Incidence of abacavir hypersensitivity reactions in euroSIDA

BACKGROUND

The aim of the study was to investigate the incidence of abacavir-related hypersensitivity reaction (HSR) and associated deaths in EuroSIDA HIV-1-infected patients.

METHODS

Poisson regression models were developed to compare incidence of abacavir discontinuation according to the line of therapy within which abacavir was received, geographical regions, calendar time and drug formulation (abacavir/lamivudine combination tablet versus abacavir as a single drug or abacavir/zidovudine/lamivudine combination).

RESULTS

Of 3,278 patients that started abacavir, 2,101 (64.1%) discontinued. Of these, 167 (5.1%) discontinued abacavir within 3 months due to HSR with an incidence of 22.1 (95% confidence interval [CI] 18.7-25.4) per 100 person-years of follow-up. After adjustment for gender, prior AIDS, hepatitis C serostatus, baseline CD4+ T-cell count, region and calendar time, HSR incidence was significantly higher in those starting abacavir in a first-line regimen compared with second-line (incidence rate ratio [IRR] 2.04 [95% CI 1.24-3.38]; P=0.005). There was no significant difference between regions. HSR incidence from 2005 onwards was significantly lower compared with 1999-2000 (IRR 0.54 [95% CI 0.32-0.92]; P=0.024). There was a lower observed incidence in patients starting abacavir/lamivudine compared with other formulations (IRR 0.33 [95% CI 0.13-0.88]; P=0.027), however, available data were limited.

CONCLUSIONS

Incidence of abacavir-related HSR is higher in patients starting abacavir in first-line therapy, which could indicate increased over-diagnosis. HSR incidence has decreased in recent years, which might reflect the wider availability of genetic screening and improved awareness of symptoms. There were no reported deaths due to abacavir HSR.

Modelled in vivo HIV fitness under drug selective pressure and estimated genetic barrier towards resistance are predictive for virological response

BACKGROUND

A method has been developed to estimate a fitness landscape experienced by HIV-1 under treatment selective pressure as a function of the genotypic sequence thereby also estimating the genetic barrier to resistance.

METHODS

We evaluated the performance of two estimated fitness landscapes (nelfinavir [NFV] and zidovudine [AZT] plus lamivudine [3TC]) to predict week 12 viral load (VL) change for 176 treatment change episodes (TCEs) and probability of week 48 virological failure for 90 TCEs, in treatment experienced patients starting these drugs in combination.

RESULTS

A higher genetic barrier for AZT plus 3TC, (quantified per additional mutation required to develop resistance against these drugs) was associated with a 0.54 (95% confidence interval [CI] 0.30-0.77) larger log10 VL reduction at 12 weeks (P < 0.0001) and a 0.39 (95%/ CI 0.23-0.66) lower odds of virological failure at 48 weeks (P = 0.0005), in analyses adjusting for the pre-TCE VL and the exact time-lag between the TCE and the date of determining response VL. The strength of these associations was comparable with those seen with expert interpretation systems (Rega, ANRS and HIVDB). A higher genetic barrier to NFV resistance was the only genotypic predictor that tended to be associated with a 0.19 (95% CI 0-0.39) higher log10 VL reduction at 12 weeks (P = 0.05) and a 0.63 (95% CI 0.36-1.09) lower odds of virological failure at 48 weeks ( P = 0.10) per additional mutation.

CONCLUSIONS

These results suggest that an estimated genetic barrier derived from fitness landscapes may contribute to an improvement of predicted treatment outcome for NFV and this approach should be explored for other drugs.

