Short-term Increase in Risk of Overweight and Concomitant Systolic Blood Pressure Elevation in Treatment-Naïve Persons Starting INSTI-Based Antiretroviral Therapy.

OBJECTIVE: Integrase strand transfer inhibitors (INSTI) have been associated with weight gain, but their effect on short-term overweight and obesity incidence, blood pressure (BP), and metabolic markers has not been described in treatment-naïve people with HIV(PWH). METHOD: Medical records of treatment-naïve persons starting antiretroviral therapy (ART) at the HIV Clinic of University Hospital of Elche, Spain, between January 2007 and July 2019 were reviewed retrospectively. Standard procedures included measurements of weight, BP, and metabolic assessment. Data at baseline, 48, 72, and 96 weeks post ART initiation were analyzed. We used Cox mixed-effects model to generate predictions of body mass index (BMI) over time and generalized additive mixed models to relax the linearity assumptions and generate 95% confidence intervals in the multivariable adjustment. RESULTS: Among 219 (median age, 44.0 years; interquartile range [IQR], 37.0-53.5; 46 females) participants. Baseline weight mean (standard deviation) was 70.4 (13.7) kg without difference between regimens; 66% had a BMI <25 kg/mt2. The incidence of overweight and obesity was significantly greater in persons starting INSTI-based regimens: 15 (36.6%) of 41 patients treated with INSTI versus 30 (28.9%) of 104 treated with other ART regimens (hazard ratio, 2.3; 95% CI, 1.2-4.4; P = .011). In contrast to other ART regimens, patients treated with INSTI showed a significant increase in systolic BP (SBP) (adjusted increase, 7.0 mmHg; 95% CI, 0.3-13.7; P = .039) that was correlated with weight gain (r = 0.13; 95% CI, 0.10-0.16; P < .001). Patients who reached overweight and obesity in INSTI-based ART showed a significant increase in LDL cholesterol. CONCLUSIONS: Integrase strand transfer inhibitors-based ART was associated in the short-term with a greater risk of overweight and obesity and SBP elevation. Patients developing overweight and obesity increased low-density lipoprotein cholesterol with no other metabolic disturbances.

High-grade anal intraepithelial neoplasia is associated with HIV-1 RNA rectal shedding in virologically suppressed MSM.

OBJECTIVE: The protective effect of ART has not yet been definitively established in MSM. We aimed to characterize the factors associated with persistent HIV-1 RNA rectal shedding. METHODS: Prospective study including virologically suppressed MSM from an HIV cohort. High-resolution anoscopy (HRA) was performed for screening of anal dysplasia, and rectal sampling for HIV-1 RNA quantification and sexually transmitted infections (STIs) investigation through multiplex PCR. Both generalized linear mixed (GLM) and zero-altered negative binomial (ZANB) models were performed. RESULTS: One hundred and fifty-five rectal swab samples from 132 virologically suppressed MSM were included. HIV-1 RNA was detectable in 61 (39.3%) samples, with median (IQR) rectal viral load (rVL) of 295.8 (158.8-522) copies/swab. Multivariable GLM showed that the presence of high-grade anal intraepithelial neoplasia (HG-AIN; OR 2.85 [95% CI 1.10-7.38]) and a protease inhibitor-based regimen (OR 2.49 [0.98-6.34]) resulted in increased risk for rectal HIV-1 shedding, whereas higher nadir CD4+/CD8+ T-cell ratio (OR 0.18 [0.04-0.93]) was negatively associated with rectal shedding. ZANB analyses showed that the best predictors of having detectable rVL were lower nadir CD4+/CD8+ T-cell ratio (OR 0.98 [0.96-0.99]) and PI-based regimens (OR 4.85 [1.29-18.24]); the presence of HG-AIN (RR 2.50 [1.41-4.45]), and a higher burden of STIs (RR 1.39 [1.03-1.85]) were predictors of rectal HIV-1 shedding intensity. CONCLUSION: The prevalence of HIV-1 RNA rectal shedding is high in virologically suppressed MSM. In addition to ART and the immune system integrity, local factors, including the co-existence of HG-AIN and the burden of STIs, may account for the persistence of HIV-1 RNA shedding in rectal mucosa.

Coinfection with human herpesvirus 8 is associated with persistent inflammation and immune activation in virologically suppressed HIV-infected patients.

