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Biomedical subjects

Rodolphe Thiébaut

Publications and source records attributed to Rodolphe Thiébaut.

At least 19 recordsLinked to original sources
PubMed2007

Effectiveness of prenatal treatment for congenital toxoplasmosis: a meta-analysis of individual patients' data.

BACKGROUND: Despite three decades of prenatal screening for congenital toxoplasmosis in some European countries, uncertainty remains about the effectiveness of prenatal treatment. METHODS: We did a systematic review of cohort studies based on universal screening for congenital toxoplasmosis. We did a meta-analysis using individual patients' data to assess the effect of timing and type of prenatal treatment on mother-to-child transmission of infection and clinical manifestations before age 1 year. Analyses were adjusted for gestational age at maternal seroconversion and other covariates. FINDINGS: We included 26 cohorts in the review. In 1438 treated mothers identified by prenatal screening, we found weak evidence that treatment started within 3 weeks of seroconversion reduced mother-to-child transmission compared with treatment started after 8 or more weeks (adjusted odds ratio [OR] 0.48, 95% CI 0.28-0.80; p=0.05). In 550 infected liveborn infants identified by prenatal or neonatal screening, we found no evidence that prenatal treatment significantly reduced the risk of clinical manifestations (adjusted OR for treated vs not treated 1.11, 95% CI 0.61-2.02). Increasing gestational age at seroconversion was strongly associated with increased risk of mother-to-child transmission (OR 1.15, 95% CI 1.12-1.17) and decreased risk of intracranial lesions (0.91, 0.87-0.95), but not with eye lesions (0.97, 0.93-1.00). INTERPRETATION: We found weak evidence for an association between early treatment and reduced risk of congenital toxoplasmosis. Further evidence from observational studies is unlikely to change these results and would not distinguish whether the association is due to treatment or to biases caused by confounding. Only a large randomised controlled clinical trial would provide clinicians and patients with valid evidence of the potential benefit of prenatal treatment.

Coccidiostats↗
PubMed2006

Decrease in circulating dendritic cells predicts fatal outcome in septic shock.

OBJECTIVE: Biomarkers allowing accurate early staging of septic shock patients are lacking despite their obvious interest for patient management. Experimental models of septic shock in mouse previously noted a decrease in dendritic cell numbers. The aim of the study was to find a rapid reproducible biological test for an assessment of disease severity. DESIGN: Evaluation of peripheral blood dendritic cell counts by flow cytometry using three commercially available kits. PATIENTS AND PARTICIPANTS: Forty-two consecutive septic shock patients were studied prospectively. MEASUREMENTS AND RESULTS: Early low dendritic cell counts were correlated to disease severity as assessed by Simplified Acute Physiology Score or Sequential Organ Failure Assessment and predicted fatal outcome. The correlation was still present when the results were adjusted for age. CONCLUSION: The monitoring of blood dendritic cell count may provide an early and valuable assessment of the severity of the host response against infection and may influence the therapeutic management of septic shock patients.

Adult↗
PubMed2006

Estimation of dynamical model parameters taking into account undetectable marker values.

BACKGROUND: Mathematical models are widely used for studying the dynamic of infectious agents such as hepatitis C virus (HCV). Most often, model parameters are estimated using standard least-square procedures for each individual. Hierarchical models have been proposed in such applications. However, another issue is the left-censoring (undetectable values) of plasma viral load due to the lack of sensitivity of assays used for quantification. A method is proposed to take into account left-censored values for estimating parameters of non linear mixed models and its impact is demonstrated through a simulation study and an actual clinical trial of anti-HCV drugs. METHODS: The method consists in a full likelihood approach distinguishing the contribution of observed and left-censored measurements assuming a lognormal distribution of the outcome. Parameters of analytical solution of system of differential equations taking into account left-censoring are estimated using standard software. RESULTS: A simulation study with only 14% of measurements being left-censored showed that model parameters were largely biased (from -55% to +133% according to the parameter) with the exception of the estimate of initial outcome value when left-censored viral load values are replaced by the value of the threshold. When left-censoring was taken into account, the relative bias on fixed effects was equal or less than 2%. Then, parameters were estimated using the 100 measurements of HCV RNA available (with 12% of left-censored values) during the first 4 weeks following treatment initiation in the 17 patients included in the trial. Differences between estimates according to the method used were clinically significant, particularly on the death rate of infected cells. With the crude approach the estimate was 0.13 day-1 (95% confidence interval [CI]: 0.11; 0.17) compared to 0.19 day-1 (CI: 0.14; 0.26) when taking into account left-censoring. The relative differences between estimates of individual treatment efficacy according to the method used varied from 0.001% to 37%. CONCLUSION: We proposed a method that gives unbiased estimates if the assumed distribution is correct (e.g. lognormal) and that is easy to use with standard software.