Pharmacokinetics of two randomized trials evaluating the safety and efficacy of indinavir, saquinavir and lopinavir in combination with low-dose ritonavir: the MaxCmin1 and 2 trials

Our objective was to identify possible differences in protease inhibitor plasma concentrations between and within three protease inhibitor regimens (indinavir, saquinavir and lopinavir all in combination with low-dose ritonavir) and to relate these differences to safety and efficacy. Data originated from pre-defined pharmacokinetic substudies within two randomized 48-week trials evaluating the safety and efficacy of three protease inhibitor regimens. At weeks 4 and 48, plasma was collected and minimum drug plasma concentrations, C(min), were obtained. Out of 656 randomized patients, 283 patients had available C(min) at week 4. Indinavir, saquinavir and lopinavir C(min) were high when combined with low-dose ritonavir. No significant difference in the proportion of patients experiencing treatment failure could be found according to the C(min) within any treatment arm. A saquinavir C(min) > 2000 ng/ml was associated with an increased risk of gastrointestinal grade 3 or 4 adverse events and higher total cholesterol. Overall, there were no changes in C(min) from week 4 to week 48 in patients who remained on therapy. No association between treatment failure and the C(min) could be demonstrated. Associations between high C(min) and toxicity were identified in the saquinavir arm; therefore, dose reductions may be appropriate in certain patients with C(min) several times above the minimum effective concentration.

Predictors of CD4 count change over 8 months of follow up in HIV-1-infected patients with a CD4 count>or=300 cells/microL who were assigned to 7.5 MIU interleukin-2

BACKGROUND

ESPRIT is a randomized trial comparing the clinical impact of interleukin (IL)-2 plus antiretrovirals vs antiretrovirals alone. Identification of factors that influence the relationship between IL-2 and CD4 count recovery will enable better personalization of treatment with IL-2 in HIV-1-positive individuals. The IL-2 induction phase consists of three dosing cycles over 6-8 months (7.5 MIU twice a day, for 5 days every 8 weeks).

METHODS

We included patients initiating IL-2 at the 7.5 MIU dose with an 8-month CD4 count, measured at least 30 days after their last cycle. We identified baseline predictors of CD4 count changes over 8 months using linear regression.

RESULTS

Of 2090 patients assigned IL-2, 1673 (80%) were included in the analysis. The median (interquartile range) baseline CD4 count was 461 (370, 587) cells/microL with a median increase of 233 (90, 411) cells/microL at month 8. After adjustments, significant predictors of CD4 count change included CD4 nadir (29.8 cells/microL greater increase per 100 cells/microL higher; P<0.0001), last CD4 count before baseline (mean 36.0 cells/microL greater increase per 100 cells/microL higher; P<0.0001), time from antiretroviral start to baseline (8.3 cells/microL smaller increase per year longer; P=0.001), age (11.7 cells/microL smaller increase per 5 years older; P=0.005) and race (79.7 cells/microL greater increase for black patients vs white patients; P=0.003). A linear relationship existed between total IL-2 dose in the first cycle and CD4 count change (73.1 cells/microL greater increase per 15 MIU higher; P<0.0001).

CONCLUSIONS

Prior nadir and current CD4 counts, age and IL-2 dose are major determinants of CD4 increases induced by with intermittent administration of IL-2 in HIV-1-positive individuals on antiretrovirals. The clinical function of these induced CD4 cells is under study.

The ability of four genotypic interpretation systems to predict virological response to ritonavir-boosted protease inhibitors

BACKGROUND

: Limited information exists on the prognostic value of genotypic interpretation systems (GISs) for ritonavir-boosted protease inhibitors (PI/rs). We compared PI/r resistance levels ascribed by four GIS and examined their abilities to predict HIV-RNA reductions after starting a PI/r-based regimen (baseline).

METHODS

: Data on viraemic (HIV-RNA > 500 copies/ml) patients starting a PI/r with a baseline resistance test were combined from an observational cohort study (EuroSIDA) and three randomized trials (MaxCmin1; MaxCmin2 and COLATE). The GIS surveyed were ANRS, DMC, REGA and Stanford. Factors associated with HIV-RNA change were identified through censored regression analysis.

RESULTS

: We included 744 patients, of whom 67% were PI experienced. At baseline 12-28% (depending on the GIS) patients had a virus with predicted resistance/intermediate resistance to the PI/r initiated. Concordance between GISs on ascribed PI/r resistance levels was moderate: kappa values ranged from 0.01 to 1.00, with the lowest kappas seen for amprenavir. The median (interquartile range) baseline HIV-RNA was 4.4 (3.5-5.1) log10 and was reduced by 2.2 (2.1-2.3) log10 12 (9-13) weeks after baseline. GIS consistently showed greater HIV-RNA reductions as the ascribed level of sensitivity to the PI/r increased. Conversely, the number of other active drugs in the rest of the regimen, according to each GIS did not predict HIV-RNA reductions consistently.