OBJECTIVES: Infection with co-pathogens is one of the postulated factors contributing to persistent inflammation and non-AIDS events in virologically-suppressed HIV-infected patients. We aimed to investigate the relationship of human herpesvirus-8 (HHV-8), a vasculotropic virus implicated in the pathogenesis of Kaposi's sarcoma, with inflammation and subclinical atherosclerosis in HIV-infected patients. METHODS: Prospective study including virologically suppressed HIV-infected patients. Several blood biomarkers (highly-sensitive C-reactive protein [hsCRP], tumour necrosis factor-α, interleukin-6, monocyte chemoattractant protein-1, vascular cell adhesion molecule-1, intercellular cell adhesion molecule-1, malondialdehyde, plasminogen activator inhibitor [PAI-1], D-dimer, sCD14, sCD163, CD4/CD38/HLA-DR, and CD8/CD38/HLA-DR), serological tests for HHV-8 and the majority of herpesviruses, carotid intima-media thickness, and endothelial function through flow-mediated dilatation of the brachial artery were measured. RESULTS: A total of 136 patients were included, 34.6% of them infected with HHV-8. HHV-8-infected patients were more frequently co-infected with herpes simplex virus type 2 (HSV-2) (P<0.001), and less frequently with hepatitis C virus (HCV) (P = 0.045), and tended to be older (P = 0.086). HHV-8-infected patients had higher levels of hsCRP (median [interquartile range], 3.63 [1.32-7.54] vs. 2.08 [0.89-4.11] mg/L, P = 0.009), CD4/CD38/HLA-DR (7.67% [4.10-11.86]% vs. 3.86% [2.51-7.42]%, P = 0.035) and CD8/CD38/HLA-DR (8.02% [4.98-14.09]% vs. 5.02% [3.66-6.96]%, P = 0.018). After adjustment for the traditional cardiovascular risk factors, HCV and HSV-2 infection, the associations remained significant: adjusted difference between HHV-8 positive and negative patients (95% confidence interval) for hsCRP, 74.19% (16.65-160.13)%; for CD4/CD38/HLA-DR, 89.65% (14.34-214.87)%; and for CD8/CD38/HLA-DR, 58.41% (12.30-123.22)%. Flow-mediated dilatation and total carotid intima-media thickness were not different according to HHV-8 serostatus. CONCLUSION: In virologically suppressed HIV-infected patients, coinfection with HHV-8 is associated with increased inflammation and immune activation. This might contribute to increase the risk of non-AIDS events, including accelerated atherosclerotic disease.

Long-term effects of an intensive intervention in HIV-infected patients with moderate-high atherosclerotic cardiovascular risk.

OBJECTIVES: To evaluate the 5 year effects of an intensive intervention versus the standard-of-care intervention on cardiovascular risk factors in HIV-infected patients on antiretroviral therapy (ART). METHODS: This was a longitudinal study including virologically suppressed patients with at least two cardiovascular risk factors or a Framingham risk score ≥10%. Intensive and standard-of-care interventions aimed for low-density lipoprotein cholesterol (LDL-C) <100 and <130 mg/dL, respectively, by using lipid-lowering drugs. In the intensive group, switching ART when needed to achieve the LDL-C target and low-dose aspirin were used. Achievement of LDL-C targets and changes in carotid intima-media thickness (cIMT) and cardiovascular biomarkers were compared between groups at different timepoints through a 5 year period. RESULTS: Twenty-two and 25 patients in the intensive and standard intervention groups, respectively, were followed up. At 5 years, pre-specified LDL-C targets were achieved in 82% (intensive) and 81% (standard of care) of patients. The median (IQR) change in LDL-C in the intensive and standard intervention groups was -78 (-96/-39.7) and -49 (-72/-3) mg/dL, respectively (P = 0.04), and in the Framingham score was -4% (-8%/-1%) and 0% (-4%/6.5%), respectively (P = 0.01). There were no significant intra- or between-group changes in cIMT measurements. A significant decrease was observed in the intensive and standard groups in interleukin 6 (P = 0.001 and P = 0.002, respectively) and in tumour necrosis factor α (P = 0.023 and P = 0.052, respectively). Asymptomatic creatine phosphokinase elevations were observed in two patients assigned to the standard intervention group. CONCLUSIONS: An intensive intervention on cardiovascular risk factors in HIV-infected patients on ART was feasible, safe and capable of achieving LDL-C targets in the long term. Both intensive and standard interventions were accompanied by antiatherosclerotic changes in inflammatory cytokines and lack of cIMT progression.

