[Show abstract][Hide abstract] ABSTRACT: Estimations of survival rates are diverse and the choice of the appropriate method depends on the context. Given the increasing interest in multiple imputation methods, we explored the interest of a multiple imputation approach in the estimation of cause-specific survival, when a subset of causes of death was observed.
By using European Randomized Study of Screening for Prostate Cancer (ERSPC), 20 multiply imputed datasets were created and analyzed with a Multivariate Imputation by Chained Equation (MICE) algorithm. Then, cause-specific survival was estimated on each dataset with two methods: Kaplan-Meier and competing risks. The two pooled cause-specific survival and confidence intervals were obtained using Rubin's rules after complementary log-log transformation. Net survival was estimated using Pohar-Perme's estimator and was compared to pooled cause-specific survival. Finally, a sensitivity analysis was performed to test the robustness of our constructed multiple imputation model.
Cause-specific survival performed better than net survival, since this latter exceeded 100 % for almost the first 2 years of follow-up and after 9 years whereas the cause-specific survival decreased slowly and than stabilized at around 94 % at 9 years. Sensibility study results were satisfactory.
On our basis of prostate cancer data, the results obtained by cause-specific survival after multiple imputation appeared to be better and more realistic than those obtained using net survival.
BMC Medical Research Methodology 12/2015; 15(1):54. DOI:10.1186/s12874-015-0048-4 · 2.27 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Receiver operating characteristic (ROC) research has been limited to binary choice. Recently, the method was generalized based on the Lehmann assumption also known as the proportional hazards specification. This model accommodates a variety of research questions such as covariate adjustments. By applying this method to three-class ROC analysis, simple analytical forms of ROC surface and volume under the surface were derived without and with covariates. Furthermore, the model parameters and the corresponding asymptotic variances were evaluated. Simulation studies were performed to assess the validity of our proposed method in finite samples and extension work for dimension higher than three-class is considered.
Journal of Statistical Computation and Simulation 02/2015; 85(3). DOI:10.1080/00949655.2013.831863 · 0.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This paper presents a semiparametric method for estimating receiver operating characteristic surface under density ratio model. The construction of the proposed method is based on the adjacent-category logit model and the empirical likelihood approach. A bootstrap approach for the VUS estimator inference is presented. In a simulation study, the proposed estimator is compared with the existing parametric and nonparametric estimators in terms of bias, standard error and mean square error. Finally, a real data example and some discussions on the proposed method are provided.
Communication in Statistics- Simulation and Computation 12/2014; DOI:10.1080/03610918.2013.879888 · 0.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objective:
RA is a chronic disease with frequent psychological co-morbidities, of which depression and anxiety are two common manifestations. We aimed to identify predictive factors of psychological distress in a large prospective cohort of very early RA patients.
ESPOIR (Etude et Suivi des Polyarthrites Indifférenciées Récentes) is a multicentre, longitudinal and prospective cohort study of patients with early arthritis (<6 months disease duration). The study sample comprised 641 patients with very early RA according to the 2010 ACR/European League Against Rheumatism RA criteria from the ESPOIR cohort. Psychological distress was assessed over 3 years by the five-item Mental Health Inventory questionnaire at various time points (baseline, 6, 12, 18, 24 and 36 months). Logistic regression with a generalized estimating equation model was used to analyse the association of disease variables and risk of psychological distress.
At baseline, 46.9% of RA patients were screened as positive for psychological distress. Over 3 years, psychological distress decreased significantly, with a prevalence of 25.8% at 36 months. The HAQ Disability Index (HAQ-DI) score was the most important factor predicting psychological distress over 3 years [odds ratio 2.10 (95% CI 1.41, 3.14)-3.59 (2.29, 5.63)]. Baseline biological and radiological variables and treatment regimens were not associated with distress.
Psychological distress in very early RA is frequent and the HAQ-DI score is a predictor of depression and anxiety in these patients. A psychological evaluation in patients with early RA is important for further individual psychiatric diagnosis and management.