CONCLUSION

: Despite large variations in how GIS classify HIV susceptibility to PI/r, all GIS predicted HIV-RNA reductions of a similar magnitude. The ascribed level of susceptibility to other drugs in the regimen did not predict HIV-RNA decline.

Short-term clinical disease progression in HIV-1-positive patients taking combination antiretroviral therapy: the EuroSIDA risk-score

OBJECTIVES

To derive and validate a clinically applicable prognostic score for predicting short-term disease progression in HIV-infected patients taking combination antiretroviral therapy (cART).

DESIGN AND METHODS

Poisson regression was used to identify prognostic markers for new AIDS/death in patients taking cART. A score was derived for 4169 patients from EuroSIDA and validated on 5150 patients from the Swiss HIV Cohort Study (SHCS).

RESULTS

In EuroSIDA, 658 events occurred during 22 321 person-years of follow-up: an incidence rate of 3.0/100 person-years of follow-up [95% confidence interval (CI), 2.7-3.3]. Current levels of viral load, CD4 cell count, CD4 cell slope, anaemia, and body mass index all independently predicted new AIDS/death, as did age, exposure group, a prior AIDS diagnosis, prior antiretroviral treatment and stopping all antiretroviral drugs. The EuroSIDA risk-score was divided into four strata; a patient in the lowest strata would have predicted chance of new AIDS/death of 1 in 801, 1 in 401 and 1 in 201 within the next 3, 6 or 12 months, respectively. The corresponding figures for the highest strata were 1 in 17, 1 in 9 and 1 in 5, respectively. A single-unit increase in the risk-score was associated with a 2.70 times higher incidence of clinical progression (95% CI, 2.56-2.84) in EuroSIDA and 2.88 (95% CI, 2.75-3.02) in SHCS.

CONCLUSIONS

A clinically relevant prognostic score was derived in EuroSIDA and validated within the SHCS, with good agreement. The EuroSIDA risk-score will be made available publicly via an interface that will perform all calculations for the individual.

Normalisation of CD4 counts in patients with HIV-1 infection and maximum virological suppression who are taking combination antiretroviral therapy: an observational cohort study

BACKGROUND

Combination antiretroviral therapy (cART) has been shown to reduce mortality and morbidity in patients with HIV. As viral replication falls, the CD4 count increases, but whether the CD4 count returns to the level seen in HIV-negative people is unknown. We aimed to assess whether the CD4 count for patients with maximum virological suppression (viral load <50 copies per mL) continues to increase with long-term cART to reach levels seen in HIV-negative populations.

METHODS

We compared increases in CD4 counts in 1835 antiretroviral-naive patients who started cART from EuroSIDA, a pan-European observational cohort study. Rate of increase in CD4 count (per year) occurring between pairs of consecutive viral loads below 50 copies per mL was estimated using generalised linear models, accounting for multiple measurements for individual patients.

FINDINGS

The median CD4 count at starting cART was 204 cells per microL (IQR 85-330). The greatest mean yearly increase in CD4 count of 100 cells per microL was seen in the year after starting cART. Significant, but lower, yearly increases in CD4 count, around 50 cells per microL, were seen even at 5 years after starting cART in patients whose current CD4 count was less than 500 cells per microL. The only groups without significant increases in CD4 count were those where cART had been taken for more than 5 years with a current CD4 count of more than 500 cells per microL, (current mean CD4 count 774 cells per microL; 95% CI 764-783). Patients starting cART with low CD4 counts (<200 cells per microL) had significant rises in CD4 counts even after 5 years of cART.

INTERPRETATION

Normalisation of CD4 counts in HIV-infected patients for all infected individuals might be achievable if viral suppression with cART can be maintained for a sufficiently long period of time.