Increased carotid intima-media thickness associated with antibody responses to varicella-zoster virus and cytomegalovirus in HIV-infected patients.

OBJECTIVE: We investigated the relationship of the Herpesviridiae with inflammation and subclinical atherosclerosis in HIV-infected patients. METHODS: Prospective study including virologically suppressed HIV-infected patients. IgG antibodies against herpesviruses, carotid intima-media thickness (cIMT), endothelial function through flow-mediated dilatation (FMD) of the brachial artery, and blood atherosclerosis biomarkers (hsCRP, TNF-α, IL-6, MCP-1, MDA, sCD14, sCD163, VCAM-1, ICAM-1, D-dimer, and PAI-1) were measured. RESULTS: 136 patients with HIV viral load <200 copies/ml were included. 93.4% patients were infected with herpes simplex virus type-1, 55.9% with herpes simplex virus type-2, 97.1% with varicella-zoster virus, 65.4% with human herpesvirus-6, 91.2% with cytomegalovirus, and 99.3% with Epstein-Barr virus. Previous AIDS diagnosis was associated with higher cytomegalovirus IgG titers (23,000 vs 17,000 AU, P = 0.011) and higher varicella-zoster virus IgG titers (3.19 vs 2.88 AU, P = 0.047), and there was a positive correlation of the Framingham risk score with IgG levels against cytomegalovirus (Spearman's Rho 0.216, P = 0.016) and Herpes simplex virus-2 (Spearman's Rho 0.293, P = 0.001). IgG antibodies against cytomegalovirus correlated in adjusted analysis with the cIMT (P = 0.030). High seropositivity for varicella-zoster virus (OR 2.91, 95% CI 1.05-8.01, P = 0.039), and for cytomegalovirus (OR 3.79, 95% CI 1.20-11.97, P = 0.023) were predictors for the highest quartile of the cIMT in adjusted analyses. PAI-1 levels were independently associated with cytomegalovirus IgG titers (P = 0.041), IL-6 and ICAM-1 levels with varicella-zoster virus IgG (P = 0.046 and P = 0.035 respectively), and hsCRP levels with Herpes simplex virus-2 IgG (P = 0.035). CONCLUSION: In virologically suppressed HIV-infected patients, antibody responses against herpesviruses are associated with subclinical atherosclerosis, and with increased inflammation and coagulation biomarkers.

Negative effect of immunosuppressive therapy in the performance of the QuantiFERON gold in-tube test in patients with immune-mediated inflammatory diseases.

To compare the tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube test (QFG) for the detection of latent tuberculosis infection among patients with immune-mediated inflammatory diseases before antitumor necrosis factor-α therapy. A prospective study including 153 consecutive patients with rheumatoid arthritis (n = 53), psoriasis (n = 45), inflammatory bowel disease (n = 25), and spondyloarthropathy (n = 22) were included. QFG and TST were performed simultaneously. TST was positive in 43/153 (28.1 %) patients. QFG (cutoff ≥ 0.35 IU/ml) was positive in 15/153 (9.8 %) patients, and indeterminate in one (0.7 %). QFG (cutoff ≥ 0.10 IU/ml) was positive in 25/153 (16.3 %). 59.5 % of the patients were on immunosuppressive therapy at the time of testing. There was a significant difference in the rate of positive QFG between patients with and without immunosuppressive therapy after adjustment for age and gender (cutoff ≥ 0.35 IU/ml, 4.6 vs. 17.4 %; adjusted odds ratio [AOR], 0.2; 95 % confidence interval [CI], 0.06-0.8; p = 0.03 and cutoff ≥ 0.10 IU/ml, 11.2 vs. 24.2 %; AOR, 0.3; 95 % CI, 0.1-0.93; p = 0.04). Agreement between TST and QFG was 'fair' (κ = 0.354 and κ = 0.365, for cutoffs ≥ 0.35 and ≥0.10 IU/ml, respectively). Among patients without immunosuppressive therapy, the concordance between TST and QFG was 'moderate-substantial' (κ = 0.593 and κ = 0.690, for cutoffs ≥ 0.35 IU/ml and ≥0.10 IU/ml, respectively). By contrast, among patients on immunosuppressive therapy the concordance was 'poor' (κ = 0.085; κ = 0.041, respectively). Immunosuppressive therapy affects negatively QFG performance. In patients with immune-mediated inflammatory diseases, QFG may have a limited role for screening of latent tuberculosis infection.

