Pitavastatin versus pravastatin in adults with HIV-1 infection and dyslipidaemia (INTREPID): 12 week and 52 week results of a phase 4, multicentre, randomised, double-blind, superiority trial.

BACKGROUND: People living with HIV-1 infection are at greater risk for cardiovascular disease than seronegative adults. Treatment of dyslipidaemia with statins has been challenging in people with HIV because of an increased potential for drug interactions due to competing cytochrome P450 metabolism between statins and commonly used antiretroviral agents. Neither pitavastatin nor pravastatin depend on cytochrome P450 for primary metabolism. We aimed to assess the safety and efficacy of pitavastatin versus pravastatin in adults with HIV and dyslipidaemia. METHODS: In the INTREPID (HIV-infected patieNts and TREatment with PItavastatin vs pravastatin for Dyslipidemia) randomised, double-blind, active-controlled, phase 4 trial (INTREPID, we recruited adults aged 18-70 years with controlled HIV (with CD4 counts >200 cells per µL and HIV-1 RNA <200 copies per mL) on antiretroviral therapy for at least 6 months and dyslipidaemia (LDL cholesterol 3·4-5·7 mmol/L and triglycerides ≤4·5 mmol/L) from 45 sites in the USA and Puerto Rico. Patients being treated with darunavir, or who had homozygous familial hypercholesterolaemia or any condition causing secondary dyslipidaemia, or a history of statin intolerance, diabetes, or coronary artery disease were not eligible. We randomly assigned patients (1:1) to pitavastatin 4 mg or pravastatin 40 mg with matching placebos once daily orally for 12 weeks, followed by a 40 week safety extension. Randomisation was stratified by viral hepatitis B or C coinfection and computer-generated. Investigators, patients, study staff, and those assessing outcomes were masked to treatment group. The primary endpoint was percentage change in fasting serum LDL cholesterol from baseline to week 12 and the primary efficacy analysis was done in the modified intention-to-treat population. The safety analysis included all patients who took at least one dose of study medication. This study is registered with ClinicalTrials.gov, number NCT01301066. FINDINGS: Between Feb 23, 2011, and March 29, 2013, we randomly assigned 252 patients to the pitavastatin (n=126) or pravastatin group (n=126). LDL cholesterol reduction was 31·1% with pitavastatin and 20·9% with pravastatin (least squares mean difference -9·8%, 95% CI -13·8 to -5·9; p<0·0001) at 12 weeks. At week 52, four patients (3%) in the pitavastatin group and six (5%) in the pravastatin group had virological failure, with no significant difference between treatments. Both treatments had neutral effects on glucose metabolism parameters. 85 patients treated with pitavastatin (68%) and 88 patients treated with pravastatin (70%) reported treatment-emergent adverse events, and these caused study discontinuation in six patients (5%) versus five patients (4%). No serious adverse event occurred in more than one participant and none were treatment-related according to investigator assessment. The most common treatment-emergent adverse events were diarrhoea in the pitavastatin group (n=12, 10%) and upper respiratory tract infection in the pravastatin group (n=14, 11%). 11 treatment-emergent serious adverse events were noted in seven patients (6%) in the pitavastatin group (atrial septal defect, chronic obstructive pulmonary disease, chest pain, diverticulitis, enterovesical fistula, gastroenteritis, viral gastroenteritis, herpes dermatitis, multiple fractures, respiratory failure, and transient ischaemic attack) and four events in three patients (2%) in the pravastatin group (cerebrovascular accident, arteriosclerosis coronary artery, myocardial infraction, and muscle haemorrhage). In the pravastatin treatment group, one additional patient discontinued due to an adverse event (prostate cancer that was diagnosed during the screening period, 42 days before first dose of study treatment, and therefore was not a treatment-emergent adverse event). INTERPRETATION: The INTREPID results support guideline recommendations for pitavastatin as a preferred drug in the treatment of dyslipidaemia in people with HIV. FUNDING: Kowa Pharmaceuticals America and Eli Lilly and Company.