AIDS-Related Opportunistic Infections↗
PubMed2006

Virological response to HIV-1 nucleoside/nucleotide reverse transcriptase inhibitors-based, tenofovir DF-including regimens in the ANRS Aquitaine Cohort.

BACKGROUND: HIV-1 nucleoside/tide reverse transcriptase inhibitors (NRTI)-only based, comprising tenofovir DF(TDF) have been shown to lead to high rates of virological failures (VF), mainly in patients on first-line combination therapy. We wished to investigate the virological response to these regimens in a large cohort of antiretroviral (ARV)-treated patients. METHODS: Patients followed-up in the Aquitaine Cohort in 2001-2003 and who had received NRTI-based, TDF-including regimens for at least 3 months were included. The VF was defined as: (i) a decrease in plasma HIV-1 RNA <0.5 log(10)copies/ml between M0 and M3; or (ii) a plasma HIV-1 RNA >50 copies/ml at M3 in patients with plasma HIV-1 RNA <50 copies/ml at M0. The baseline RT genotype was determined in a subgroup of patients. RESULTS: Within 121 patients (95% ARV-experienced) who received either lamivudine (3TC)/didanosine (DDI)/TDF (n=48), or abacavir (ABC)/3TC/TDF (n=14), or 3TC/zidovudine (ZDV)/TDF (n=27), or 3TC/ZDV/ABC/TDF (n=20), or DDI/ABC/TDF (n=12), the ABC/3TC/TDF and DDI/ABC/TDF combinations were associated with the highest frequencies of VF. In contrast the use of ZDV was related to a better virological response. The baseline RT genotype was also predictive of the virological outcome. CONCLUSION: NRTI-based, TDF-including therapies can lead to high rates of VF both in ARV-naïve and in ARV-experienced patients. Our data strongly suggest the interest of associating ZDV and TDF in these regimens.

Adenine↗
PubMed2006

Behavioral audiometry: validity of audiometric measurements obtained using the "Delaroche protocol" in babies aged 4--18 months suffering from bilateral sensorineural hearing loss.

OBJECTIVE: Evaluation of the validity of the audiometric measurements obtained in babies aged from 4 to 18 months suffering from bilateral sensorineural hearing loss (SNHL) using an original behavioral audiometry (BA) protocol called the "Delaroche protocol" [IJPORL 68 (2004) 1233-1243]. METHODS: (1) We compared the auditory brainstem (ABR) threshold in the better ear with the mean of the BA thresholds obtained, bilaterally, at 2000 and 4000 Hz, both measurements being performed in the diagnostic phase. (2) We compared the BA thresholds obtained prior to the age of 18 months, bilaterally, at the frequencies of 500,1000, 2000 and 4000 Hz, with the thresholds of the better ear obtained at the same frequencies at the age of 3--4 years by BA. RESULTS: (1) Cross- sectional study (78 children). When there was no ABR at 100 db, there was no BA response at 100 dB in 84.2% of cases, resulting in a kappa coefficient of 0.72. When there were ABR, the difference between the ABR and the BA thresholds was equal to or less than 10 dB in 67% of cases and equal to or less than 20 dB in 95% of cases. (2) Longitudinal study (50 children). The difference between the behavioral thresholds obtained within 4 and 18 months (median age=12 months) and those obtained at 3 or 4 years old in the same children (median age=39 months) was equal to or less than 10 dB in 94% of cases at the frequencies of 1000, 2000 and 4000 Hz and in 78% of cases at 500 Hz. CONCLUSION: The two analysis evidence the validity of the behavioral measurements obtained at an early age using the protocol described.