Contribution of interferon gamma release assays testing to the diagnosis of latent tuberculosis infection in HIV-infected patients: a comparison of QuantiFERON-TB Gold In Tube, T-SPOT.TB and tuberculin skin test.

BACKGROUND: Diagnosis and treatment of latent tuberculosis infection (LTBI) is the most effective strategy to control tuberculosis (TB) among patients with HIV infection. The tuberculin skin test (TST) was the only available method to identify LTBI. The aim of the present work was to evaluate the usefulness of the interferon-gamma release assays (IGRAs): QuantiFERON-tuberculosis (TB) Gold-In-Tube test (QFG) and T-SPOT.TB for the diagnosis of LTBI in a diverse cohort of HIV-infected patients. METHODS: A prospective study was carried out in consecutive patients cared for in a single institution in Spain from January 2009 to October 2010. IGRAs and TST were performed simultaneously. TST induration ≥ 5 mm was considered positive. RESULTS: QFG, T-SPOT.TB and TST were performed in 373 subjects. Median CD4 cell count was 470/µl with a median nadir of 150/µl. TST, QFG and T-SPOT.TB were positive in 13.3%, 7.5% and 18.5% cases respectively. Among 277 patients with neither past or current TB nor previous treatment for LTBI and who had TST results, a positive TST result was obtained in 20 (7.2%) cases. When adding QFG results to TST, there were a total of 26 (8.6%) diagnoses of LTBI. When the results of both IGRAs were added, the number of diagnoses increased to 54 (17.9%) (incremental difference: 10.7% [95% confidence interval [CI]:5.3-16.2%] [p < 0.001]), and when both IGRAs were added, the number of diagnoses reached 56 (18.5%) (incremental difference: 11.3% [95% CI:5.7%-16.9%] [p < 0.001]). Patients with a CD4 cell count greater than 500 cells/µl and prior stay in prison were more likely to have a diagnosis of LTBI by TST and/or QFG and/or T-SPOT.TB (adjusted odds ratio [aOR]: 3.8; 95% CI, 1.4 - 9.9; and aOR: 3.3; 95% CI, 1.3 - 8.3, respectively). CONCLUSIONS: IGRAs were more sensitive than TST for diagnosis of M. tuberculosis infection in HIV-infected patients. Dual sequential testing with TST and IGRAs may be the optimal approach for LTBI screening in this population.

Early changes in parathyroid hormone concentrations in HIV-infected patients initiating antiretroviral therapy with tenofovir.

Initiation of combined antiretroviral therapy (cART) is associated with bone loss, which may be more intense with regimens including tenofovir. The underlying mechanisms are not well understood. Cross-sectional data have linked tenofovir with higher parathyroid hormone (PTH) concentrations in patients with vitamin D deficiency. We performed a longitudinal study with a 48-week follow-up to evaluate sequential changes in PTH and 25-hydroxyvitamin D [25(OH)D] levels in patients starting cART with either tenofovir/emtricitabine or abacavir/lamivudine. Fifty-seven patients were included, 31 initiating tenofovir/emtricitabine and 26 initiating abacavir/lamivudine. Median PTH levels turned out to be significantly higher among tenofovir/emtricitabine users at week 4 (p=0.01), week 24 (p=0.008), and week 36 (p=0.02), and were above the upper limits of normal values (ULN) at weeks 24, 36, and 48 only in patients receiving tenofovir/emtricitabine. 25(OH)D, serum and urine calcium and phosphate, and renal-tubular maximum reabsorption of phosphate to the glomerular filtration rate (TmP/GFR) levels did not differ between the two treatment arms over the study period. Among tenofovir/emtricitabine users, median (interquartile range) PTH concentrations were significantly higher in patients with suboptimal 25(OH)D levels (<30 µg/liter) at week 24 [63 (57.8-82.4) ng/liter vs. 54.3 (34.4-63.067.5) ng/liter, p=0.05] and week 48 [67.5 (59.6-86.0) ng/liter vs. 41.9 (37.3-68.8) ng/liter, p=0.03]. A multivariable logistic regression model showed that tenofovir/emtricitabine use was an independent predictor of high PTH levels (≥53 ng/liter). Starting cART with tenofovir regimens is associated with an elevation in PTH plasma concentrations soon after introducing the drug. Suboptimal baseline 25(OH)D levels increase the risk of developing secondary hyperparathyroidism among tenofovir users.