Five Antiretroviral Drug Class-Resistant HIV-1 in a Treatment-Naïve Patient Successfully Suppressed with Optimized Antiretroviral Drug Selection.

Transmitted HIV-1 exhibiting reduced susceptibility to protease and reverse transcriptase inhibitors is well documented but limited for integrase inhibitors and enfuvirtide. We describe here a case of transmitted 5 drug class-resistance in an antiretroviral (ARV)-naïve patient who was successfully treated based on the optimized selection of an active ARV drug regimen. The value of baseline resistance testing to determine an optimal ARV treatment regimen is highlighted in this case report.

Trends in Decline of Antiretroviral Resistance among ARV-Experienced Patients in the HIV Outpatient Study: 1999-2008.

Background. Little is known about temporal trends in frequencies of clinically relevant ARV resistance mutations in HIV strains from U.S. patients undergoing genotypic testing (GT) in routine HIV care. Methods. We analyzed cumulative frequency of HIV resistance among patients in the HIV Outpatient Study (HOPS) who, during 1999-2008 and while prescribed antiretrovirals, underwent GT with plasma HIV RNA >1,000 copies/mL. Exposure ≥4 months to each of three major antiretroviral classes (NRTI, NNRTI and PI) was defined as triple-class exposure (TCE). Results. 906 patients contributed 1,570 GT results. The annual frequency of any major resistance mutations decreased during 1999-2008 (88% to 79%, P = 0.05). Resistance to PIs decreased among PI-exposed patients (71% to 46%, P = 0.010) as exposure to ritonavir-boosted PIs increased (6% to 81%, P < 0.001). Non-significant declines were observed in resistance to NRTIs among NRTI-exposed (82% to 67%), and triple-class-resistance among TCE patients (66% to 41%), but not to NNRTIs among NNRTI-exposed. Conclusions. HIV resistance was common but declined in HIV isolates from subgroups of ARV-experienced HOPS patients during 1999-2008. Resistance to PIs among PI-exposed patients decreased, possibly due to increased representation of patients whose only PI exposures were to boosted PIs.

Simplification of antiretroviral therapy to a single-tablet regimen consisting of efavirenz, emtricitabine, and tenofovir disoproxil fumarate versus unmodified antiretroviral therapy in virologically suppressed HIV-1-infected patients.

OBJECTIVE: To evaluate a simplification strategy for HIV-1-infected patients virologically suppressed on antiretroviral therapy (ART) by switching to a single-tablet regimen consisting of efavirenz/emtricitabine/tenofovir disoproxil fumarate (EFV/FTC/TDF). DESIGN: : Prospective, randomized, controlled, open-label, multicenter study. METHODS: Patients on stable ART with HIV-1 RNA <200 copies per milliliter for > or = 3 months were stratified by prior nonnucleoside reverse transcriptase inhibitor-based or protease inhibitor-based therapy and randomized (2:1) to simplify treatment to EFV/FTC/TDF or to stay on their baseline regimen (SBR). Efficacy and safety assessments were performed at baseline and at weeks 4, 12, 24, 36, and 48. Additional patient-reported outcomes included the following: adherence by visual analog scale, quality of life by SF-36 (v2) survey, HIV Symptom Index, and the Preference of Medication and Perceived Ease of the Regimen for Condition questionnaires. RESULTS: Three hundred patients (EFV/FTC/TDF 203, SBR 97) were evaluated (prior protease inhibitor-based ART, 53%; nonnucleoside reverse transcriptase inhibitor-based ART, 47%). The arms were well balanced at baseline with 88% males, 29% blacks, and a mean age of 43 years; CD4 was 540 cells per cubic millimeter, 96% had HIV-1 RNA <50 copies per milliliter, and 88% were on their first ART regimen. Through 48 weeks, 89% vs. 88% in the EFV/FTC/TDF vs. SBR arms, respectively, maintained HIV-1 RNA <200 copies per milliliter by time to loss of virologic response algorithm (intent to treat, noncompleters = failures) with the difference (95% confidence interval) between arms of 1.1% (-6.7% to 8.8%), indicating noninferiority of EFV/FTC/TDF vs. SBR. Similarly, maintenance of HIV-1 RNA <50 copies per milliliter by time to loss of virologic response algorithm was 87% vs. 85% for EFV/FTC/TDF vs. SBR, respectively [difference (95% confidence interval) 2.6% (-5.9% to 11.1%)]. Discontinuation rates were similar (EFV/FTC/TDF 11%, SBR 12%); more discontinuations for adverse events occurred in the EFV/FTC/TDF arm vs. SBR (5% vs. 1%), most commonly for nervous system symptoms. More patients withdrew consent in the SBR arm vs. EFV/FTC/TDF (7% vs. 2%). Estimated glomerular filtration rate (by Modification of Diet in Renal Disease) remained unchanged over 48 weeks in both arms (median change < 1 mL.min.1.73 m). A decrease in fasting triglycerides was observed at 48 weeks in the EFV/FTC/TDF vs. SBR arm (-20 vs. -3.0 mg/dL; P = 0.035). Adherence of > or = 96% was reported by visual analog scale in both arms at baseline and at all study visits. CONCLUSION: Simplification to EFV/FTC/TDF maintained high and comparable rates of virologic suppression vs. SBR through 48 weeks.