Acoustic Impedance Tests↗
PubMed2006

Change in T-lymphocyte count after initiation of highly active antiretroviral therapy in HIV-infected patients with history of Mycobacterium avium complex infection.

OBJECTIVE: To compare changes in CD4+, CD8+ and total lymphocyte counts after initiation of highly active antiretroviral therapy (HAART) between HIV-infected patients with and without a recent history of Mycobacterium avium complex (MAC) infection. METHOD: Matched exposed-non-exposed retrospective cohort study. RESULTS: Fifty-one patients with a recent history of MAC infection (MAC+) started a combination of at least three antiretroviral drugs. They were individually matched to 145 patients without any history of MAC infection (MAC-) according to CD4+ T-cell count (+/- 30 cells/mm3), previous experience of antiretroviral treatment, AIDS clinical stage at the time of HAART initiation (baseline), age (+/- 10 years) and gender. MAC+ and MAC- patients presented comparable median levels of total lymphocytes (488 vs 688/mm3, P=0.09), CD4+ (11 vs 16/mm3, P=0.15), CD8+ count (359 vs 386/mm3, P=0.39) and plasma HIV RNA (5.3 vs 5.1 log10 copies/ml, P=0.22) at baseline. After 6 months on HAART, the median increase of CD4+ T-cell count was 28 cells/mm3 (interquartile range [IQR]: 1-63) in MAC+ and 72 cells/mm3 (IQR: 34-120) in MAC- patients (P<0.0001), whereas the percentage of CD4+ T cells was not significantly different between the two groups (P=0.13). Comparable differences were observed for total lymphocytes and CD8+ T cells (P<0.001). The 6 months decline of plasma HIV RNA was not significantly different according to MAC exposure (-1.6 in MAC+ vs -1.8 log10 copies/ml in MAC- patients, P=0.65). Results were confirmed after adjustment for other characteristics than the matching variables and after taking into account potential informative bias due to unbalanced number of deaths between the two groups. CONCLUSION: MAC infection at the time of HAART initiation is an important deleterious factor for immune reconstitution. A better understanding of the underlying mechanism and an evaluation of additional treatment strategies are necessary to help immune restoration in such circumstances.

AIDS-Related Opportunistic Infections↗
PubMed2005

Factors associated with the occurrence of AIDS-related non-Hodgkin lymphoma in the era of highly active antiretroviral therapy: Aquitaine Cohort, France.

BACKGROUND: High grade non-Hodgkin lymphoma (NHL) remains the most common Acquired Immune Deficiency Syndrome (AIDS)-associated neoplasia and an important cause of mortality in people living with human immunodeficiency virus (HIV) infection in industrialized countries in the era of highly active antiretroviral therapy (HAART). METHOD: A case-control study was implemented in a large cohort of HIV-infected patients. Case patients had newly diagnosed NHL, and control subjects were matched for CD4(+) cell count, calendar period, sex, and length of follow-up. RESULTS: Variables associated with a decreased risk of NHL were the use of HAART during follow-up for at least 6 months (odds ratio [OR], 0.46; 95% confidence interval [CI], 0.21-0.98), receipt of a diagnosis of AIDS before the censoring date (OR, 0.37; 95% CI, 0.18-0.76), and undetectable level of HIV RNA during follow-up (OR, 0.34; 95% CI, 0.15-0.77). The use of antiherpetic drug for at least 6 months was associated with a nonsignificant decreased risk of NHL (OR, 0.40; 95% CI, 0.11-1.44; P=.16). In multivariate analysis, variables significantly associated with a decreased risk of NHL were the use of HAART for at least 6 months during follow-up (OR, 0.37; 95% CI, 0.16-0.87) and receipt of an AIDS-related diagnosis before the censoring date (OR, 0.44; 95% CI, 0.21-0.93). Age, transmission group, hepatitis B and C coinfections, CD4(+) and CD8(+) cell count nadir, and previous history of herpes virus infection were not associated with an increased risk for NHL. CONCLUSION: The use of HAART for at least 6 months was associated with a decreased risk of NHL, whereas uncontrolled HIV RNA load may be associated with an increased risk. The role of antiherpetic drugs needs further investigation.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Biases in observational studies of the effect of prenatal treatment for congenital toxoplasmosis.