A coronary heart disease risk model for predicting the effect of potent antiretroviral therapy in HIV-1 infected men

BACKGROUND

Many HIV-infected patients on highly active antiretroviral therapy (HAART) experience metabolic complications including dyslipidaemia and insulin resistance, which may increase their coronary heart disease (CHD) risk. We developed a prognostic model for CHD tailored to the changes in risk factors observed in patients starting HAART.

METHODS

Data from five cohort studies (British Regional Heart Study, Caerphilly and Speedwell Studies, Framingham Offspring Study, Whitehall II) on 13,100 men aged 40-70 and 114,443 years of follow up were used. CHD was defined as myocardial infarction or death from CHD. Model fit was assessed using the Akaike Information Criterion; generalizability across cohorts was examined using internal-external cross-validation.

RESULTS

A parametric model based on the Gompertz distribution generalized best. Variables included in the model were systolic blood pressure, total cholesterol, high-density lipoprotein cholesterol, triglyceride, glucose, diabetes mellitus, body mass index and smoking status. Compared with patients not on HAART, the estimated CHD hazard ratio (HR) for patients on HAART was 1.46 (95% CI 1.15-1.86) for moderate and 2.48 (95% CI 1.76-3.51) for severe metabolic complications.

CONCLUSIONS

The change in the risk of CHD in HIV-infected men starting HAART can be estimated based on typical changes in risk factors, assuming that HRs estimated using data from non-infected men are applicable to HIV-infected men. Based on this model the risk of CHD is likely to increase, but increases may often be modest, and could be offset by lifestyle changes.

Chronic renal failure among HIV-1-infected patients

BACKGROUND

The role of exposure to antiretrovirals in chronic renal failure (CRF) is not well understood. Glomerular filtration rates (GFR) are estimated using the Cockcroft-Gault (CG) or Modification of Diet in Renal Disease (MDRD) equations.

METHODS

Baseline was arbitrarily defined as the first recorded GFR; patients with two consecutive GFR < or = 60 ml/min per 1.73 m(2) were defined as having CRF. Logistic regression was used to determine odds ratio (OR) of CRF at baseline. ART exposure (yes/no or cumulative exposure) prior to baseline was included in multivariate models (adjusted for region of Europe, age, prior AIDS, CD4 cell count nadir, viral load, hypertension and use of nephrotoxic anti-infective therapy).

RESULTS

Using CG, the median GFR at baseline (n = 4474) was 94.4 (interquartile range, 80.5-109.3); 158 patients (3.5%) had CRF. Patients with CRF were older (median, 61.9 versus 43.1 years), had lower CD4 cell count nadirs (median, 80 versus 137 cells/microl), and were more likely to be diagnosed with AIDS (44.3 versus 30.4%), diabetes (16.5 versus 4.3%) or hypertension (53.8 versus 26.4%), all P < 0.001. In a multivariate model any use of indinavir [odds ratio (OR) 2.49; 95% confidence interval (CI), 1.62-3.83] or tenofovir (OR, 2.18; 95% CI, 1.25-3.81) was associated with increased odds of CRF, as was cumulative exposure to indinavir (OR, 1.15 per year of exposure; 95% CI, 1.06-1.25) or tenofovir (OR, 1.60; 95% CI, 1.20-2.15). Highly consistent results were seen using the MDRD formula.

CONCLUSIONS

Among antiretrovirals, only exposure to indinavir or tenofovir was associated with increased odds of CRF. We used a confirmed low GFR to define CRF to increase the robustness of our analysis, although there are several potential biases associated with this cross-sectional analysis.

Class of antiretroviral drugs and the risk of myocardial infarction

BACKGROUND

We have previously demonstrated an association between combination antiretroviral therapy and the risk of myocardial infarction. It is not clear whether this association differs according to the class of antiretroviral drugs. We conducted a study to investigate the association of cumulative exposure to protease inhibitors and nonnucleoside reverse-transcriptase inhibitors with the risk of myocardial infarction.

METHODS

We analyzed data collected through February 2005 from our prospective observational study of 23,437 patients infected with the human immunodeficiency virus. The incidence rates of myocardial infarction during the follow-up period were calculated, and the associations between myocardial infarction and exposure to protease inhibitors or nonnucleoside reverse-transcriptase inhibitors were determined.