Gemini: a noninferiority study of saquinavir/ritonavir versus lopinavir/ritonavir as initial HIV-1 therapy in adults.

INTRODUCTION: : Direct comparison of the efficacy and safety of different agents is needed to guide selection of optimal treatment regimens for therapy-naive HIV-1-infected patients. METHODS: : Gemini was a 48-week, multicenter, open-label, noninferiority trial in treatment-naive HIV-1-infected adults randomized to either saquinavir/ritonavir (SQV/r) 1000 mg/100 mg twice a day or lopinavir/ritonavir (LPV/r) 400 mg/100 mg twice a day, each with emtricitabine/tenofovir 200 mg/300 mg every day. RESULTS: : A similar proportion of participants in the SQV/r (n = 167) and LPV/r (n = 170) arms had HIV-1 RNA levels <50 copies per milliliter at week 48: 64.7% vs 63.5% and estimated difference in proportion for noninferiority: 1.14%, 96% confidence interval: -9.6 to11.9 (P < 0.012), confirming that SQV/r was noninferior to LPV/r treatment. There were no significant differences in week 48 CD4 counts between arms. The rate and severity of adverse events were similar in both groups. There were no significant differences in the median change from baseline between arms in plasma lipids except for triglyceride levels, which were significantly higher in the LPV/r at week 48. CONCLUSIONS: : In treatment-naive, HIV-1-infected patients, SQV/r treatment was noninferior in virologic suppression at 48 weeks to LPV/r treatment and offered a better triglyceride profile.

Persistence of HIV in gut-associated lymphoid tissue despite long-term antiretroviral therapy.

Human immunodeficiency virus (HIV) persists in peripheral blood mononuclear cells despite sustained, undetectable plasma viremia resulting from long-term antiretroviral therapy. However, the source of persistent HIV in such infected individuals remains unclear. Given recent data suggesting high levels of viral replication and profound depletion of CD4(+) T cells in gut-associated lymphoid tissue (GALT) of animals infected with simian immunodeficiency virus and HIV-infected humans, we sought to determine the level of CD4(+) T cell depletion as well as the degree and extent of HIV persistence in the GALT of infected individuals who had been receiving effective antiviral therapy for prolonged periods of time. We demonstrate incomplete recoveries of CD4(+) T cells in the GALT of aviremic, HIV-infected individuals who had received up to 9.9 years of effective antiretroviral therapy. In addition, we demonstrate higher frequencies of HIV infection in GALT, compared with PBMCs, in these aviremic individuals and provide evidence for cross-infection between these 2 cellular compartments. Together, these data provide a possible mechanism for the maintenance of viral reservoirs revolving around the GALT of HIV-infected individuals despite long-term viral suppression and suggest that the GALT may play a major role in the persistence of HIV in such individuals.