The paper reviews methodological difficulties that arise when using observational studies to evaluate the effect of prenatal screening and treatment. The principle of each difficulty is described and then illustrated by a clinical example of toxoplasmosis in pregnancy and its consequences. Methods to deal with these difficulties are described. Given the limitations of existing observational studies and lack of randomised controlled trials, a systematic review of cohort studies offers the best approach for exploring potential biases.

Adult↗
PubMed2005

Change in atherosclerosis progression in HIV-infected patients: ANRS Aquitaine Cohort, 1999-2004.

This study reported the changes in carotid intima-media thickness (IMT) during a 36-month period in 233 HIV-infected patients. Median IMT increased in the first 12 months and then decreased by month 36. The prevalence of treatment with lipid-lowering agents and protease inhibitor-free highly active antiretroviral therapy regimens increased, whereas smoking prevalence decreased. The progression of atherosclerosis in HIV-infected patients can be controlled. The impact of individual measures to reduce the cardiovascular risk should be evaluated further.

Adult↗
PubMed2005

Joint modelling of bivariate longitudinal data with informative dropout and left-censoring, with application to the evolution of CD4+ cell count and HIV RNA viral load in response to treatment of HIV infection.

Several methodological issues occur in the context of the longitudinal study of HIV markers evolution. Three of them are of particular importance: (i) correlation between CD4+ T lymphocytes (CD4+) and plasma HIV RNA; (ii) left-censoring of HIV RNA due to a lower quantification limit; (iii) and potential informative dropout. We propose a likelihood inference for a parametric joint model including a bivariate linear mixed model for the two markers and a lognormal survival model for the time to drop out. We apply the model to data from patients starting antiretroviral treatment in the CASCADE collaboration where all of the three issues needed to be addressed.

Anti-HIV Agents↗
PubMed2005

Immunological markers after long-term treatment interruption in chronically HIV-1 infected patients with CD4 cell count above 400 x 10(6) cells/l.

OBJECTIVE: To analyse immunological markers associated with CD4+ lymphocyte T-cell count (CD4+) evolution during 12-month follow-up after treatment discontinuation. METHOD: Prospective observational study of chronically HIV-1 infected patients with CD4+ above 400 x 10(6) cells/l. RESULTS: CD4+ changes took place in two phases: an initial rapid decrease in the first month (-142 x 10(6) cells/l on average), followed by a slow decline (-17 x 10(6) cells/l on average) The second slope of CD4+ decline was not correlated with the first and only baseline plasma HIV RNA was associated with it. The decline in CD4+ during the first month was steeper in patients with higher CD4+ and weaker plasma HIV RNA baseline levels. Moreover, the decline was less pronounced (P < 10(-4)) in patients with CD4+ nadir above 350 x 10(6) cells/l (-65 x 10(6) cells/l per month) in comparison with those below 350 x 10(6) cells/l (-200 x 10(6) cells/l per month). A high number of dendritic cells (DCs) whatever the type was associated with high CD4+ at the time of treatment interruption and its steeper decline over the first month. Moreover, the myeloid DC level was stable whereas the lymphoid DC count, which tended to decrease in association with decrease in CD4+, was negatively correlated with the HIV RNA load slope. CONCLUSIONS: The results support the use of the CD4+ nadir to predict the CD4+ dynamic after treatment interruption and consideration of the CD4+ count after 1-month of interruption merely reflects the 12-month level of CD4+. Although DCs seem to be associated with the CD4+ dynamic, the benefit of monitoring them has still to be defined.

Adult↗
PubMed2005

Can highly active antiretroviral therapy be interrupted in patients with sustained moderate HIV RNA and > 400 CD4+ cells/microl? Impact on immunovirological parameters.

