with the Subject factor as the random-effect and Age incorporated as a co-variate of no interest.

8 of 10 enrolled patients passed QA testing to be included in the final analyses. The 3 linear contrasts of Pre-switch/Post-switch/Pre- vs. Post-switch: [Neg vs.Neu] x [No-Go vs. Go] are reported as z-score (standardized effect size measures with SD=1). Z-score is obtained for each subject, group Z-score is obtained via a mixed-effects model.

Use MRS to evaluate a fuller panel of known neurometabolites (in addition to the primary endpoints) between week 0 and week 8 to identify prominent and significant changes associated with EFV use.

The arbitrary units are expressed as the output from MRS software. While similar to concentration (mM) due to assumptions in the software, it is best expressed as arbitrary units for comparison from week 0 to week 8.

Assess for changes in cognitive and affective function prior to and after switching off EFV-based regimen. Indexes used to access neurocognitive changes included:

1. Wechsler Adult Intelligence Scale (WAIS-R) Digital Symbol Substitution Test: sensitive to brain damage, dementia, age and depressive changes. Range of 0-100, the higher the score the better the person's performance
2. Hamilton Rating Scale for Depression (HAMD): Measure of depression. Score of 0-7 is normal, score of >20 is moderate/severe depression
3. Depression Anxiety Stress Scale (DASS-21) the lower the score, the less severe depression, anxiety and stress. Scale range of 0-63
4. Frontal Systems Behavior Scale (FRSBE): Increased score indicates greater behavioral impairment associated with frontal systems, range 37.2 to 186

6. Spielberger state trait anxiety inventory (STAI): the higher the score the greater then anxiety level, range of 20 to 80.

Several Indexes were used to access neurocognitive changes: WAIS, HAMD, FRSBE, DASS-21, STAI.

Participants were given these tests prior to and after drug switch.

Measure the change in fasting lipid panel prior to and after switching off EFV-based regimen.

Change in fasting lipid profile was measured: total cholesterol, HDL and LDL levels.

Assess for changes in sleep pattern and quality prior to and after switching off EFV-based regimen through a self-administered Pittsburg Sleep Quality Index (PSQI). Measure consists of 19 items with each weighted on 0-3 scale and the sum produces a total score, which ranges from 0-21. The lower the score the healthier the sleep quality; minimum Score = 0 (better); maximum Score = 21 (worse).

Evaluate patient preference in ART regimen (Atripla, EFV/FTC/TDF versus EVG/COBI/FTC/TDF) through a self-administered questionnaire.

Patients were surveyed at the end of the study with a single question regarding their ART preference. They are asked to pick one of the 3 answers: 1. prefer Atripla, 2. prefer the new drug (Stribild) or 3. no preference. The number of patients who would like to switch to study drug, Stribild, are indicated by the percentage.

Change in markers of immune activation and inflammation associated with change to Stibild: sCD14, IP-10,sCD163, IL-6)

Inflammatory markers were measured pre- and post-drug switch from Atripla to Stibild.

Level of EFV (efavirenz) in Atripla and its two known metabolites known to cause cerebral side effects, 7-hydroxy (OH) EFV and 8-OH EFV, were measured in the plasma prior to switch off Atripla and after 8 weeks of RAL-based regimen (no EFV).