Treatment response to ritonavir-boosted tipranavir versus ritonavir-boosted lopinavir in HIV-1 patients with higher lopinavir mutation scores.

Week 48 HIV-RNA treatment response to the protease inhibitor tipranavir co-administered with ritonavir was compared with that of lopinavir co-administered with ritonavir in patients whose baseline isolates had varying lopinavir genotypic mutation scores. With increasing lopinavir mutation scores, the proportion of patients achieving a week 48 treatment response was increased in the tipranavir/ritonavir compared with the lopinavir/ritonavir arm. Tipranavir/ritonavir therapy improves treatment response rates compared with lopinavir/ritonavir in patients whose viruses have reduced susceptibility to lopinavir/ritonavir.

Preliminary safety and efficacy data of brecanavir, a novel HIV-1 protease inhibitor: 24 week data from study HPR10006.

BACKGROUND: Brecanavir, a novel protease inhibitor (PI), has sub-nM in vitro antiviral activity against multi-PI-resistant HIV-1 and in vitro is >100-fold more potent than previously marketed PIs and approx. 10-fold more potent than the recently marketed PI, darunavir. METHODS: HPR10006 is an open label, single-arm, descriptive 48 week study, with 8 and 24 week interim analyses. Thirty-one HIV-1-infected patients were enrolled and received brecanavir/ritonavir 300 mg/100 mg twice daily, with two nucleoside reverse transcriptase inhibitors, based on history and genotype. RESULTS: At baseline, 25/31 had PI-sensitive virus and 6/31 had PI-resistant virus (median of two primary PI and five secondary PI mutations). Median baseline HIV-1 RNA was 5.0 and 4.2 log(10) copies/mL, respectively. Four patients discontinued prior to Week 24. At Week 24, 77% (24/31) had HIV-1 RNA <50 copies/mL regardless of screening genotype, including 5/6 patients with PI-resistant virus (6/6 had HIV-1 RNA <400 copies/mL). Brecanavir/ritonavir was well tolerated with no serious adverse events or clinically concerning changes in laboratory parameters. Of 31 patients, 10 (32%) experienced drug-related Grade 2-4 adverse events [most frequent events were fatigue (13%), dyspepsia (10%) and nausea (10%)]. Baseline isolate brecanavir IC(50) values for all patients ranged from 0.1 to 0.2 nM. Median plasma trough concentration at Week 4 was 150 ng/mL. Correcting the IC(50) (0.2 nM) value for protein binding (6-fold increase in vitro with 50% human serum) gives a corrected inhibitory quotient of 180. CONCLUSIONS: Brecanavir/ritonavir was well tolerated and showed potent antiviral activity in HIV-1-infected patients harbouring both PI-sensitive and PI-resistant virus, following 24 weeks of dosing.

Pilot study of once-daily simplification therapy with abacavir/lamivudine/zidovudine and efavirenz for treatment of HIV-1 infection.