Because the effects of treatment interruption on patients with >400 CD4(+) cells/microl and prolonged moderate HIV loads is unknown, their HIV1 RNA and DNA loads, plasma, and PBMC resistance mutations and CD4+ kinetics were studied during 12 months of treatment interruption. Fifty-seven patients were included: 28 with undetectable (median 40 months) and 29 with moderate (>1 year) HIV1 RNA levels (3.3 log10 copies/ml) at the baseline M0. HIV1 RNA and CD4+ counts were determined monthly. PBMC HIV1 DNA was quantified (real-time PCR) and its reverse transcriptase (RT) and protease (PR) genotypes analyzed (M0, M6, M12). Regardless of HIV1 RNA detectability at the baseline M0, all patients had comparable HIV1 RNA (median 4.6), DNA (median 2.9), CD4+ (median 455) at month 12 (M12). The decisive moment was month 1 (M1), when the HIV1 RNA increase and CD4 decline stabilized, rendering M0 differences non-significant and predicting outcome. The lower the CD4+ nadir was before HAART, the steeper the CD4+ decline at M1. HIV1 DNA shifted to wild-type genotype in 47% (M6) and 79% (M12) of RT; 64% of PR major resistance mutations disappeared (M12). Treatment interruption is possible, regardless of the baseline M0 HIV RNA status, but it must take into consideration the CD4+ nadir, an outcome predictor, to initiate HAART before too severe depletion to preserve the possibility of treatment interruption. HIV1 DNA genotyping helps monitor patients with undetectable HIV RNA at M0.

Anti-HIV Agents↗
PubMed2005

Counterfactual links to the proportion of treatment effect explained by a surrogate marker.

In a randomized clinical trial, a statistic that measures the proportion of treatment effect on the primary clinical outcome that is explained by the treatment effect on a surrogate outcome is a useful concept. We investigate whether a statistic proposed to estimate this proportion can be given a causal interpretation as defined by models of counterfactual variables. For the situation of binary surrogate and outcome variables, two counterfactual models are considered, both of which include the concept of the proportion of the treatment effect, which acts through the surrogate. In general, the statistic does not equal either of the two proportions from the counterfactual models, and can be substantially different. Conditions are given for which the statistic does equal the counterfactual model proportions. A randomized clinical trial with potential surrogate endpoints is undertaken in a scientific context; this context will naturally place constraints on the parameters of the counterfactual model. We conducted a simulation experiment to investigate what impact these constraints had on the relationship between the proportion explained (PE) statistic and the counterfactual model proportions. We found that observable constraints had very little impact on the agreement between the statistic and the counterfactual model proportions, whereas unobservable constraints could lead to more agreement.

Anti-HIV Agents↗
PubMed2005

Predictors of hypertension and changes of blood pressure in HIV-infected patients.

OBJECTIVE: We assessed predictors of changes in systolic (SBP) and diastolic (DBP) blood pressure during follow-up and of the development of hypertension in HIV-infected individuals. METHODS: International cohort collaborative study (D:A:D) of established prospective cohorts of HIV-1-infected patients. Longitudinal analysis of changes in blood pressure (BP) was performed using mixed effects models in 17170 patients. Predictors of development of hypertension during follow-up (systolic BP > or =140 and/or diastolic BP > or =90 mmHg or initiation of antihypertensive treatment) were assessed using Cox models in 8 984 patients with a normal BP level at baseline. RESULTS: 73548 BP measurements with a median of 4 per patient (interquartile range [IQR]: 2-6) were recorded over a median follow-up of 2.3 years (IQR: 1.5-2.6). Risk factors significantly associated with a development of higher systolic BP and diastolic BP (differences > or =5 mmHg and P-values <0.001) during follow-up were: older age, male sex, higher body mass index (BMI) and use of BP-lowering drugs. In patients with normal BP at baseline, 1186 developed hypertension for an incidence of 72.1 per 1000 person-years (95% confidence interval: 68.2-76.0). Factors associated with development of hypertension were: male sex, higher BMI, older age, higher BP at baseline, high total cholesterol and clinical lipodystrophy. Cumulative duration of exposure to nucleoside reverse transcriptase inhibitors (P=0.75), protease inhibitors (P=0.92) as well as type of antiretroviral treatment at baseline (P=0.18) were not associated with a higher risk of hypertension. Cumulative duration of exposure to non-nucleoside reverse transcriptase inhibitors (NNRTIs) was significantly associated with lower risk of hypertension (hazard ratio=0.78 and 0.67 for those treated < or =10 months and >10 months compared with no exposure; P=0.005). CONCLUSIONS: Increased blood pressure in HIV-infected individuals is associated with established risk factors for hypertension. There was no evidence for an independent deleterious effect of any class of antiretroviral drugs on BP, although the use of NNRTIs was associated with a lower risk of development of hypertension.