Evaluation of endothelial function and subclinical atherosclerosis in association with hepatitis C virus in HIV-infected patients: a cross-sectional study.

BACKGROUND: Relationship of hepatitis C virus (HCV) infection with an increased risk of cardiovascular disease (CVD) in HIV-infected patients remains controversial. We evaluated endothelial function and subclinical atherosclerosis in HIV-infected patients with and without HCV. METHODS: Flow-mediated dilatation (FMD) of the brachial artery and circulating levels of cell adhesion molecules (CAM) were measured in HCV/HIV-coinfected and HIV-monoinfected patients. Subclinical atherosclerosis was assessed by carotid intima-media thickness (cIMT). RESULTS: 63 (31%) HCV/HIV-coinfected and 138 (69%) HIV-monoinfected patients were included. Median soluble vascular CAM-1 (sVCAM-1) and intercellular CAM-1 (sICAM-1) levels were significantly higher in HIV/HCV-coinfected patients (P < 0.001 for both cases). Median (interquartile range) FMD was 6.21% (2.86-9.62) in HCV/HIV-coinfected and 5.54% (2.13-9.13) in HIV-monoinfected patients (P = 0.37). Adjustment for variables associated with HCV and FMD disclosed similar results. FMD correlated inversely with cIMT and age. Carotid IMT did not differ between HCV/HIV-coinfected and HIV-monoinfected patients in unadjusted (0.61 [0.55-0.65] mm vs 0.60 [0.53-0.72] mm; P = 0.39) or adjusted analyses. CONCLUSION: HCV infection was associated with higher levels of sICAM-1 and sVCAM-1, but no evidence of increased subclinical atherosclerosis was found when endothelial function was evaluated through FMD, or when assessing the cIMT.

Treatment for hepatitis C virus with pegylated interferon-α plus ribavirin induces anti-atherogenic effects on cardiovascular risk biomarkers in HIV-infected and -uninfected patients.

OBJECTIVES: We investigated the influence of hepatitis C virus (HCV) therapy with pegylated interferon-α plus ribavirin on cardiovascular disease risk through the serial measurement of several laboratory markers in HCV-monoinfected and HCV/HIV-coinfected patients. METHODS: In a longitudinal study, biomarkers of inflammation, coagulation and oxidative stress were measured during and after therapy. RESULTS: A total of 56 patients were included; 32 (57.1%) were HCV/HIV coinfected and 24 (42.9%) were HCV monoinfected. Compared with baseline, during HCV therapy there was a significant decrease in the concentrations of matrix metalloproteinase-9 (P < 0.001), intercellular cell adhesion molecule-1 (ICAM-1) (P ≤ 0.01) and oxidized low-density lipoproteins (P = 0.002). In contrast, levels of vascular cell adhesion molecule-1 (VCAM-1), monocyte chemotactic protein-1 and fibrinogen increased during treatment. After treatment discontinuation, levels of ICAM-1, VCAM-1 and tumour necrosis factor-α were significantly lower compared with baseline, a change restricted to patients with sustained virological response. Decreases in transaminases and HCV-RNA from baseline correlated positively with the decrease in ICAM-1 concentration 6 months after treatment discontinuation. Changes in biomarkers were similar in HIV-infected and -uninfected patients. CONCLUSIONS: Treatment for HCV induces different changes in several cardiovascular risk biomarkers, most being anti-atherogenic effects, although only the anti-atherogenic effects remain after treatment discontinuation in patients with sustained virological response.

Seroprevalence of HTLV infection among immigrant pregnant women in the Mediterranean coast of Spain.

BACKGROUND: Universal HTLV antenatal screening is currently not mandatory in European countries. However, the large number of immigrants coming from HTLV-I endemic areas might force to change this recommendation in the near future. OBJECTIVES: To determine the prevalence of HTLV infections in immigrant pregnant women attended in a general Hospital in the Mediterranean coast of Spain. STUDY DESIGN: From February 2006 to December 2009, a cross-sectional study was carried out on all immigrant pregnant women attended at a reference obstetric unit in Elche, Spain. An enzyme immunoassay (EIA) was used for testing HTLV-I/II antibodies in serum, being reactive samples further confirmed by Western blot. RESULTS: A total of 1439 immigrant pregnant women were examined. Overall, 520 (36.1%) came from Central and South America and 90 (6.2%) from Sub-Saharan Africa, where HTLV infection is endemic. Three samples were EIA-seroreactive for HTLV-1/2. One of them was a woman infected with HTLV-I coming from Brazil and the other two were women infected with HTLV-II coming from Bolivia and Colombia, respectively. Thus, the overall HTLV seroprevalence in the study population was 2.1 per 1000 (95% CI: 0.5-6.6/1000), although it reached to 0.58% in the subset of women from Central and South America. CONCLUSIONS: HTLV antenatal screening should be considered in pregnant women coming from Central and South America, in whom the prevalence of infection is relatively high and avoidance of breastfeeding may effectively prevent vertical HTLV transmission.