OBJECTIVE: The purpose of this pilot study was to explore the efficacy and safety of the abacavir/lamivudine/zidovudine fixed-dose combination tablet administered as two tablets once daily (qd) versus one tablet twice daily (bid) in combination with efavirenz (EFV). METHOD: This was a prospective, randomized, open-label, multicenter study with a 24-week treatment period in 7 outpatient HIV clinics in the United States. Patients currently receiving an initial regimen of abacavir/lamivudine/zidovudine bid plus EFV qd for at least 6 months with HIV-1 RNA <50 copies/mL for at least 3 months and a screening CD4+ cell count > or = 200 cells/mm3 were eligible. Thirty-six patients enrolled, and 35 (97%) completed the study. Participants were randomized to switch to 2 tablets of abacavir/lamivudine/zidovudine qd plus EFV qd (QD arm) or continue current treatment (BID arm) for 24 weeks. RESULTS: Efficacy, safety, and adherence were evaluated. Median baseline CD4+ cell count was 521 cells/mm3. At week 24, HIV-1 RNA <50 copies/mL was achieved for 94% of participants in the QD arm and 89% in the BID arm by intent-to-treat, missing = failure analysis (95% confidence interval for difference: > or = 0.29 to +0.18, p = 1.000). At week 24, median CD4+ cell count change from baseline was +26 cells/mm3 for the QD arm and -39 cells/mm3 for BID arm. One patient randomized to the QD arm met virologic failure criteria (confirmed HIV-1 RNA >120 copies/mL) at week 20 and viral genotype showed M184V. After failure, this patient revealed he never took EFV throughout the entire study after randomization, effectively receiving only abacavir/lamivudine/zidovudine qd alone. Median adherence was slightly higher in the QD arm, although both arms had broad variability and overlapping interquartile ranges. Adverse events were infrequent and occurred with similar frequency between arms; treatment-related adverse events were abdominal pain, flatulence, nausea, headache, and abnormal dreams (1 patient [3%] for each adverse event). No patients withdrew due to adverse events, and no abacavir hypersensitivity reactions were reported. CONCLUSION: In this pilot study of patients suppressed on abacavir/lamivudine/zidovudine bid plus EFV, 94% of participants switching to abacavir/lamivudine/zidovudine qd plus EFV maintained virologic suppression, compared to 89% of participants continuing abacavir/lamivudine/zidovudine bid plus EFV.

Switch from efavirenz to nevirapine associated with resolution of efavirenz-related neuropsychiatric adverse events and improvement in lipid profiles.

In a large HIV-specialty private practice, patients with undetectable or low-grade-positive viral loads with neuropsychiatric side effects or elevated lipids were switched from efavirenz-to nevirapine-based antiretroviral regimens. This is a retrospective analysis of virologic efficacy and changes in adverse neuropsychiatric effects and serum lipid levels after this switch. Forty patients were evaluated. Thirty-six had undetectable viral loads prior to the treatment switch, and their levels remained undetectable after the switch for a median of 25 months (range, 6 to 59 months). Four patients had persistently low-grade-positive viral loads before the switch; viral loads in two of the four patients remained low-grade-positive, while the levels in two patients became undetectable. Twenty patients reporting neuropsychiatric symptoms (depression, anxiety, or fatigue with or without sleep disturbances) before the switch demonstrated significant improvement, with complete resolution of symptoms in 15 patients. Four patients with isolated sleep disturbances had significant improvement. No rash developed in any patient during the switch. Mean lipid levels improved significantly following the switch. Mean total cholesterol decreased 17.8 mg/dL; low-density lipoprotein cholesterol decreased 25.5 mg/dL; triglycerides decreased 70.1 mg/dL; and high-density lipoprotein cholesterol increased 5.3 mg/dL (all p < 0.05). These results demonstrate that patients who are virologically controlled on efavirenz-containing regimens with treatment-associated side effects can be successfully switched to nevirapine-containing therapy with maintenance of virologic control, reduction in neuropsychiatric side effects, and improvement in dyslipidemia.

HIV-infected individuals receiving effective antiviral therapy for extended periods of time continually replenish their viral reservoir.