RESULTS

Three hundred forty-five patients had a myocardial infarction during 94,469 person-years of observation. The incidence of myocardial infarction increased from 1.53 per 1000 person-years in those not exposed to protease inhibitors to 6.01 per 1000 person-years in those exposed to protease inhibitors for more than 6 years. After adjustment for exposure to the other drug class and established cardiovascular risk factors (excluding lipid levels), the relative rate of myocardial infarction per year of protease-inhibitor exposure was 1.16 (95% confidence interval [CI], 1.10 to 1.23), whereas the relative rate per year of exposure to nonnucleoside reverse-transcriptase inhibitors was 1.05 (95% CI, 0.98 to 1.13). Adjustment for serum lipid levels further reduced the effect of exposure to each drug class to 1.10 (95% CI, 1.04 to 1.18) and 1.00 (95% CI, 0.93 to 1.09), respectively.

CONCLUSIONS

Increased exposure to protease inhibitors is associated with an increased risk of myocardial infarction, which is partly explained by dyslipidemia. We found no evidence of such an association for nonnucleoside reverse-transcriptase inhibitors; however, the number of person-years of observation for exposure to this class of drug was less than that for exposure to protease inhibitors.

Primary pneumocystis infection in infants hospitalized with acute respiratory tract infection

Acquisition of Pneumocystis jirovecii infection early in life has been confirmed by serologic studies. However, no evidence of clinical illness correlated with the primary infection has been found in immunocompetent children. We analyzed 458 nasopharyngeal aspirates from 422 patients hospitalized with 431 episodes of acute respiratory tract infection (RTI) by using a real-time PCR assay. In 68 episodes in 67 infants, P. jirovecii was identified. The odds ratio (95% confidence interval) of a positive signal compared with the first quartile of age (7-49 days) was 47.4 (11.0-203), 8.7 (1.9-39.7), and 0.6 (0.1-6.7) for infants in the second (50-112 days), third (113-265 days), and fourth (268-4,430 days) age quartiles, respectively. Infants with an episode of upper RTI (URTI) were 2.0 (1.05-3.82) times more likely to harbor P. jirovecii than infants with a lower RTI. P. jirovecii may manifest itself as a self-limiting URTI in infants, predominantly those 1.5-4 months of age.

Risk of Discontinuation of Nevirapine due to Toxicities in Antiretroviral-Naive and -Experienced HIV-Infected patients with High and Low CD4+ T-cell Counts

Introduction

It is unknown whether the increased risk of toxicities in antiretroviral-naive HIV-infected patients initiating nevirapine-based (NVPc) combination antiretroviral therapy (cART) with high CD4+ T-cell counts is also observed when NVPc is initiated in cART-experienced patients.

Patients and methods

1,571 EuroSIDA patients started NVPc after 1/1/1999, with CD4+ T-cell counts and viral load measured in the 6 months before starting treatment, and were stratified into four groups based on CD4+ T-cell counts at initiation of NVPc (high [H], >400/mm3 or >250/mm3 for male or female, respectively, or low [L], ≤400/mm3 or ≤250/mm3 for male or female) and prior antiretroviral experience (antiretroviral-naive [N] or -experienced [E]). Cox proportional hazards models compared the risks of discontinuation of nevirapine due to toxicities or patient/physician choice (TOXPC).

Results

After adjustment, there was a significantly lower risk of discontinuation of nevirapine due to TOXPC in the HE group ( n=588; proportion discontinued by 3/12 months: 10/17%, respectively) than in HN (n=62; 21/32% respectively; overall relative hazard [RH]: 0.56; 95% confidence interval [CI]: 0.34–0.94; P=0.027). This difference was most pronounced during the first 3 months of NVPc (RH: 0.44; 95% CI: 0.23–0.87; P=0.017). There were no deaths in the 6 months after starting NVPc resulting from exposure to <3 months of NVPc exposure within the HE group (incidence: 0; per 1,000 person-years follow up; 95% CI: 0–6.9). After adjustment, there were no differences between the HE and HN groups in discontinuation due to TOXPC in patients starting efavirenz-based cART (RH: 0.91; 95% CI: 0.60–1.38; P=0.66) or protease-inhibitor-based cART (RH: 1.13; 95% CI: 0.77–1.66; P=0.52).