Adult↗
PubMed2005

Treatment of dyslipidaemia in HIV-infected persons.

Accumulating evidence suggests that HIV-infected individuals have an increased risk of cardiovascular events. This risk seems to be at least partially mediated by dyslipidaemia, which is related to the use of highly active antiretroviral therapy (HAART). As HIV-infected individuals live longer due to HAART, their cardiovascular risk will invariably increase. Because HAART is likely to be used indefinitely, HAART-related dyslipidaemia has emerged as a major cardiovascular concern. This article summarises the evaluation of dyslipidaemia and cardiovascular risk in HIV-infected individuals, the potential pathophysiological and genetic mechanisms involved in HAART-related dyslipidaemia and the current treatment approaches. In general, dyslipidaemia is evaluated and treated as in HIV-negative persons. The first step is cardiovascular risk assessment and the determination of target lipid levels. A healthier lifestyle and, in particular, smoking cessation should be promoted. Lowering levels of low-density lipoprotein cholesterol (or, in the setting of significant hypertriglyceridaemia, non-high-density lipoprotein cholesterol) is the primary target of intervention. Switching HAART to a more lipid-favourable regimen should be considered if this does not jeopardise virological control. Many patients will need lipid-lowering drug therapy. Appropriate low-density lipoprotein cholesterol target levels may be more difficult to reach than in the HIV-negative population, and the potential for drug interactions when using lipid-lowering agents together with HAART needs to be considered. The identification of HAART strategies with no or minimal metabolic toxicity, and the identification of the safest and most efficacious lipid-lowering therapies for HIV-infected individuals with dyslipidaemia are important research goals.

Antiretroviral Therapy, Highly Active↗
PubMed2004

Mixed models for longitudinal left-censored repeated measures.

Longitudinal studies could be complicated by left-censored repeated measures. For example, in Human Immunodeficiency Virus infection, there is a detection limit of the assay used to quantify the plasma viral load. Simple imputation of the limit of the detection or of half of this limit for left-censored measures biases estimations and their standard errors. In this paper, we review two likelihood-based methods proposed to handle left-censoring of the outcome in linear mixed model. We show how to fit these models using SAS Proc NLMIXED and we compare this tool with other programs. Indications and limitations of the programs are discussed and an example in the field of HIV infection is shown.

HIV Infections↗
PubMed2003

Combination antiretroviral therapy and the risk of myocardial infarction.

BACKGROUND: It remains controversial whether exposure to combination antiretroviral treatment increases the risk of myocardial infarction. METHODS: In this prospective observational study, we enrolled 23,468 patients from 11 previously established cohorts from December 1999 to April 2001 and collected follow-up data until February 2002. Data were collected on infection with the human immunodeficiency virus and on risk factors for and the incidence of myocardial infarction. Relative rates were calculated with Poisson regression models. Combination antiretroviral therapy was defined as any combination regimen of antiretroviral drugs that included a protease inhibitor or a nonnucleoside reverse transcriptase inhibitor. RESULTS: Over a period of 36,199 person-years, 126 patients had a myocardial infarction. The incidence of myocardial infarction increased with longer exposure to combination antiretroviral therapy (adjusted relative rate per year of exposure, 1.26 [95 percent confidence interval, 1.12 to 1.41]; P<0.001). Other factors significantly associated with myocardial infarction were older age, current or former smoking, previous cardiovascular disease, and male sex, but not a family history of coronary heart disease. A higher total serum cholesterol level, a higher triglyceride level, and the presence of diabetes were also associated with an increased incidence of myocardial infarction. CONCLUSIONS: Combination antiretroviral therapy was independently associated with a 26 percent relative increase in the rate of myocardial infarction per year of exposure during the first four to six years of use. However, the absolute risk of myocardial infarction was low and must be balanced against the marked benefits from antiretroviral treatment.

Adult↗