The persistence of latently infected, resting CD4+ T cells is considered to be a major obstacle in preventing the eradication of HIV-1 even in patients who have received effective antiviral therapy for an average duration of 5 years. Although previous studies have suggested that the latent HIV reservoir in the resting CD4+ T cell compartment is virologically quiescent in the absence of activating stimuli, evidence has been mounting to suggest that low levels of ongoing viral replication persist and in turn, prolong the overall half-life of HIV in patients receiving antiviral therapy. Here, we demonstrate the persistence of replication-competent virus in CD4+ T cells in a cohort of patients who had received uninterrupted antiviral therapy for up to 9.1 years that rendered them consistently aviremic throughout that time. Surprisingly, substantially higher levels of HIV proviral DNA were found in activated CD4+ T cells when compared with resting CD4+ T cells in the majority of patients we studied. Phylogenetic analyses revealed evidence for cross infection between the resting and activated CD4+ T cell compartments, suggesting that ongoing reactivation of latently infected, resting CD4+ T cells and spread of virus by activated CD4+ T cells may occur in these patients. Such events may allow continual replenishment of the CD4+ T cell reservoir and resetting of the half-life of the latently infected, resting CD4+ T cells despite prolonged periods of aviremia.

Lack of recurrence of hyperlactatemia in HIV-infected patients switched from stavudine to abacavir or zidovudine.

Stavudine (d4T) has been observed in clinical trials and cohort studies to be more often implicated in cases of hyperlactatemia than other nucleoside reverse transcriptase inhibitors, possibly because of its relatively greater propensity to induce mitochondrial toxicity. The ESS40010 study was a 48-week, open-label, switch study that assessed changes in serum lactate levels and signs/symptoms of hyperlactatemia after substitution of abacavir (n = 86) or zidovudine (n = 32) for d4T in 118 virologically suppressed HIV-infected patients (HIV-1 RNA <400 copies/mL) who had developed serum lactate concentrations > or =2.2 mmol/L (n = 16) or had remained normolactatemic (n = 102) after receiving > or =6 months of d4T-based treatment. Median serum lactate decreased significantly below baseline at week 24 (-0.15 mmol/L, P = 0.0002) and week 48 (-0.15 mmol/L, P = 0.0015). In 10 hyperlactatemic patients in whom d4T was discontinued, serum HIV-1 RNA levels rebounded over the ensuing 31 days, but virologic suppression (HIV-1 RNA <400 copies/mL) was regained when treatment using abacavir or zidovudine was subsequently instituted. In the group with elevated lactate at baseline, symptoms of hyperlactatemia improved in 8% to 23% of patients, did not change in 69%, and worsened in 8%. Serum transaminases, which had been elevated while patients received d4T, normalized after d4T discontinuation and remained in the normal range after the switch to abacavir or zidovudine. Overall, in patients with d4T-associated hyperlactatemia, stopping d4T results in normalization of lactate and a rebound in viral load; restarting treatment using abacavir or zidovudine subsequently maintains normal lactate levels and rapidly leads to a return of virologic suppression.

Improvement in lipoatrophy associated with highly active antiretroviral therapy in human immunodeficiency virus-infected patients switched from stavudine to abacavir or zidovudine: the results of the TARHEEL study.

Stavudine use is a contributing factor for lipoatrophy, whereas use of abacavir or zidovudine is less likely to cause this complication. The TARHEEL study was a 48-week, open-label study that assessed changes in lipoatrophy after abacavir (86 patients [73%]) or zidovudine (32 patients [27%]), 300 mg twice daily, was substituted for stavudine for 118 human immunodeficiency virus (HIV)-infected patients (HIV type 1 RNA level, <400 copies/mL) with virological suppression who had developed lipoatrophy after > or =6 months of stavudine-based treatment. At week 48, full-body dual-energy x-ray absorptiometry demonstrated a median increase in arm fat of 35%, leg fat of 12%, and trunk fat of 18%, compared with the baseline level. These improvements coincided with fat gain in lipoatrophic areas that was documented by computerized tomography. Results of a "body image" questionnaire showed that a substantial percentage of patients reported some or a lot of fat gain in the arms (22%), legs (18%), buttocks (19%), and face (27%). HIV suppression was maintained over the study period. In conclusion, replacing stavudine with abacavir or zidovudine resulted in improvement in stavudine-induced lipoatrophy.

Incidence of and risk factors for lipoatrophy (abnormal fat loss) in ambulatory HIV-1-infected patients.