Conclusions

Results from this non-randomized study suggest that NVPc might be safer to initiate in antiretro-viral-experienced than in antiretroviral-naive patients with high CD4+T-cell counts.

Evolution of drug resistance in HIV-infected patients remaining on a virologically failing combination antiretroviral therapy regimen

OBJECTIVE

To estimate the extent of drug resistance accumulation in patients kept on a virologically failing regimen and its determinants in the clinical setting.

DESIGN

The study focused on 110 patients of EuroSIDA on an unchanged regimen who had two genotypic tests performed at two time points (t0 and t1) when viral load was > 400 copies/ml.

METHODS

Accumulation of resistance between t0 and t1 was measured using genotypic susceptibility scores (GSS) obtained by counting the total number of active drugs (according to the Rega system v6.4.1) among all licensed antiretrovirals as of 1 January 2006. Patients were grouped according to the number of active drugs in the failing regimen at t0 (GSS_f-t0).

RESULTS

At t0, patients had been on the failing combination antiretroviral therapy (cART) for a median of 11 months (range, 6-50 months). Even patients with extensive resistance to the failing regimen were still receiving benefit from treatment. An overall 6-monthly increase of 1.96 (SD, 2.23) International Aids Society-mutations and an average loss of 1.25 (SD, 1.81) active drugs were estimated. In comparison with patients with GSS_f-t0 = 0, the number of active drugs lost was -1.08 [95% confidence interval (CI), -2.13 to -0.03; P = 0.04] in those with GSS_f-t0 of 0.5-1.5 and -1.24 (95% CI, -2.44 to -0.04; P = 0.04) in those with GSS_f-t0 >or= 2.

CONCLUSIONS

In patients kept on the same virologically failing cART regimen for a median of 6 months, there was considerable accumulation of drug resistance mutations, particularly in patients with initial low level of resistance to the failing regimen. Randomized comparisons of maintenance treatment strategies while awaiting a new suppressive therapy to become available are warranted.

Interruption of combination antiretroviral therapy and risk of clinical disease progression to AIDS or death

OBJECTIVES

The aim of the study was to compare incidence rates (IRs) of AIDS/death in patients with and without treatment interruption (TI) of combination antiretroviral therapy (cART) for periods of 3 months or more for different categories of CD4 cell count and viral load, and to determine risk factors for clinical progression to AIDS/death.

METHODS

Patients starting cART with a CD4 cell count and a viral load available within 6 months of starting cART were included in the study. The IR and risk factors of TI were determined. We assessed the incidence rate ratios (IRRs) for TI and AIDS/death events using Poisson regression models.

RESULTS

Of 3811 patients included in the study, 26% were ART-naïve prior to cART. The median date of starting cART was July 1997, the median CD4 cell count was 226 cells/microL and the median viral load was 4.36 log(10) HIV-1 RNA copies/mL. We observed 1243 interruptions and 403 AIDS-events/deaths. The IR of AIDS/death was higher in patients with lower CD4 cell counts or higher viral loads, regardless of TI. After adjusting for baseline factors, the IR of AIDS/death was significantly higher in the TI group than in the non-TI group [IRR 2.63; 95% confidence interval (CI) 2.01-3.44; P<0.0001]; this could be explained by current CD4 cell counts and viral loads, as the CD4 cell count- and viral load-adjusted IRR was 1.14 (95% CI 0.86-1.51; P=0.37). Within the TI group, patients with a current CD4 cell count of <200 cells/microL had a 3-fold higher risk of AIDS/death than those with a CD4 cell count of 200-350 cells/microL, whereas patients with a current CD4 cell count of >350 cells/microL had a 4-fold lower risk of disease progression.

CONCLUSIONS

TI is common in clinical practice. The risk of AIDS/death increased more than 2-fold for patients stopping all cART regimen drugs for 3 months or more. Among patients experiencing a TI, those with low CD4 cell counts, high viral loads or prior AIDS had an increased risk of AIDS/death. Hence, TI should be discouraged and closely monitored if it occurs.