A highly sensitive and specific model for predicting HIV-1 tropism in treatment-experienced patients combining interpretation of V3 loop sequences and clinical parameters.

BACKGROUND: Phenotypic assays are considered the gold standard for HIV-1 tropism assessment. However, they are expensive and not widely available. Genotypic assays may provide an easier alternative, but their sensitivity remains low. We hypothesize that combining clinical data with V3 sequences may improve the diagnostic accuracy of genotypic tools. METHODS: We analyzed clinical and biological data from 159 HIV-1-infected adults, 88 (56%) of whom were treatment experienced. Coreceptor phenotype was performed with Trofile and ES Trofile assay. V3 loop sequences were interpreted according to genotypic algorithms available at website. Multivariate logistic regression analyses were used to identify variables predicting HIV-1 tropism. Cut-off values for the prediction of CXCR4-using virus were defined. RESULTS: A total of 170 samples with phenotypic and genotypic determination of HIV-1 tropism were included. When only treatment-experienced patients were selected, a predictive model of HIV-1 tropism had an area under the receiver operating characteristic curve of 0.966 (95% confidence interval: 0.930 to 1.000, P < 0.001). The equation of the model included 2 bioinformatic tools (Geno2pheno-clinical model and net charge rule), the false positive rate score of Geno2pheno, and the following clinical data: exposure to more than 3 antiretroviral classes, years since HIV infection diagnosis and log10 HIV-1 RNA. A cut-off value ≥ 5.75 showed the highest accuracy to predict CXCR4 usage (96.6% sensitivity and 92.3% specificity). CONCLUSIONS: A genotypic-clinical model is highly accurate in predicting phenotypic tropism of HIV-1 in treatment-experienced patients. This may provide a cheap and rapid tool to select candidates for treatment with CCR5 antagonists in a routine clinical setting.

Performance of genotypic algorithms for predicting HIV-1 tropism measured against the enhanced-sensitivity Trofile coreceptor tropism assay.

The objectives of this study were to assess the performance of genotypic algorithms for predicting CXCR4-using virus, with enhanced sensitivity Trofile HIV coreceptor tropism assay (ES Trofile) as the reference, and to compare the concordance/accuracy of genotypic tests with ES Trofile and with the original Trofile assay. Paired phenotypic and genotypic determinations of HIV-1 coreceptor usage were compared in plasma samples from HIV-1-infected patients. Sequencing of the third hypervariable (V3) loop of the viral gene and phenotypic assays were performed for each sample. Genotypic rules used to predict tropism were Geno2pheno (false-positive rate at 1 to 20%), position-specific scoring matrix X4R5 (PSSM(X4R5)) and PSSM(sinsi) (where "sinsi" stands for syncytium inducing and non-syncytium inducing), and the 11/25, 11/24/25, and net charge rules. Two hundred forty-four phenotypic and genotypic samples were tested. Coreceptor usage was obtained from ES Trofile for 145 (59%) samples and from Trofile for 99 (41%) samples. The highest concordance (82.6%) was obtained with PSSM(X4R5) when ES Trofile was used as the reference. Geno2pheno at a 20% false-positive rate showed the highest sensitivity (76.7%) for CXCR4-using virus detection with ES Trofile. Samples from naïve subjects and those with CD4 cell counts between 200 and 500 cells/mm(3) showed the best predictive performance. Overall, the accuracy of the bioinformatics tools to detect CXCR4-using virus was similar for ES Trofile and Trofile; however, the negative predictive values for genotypic tools with ES Trofile were slightly higher than they were with Trofile. The accuracy of genotypic algorithms for detecting CXCR4-using viruses is high when using ES Trofile as the reference. Results are similar to those obtained with Trofile. The concordance with ES Trofile is better with higher CD4 cell counts and nonexposure to antiretroviral therapy.