To identify clinical factors associated with the incidence of HIV-1-associated lipoatrophy, HIV-1-infected patients in the HIV Outpatient Study (HOPS) were prospectively evaluated for clinical signs of lipoatrophy at two visits about 21 months apart. Development of lipoatrophy was analyzed in stratified and multivariate analyses for its relationship to immunologic, virologic, clinical, and drug treatment information for each patient. Of 337 patients with no lipoatrophy at Survey 1, 44 (13.1%) developed moderate or severe lipoatrophy between the two surveys. In multivariate analyses, significant risk factors for incident lipoatrophy were white race (OR = 5.2; 95% CI: 1.9-17.1; =.003), CD4 T-lymphocyte count at Survey 2 less than 100 cells/mm3 (OR = 4.2; 95% CI: 1.3-13.1; =.013), and body mass index (BMI) less than 24 kg/m2 (OR = 2.4; 95% CI: 1.1-5.4; =.024). Analyses that controlled for the severity of HIV illness demonstrated no significant association with use of or time on any antiretroviral agent or class of agents and the development of lipoatrophy. Some host factors and factors associated with previous or current severity of HIV infection, especially CD4 T-lymphocyte cell count, appeared to have the strongest association with incidence of lipoatrophy.

Protease inhibitors and cardiovascular outcomes in patients with HIV-1.

Protease inhibitors for treatment of HIV-1 have been linked with increased risk of hyperlipidaemia and hyperglycaemia. In a cohort of 5672 outpatients with HIV-1 seen at nine US HIV clinics between January, 1993, and January, 2002, the frequency of myocardial infarctions increased after the introduction of protease inhibitors in 1996 (test for trend, p=0.0125). We noted that 19 of 3247 patients taking, but only two of 2425 who did not take, protease inhibitors had a myocardial infarction (odds ratio 7.1, 95% CI 1.6-44.3; Cox proportional hazards model-adjusted for smoking, sex, age, diabetes, hyperlipidaemia, and hypertension-hazard ratio 6.5, 0.9-47.8). Our findings suggest that, although infrequent, use of protease inhibitors is associated with increased risk of myocardial infarction in patients with HIV-1.

Prevalence and clinical correlates of HIV viremia ('blips') in patients with previous suppression below the limits of quantification.

OBJECTIVE: To examine the prevalence and clinical correlates of subsequently measurable viremia in HIV-infected patients who have achieved viral suppression below the limits of quantification (< 50 copies/ml). DESIGN: Non-randomized dynamic cohort study of ambulatory HIV patients in nine HIV clinics in eight cities. PATIENTS: Patients had two consecutive HIV-1 RNA levels < 50 copies/ml (minimum, 2 months apart) that were followed by at least two more viral level determinations while remaining on the same antiretroviral therapy (ART) between January 1997 and June 2000 (median 485 days). Transiently viremic patients were defined having a subsequently measurable viremia but again achieved suppression < 50 copies/ml. RESULTS: Of the 448 patients, 122 (27.2%) had transient viremia, 19 (4.2%) had lasting low-level viremia and 33 (7.4%) had lasting high-level viremia (defined as 50-400 and > 400 copies/ml, respectively). Only 16 (13.1%) of those who had transient viremia later had persistent viremia > 50 copies/ml. The occurrence of transient viremia did not vary with whether the patient was ART-naive or experienced (P = 0.31), or currently taking protease inhibitors or not (P = 0.08). On consistent ART, the median percentage increase in CD4 cell count was statistically different between subgroups of our cohort (Kruskal-Wallis, P = 0.002). CONCLUSIONS: Transiently detectable viremia, usually 50-400 copies/ml, was frequent among patients who had two consecutive HIV-1 RNA levels below the limits of quantification. In this analysis, such viremia did not appear to affect the risk of developing lasting viremia. Caution is warranted before considering a regimen as 'failing' and changing medications.