[Show abstract][Hide abstract] ABSTRACT: Aim: The use of a CGA is recommended to detect a patient's vulnerability but its integration in treatment decision making has never been prospectively evaluated. Our main objective was to test if the use of CGA in the allocation of treatment could improve the management of advanced NSCLC in first line. Methods: Randomized, multicentric, prospective phase III study in patients ≥70 y, PS 0-2 with stage IV NSCLC. Arm A standard algorithm of chemotherapy allocation: carboplatin based doublet in PS ≤ 1 and age ≤75y, docetaxel in PS =2 or age >75y. Arm B treatment allocation based on CGA: carboplatin based doublet for fit patients, mono-therapy for vulnerable patients and BSC for frail patients. Four cycles were given every three weeks. Main endpoint: time to failure free survival (TFFS) Secondary endpoints: overall Response Rate (ORR), overall survival (OS), toxicity, QoL and life expectancy adjusted on QoL. QoL was assessed during treatment by EQ-5D health questionnaire at baseline, weeks 6, 12, 20, 28, and 36. A mixed-effects model was used, to compare the utility score and therefore the QOL between arms A and B. Results: 493 patients were randomized from 01/2010 to 01/2013 by 45 centers. Respectively in arms A and B, 34.4% and 47% of patients received a carboplatin-based doublet, 65.6% and 31.4% received docetaxel and in arm B 21.5% received BSC. Median TFFS was 3.2 m, 95%CI:[2.9; 4.1] for standard arm and 3.1 m, 95%CI:[2.7; 4.4] for experimental arm, p = 0.71. Compliance with QoL was 87% at baseline and respectively 66%, 65%, 54%, 60% and 57% at week 6, 12, 20, 28 and 36. The utility score at each evaluation is superior in the experimental arm than in the standard arm, but this difference is significant only at week 36 (p = 0.02). Using a linear mixed generalized model, the utility score tends to decrease over time and is not significantly different between the two arms (p = 0.85). Life expectancy adjusted on QoL was 130.1 days in standard arm and 133.3 days in experimental arm, p = 0.51. Conclusions: ESOGIA did not show a superiority of a CGA-based treatment allocation. In the experimental arm, more patients received a carboplatin-based doublet and 21% of frail patients received an exclusive BSC management. Despite a trend in favor of CGA arm, there is no significant difference in terms of QoL score and life expectancy adjusted on QoL. Further sudies are needed for GA in NSCLC elderly patients. Disclosure: C. Chouaid: advisory board LILLY; H. Lena: advisory board Lilly. All other authors have declared no conflicts of interest.
[Show abstract][Hide abstract] ABSTRACT: High-dose chemotherapy followed by autologous stem cell transplantation (ASCT) is a standard therapy in patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL) who are chemosensitive. The combination of carmustine, etoposide, cytarabine, and melphalan (BEAM) is commonly used as a conditioning regimen. The addition of yttrium-90 ((90) Y)-ibritumomab tiuxetan (Zevalin(®) ) to BEAM (Z-BEAM) is increasingly being used to improve outcomes and overcome refractory disease. We conducted a literature review and meta-analysis in order to evaluate the clinical effects of Z-BEAM followed by ASCT in patients with DLBCL. A literature search was conducted for randomized controlled trials and observational studies of Z-BEAM as a conditioning regimen for ASCT in adult patients with DLBCL. Extracted data included baseline patient demographics, overall response (ORR), complete response (CR), overall survival (OS), progression-free survival (PFS), nonrelapse mortality (NRM), median time to ANC and platelet engraftment, and rate of myelodysplastic syndrome. Mixed-effects models were used to determine estimates. Ten studies (N = 328) were included in the meta-analysis. The 2-year OS and PFS were 84.5% (n = 328) and 67.2% (n = 285), respectively. Outcomes were superior in patients with nontransformed lymphoma. Posttransplant, ORR and CR rates were 72.6% and 68.5%, respectively. The NRM rate was 6.3% and the incidence rate of myelodysplastic syndrome was 2.5%. Two-year OS was significantly associated with pretransplant ORR (P = 0.008, τ(2) = 0). There was no significant association between PFS and pretransplant response. Z-BEAM is safe and effective as a conditioning regimen in relapsed/refractory DLBCL.
Cancer Medicine 08/2014; 3(4). DOI:10.1002/cam4.247 · 2.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objective:
To compare the initial clinical, biological, and radiographic findings of early arthritis by positivity for rheumatoid factor (RF) and/or anticyclic citrullinated peptide antibodies (anti-CCP), and to validate a patient profile based on this serologic information.
The ESPOIR cohort comprises patients presenting synovitis of at least 2 joints for 6 weeks to 6 months. Patients underwent testing for IgM rheumatoid factor (IgM-RF) and anti-CCP2 antibodies and were divided into 4 groups: RF- and anti-CCP- (group 1), RF+ and anti-CCP- (group 2), RF- and anti-CCP+ (group 3), RF+ and anti-CCP+ (group 4). We compared the groups in terms of clinical, biological, and radiographic features (baseline scores and 6-month and 12-month progression).
Of the 813 recruited patients, 406 (50%) were in group 1, 91 (11.2%) in group 2, 34 (4.1%) in group 3, and 281 (34.6%) in group 4. Mean baseline erythrocyte sedimentation rate and C-reactive protein were higher for anti-CCP+ groups (groups 3 and 4) than for other groups (p < 0.001), and van der Heijde-modified Sharp score for radiographs was higher for group 4 than for other groups (p < 0.001). Clinical presentation was not consistently associated with serologic profile. Radiographic progression at 1 year was higher for anti-CCP+ groups than other groups (p < 0.001).
The phenotype of patients with early arthritis with or without anti-CCP and/or RF positivity did not correspond to a particular clinical presentation. However, baseline acute-phase reactants and short-term radiographic progression were high in patients with anti-CCP positivity, which may be associated with the inflammatory process and progressive disease in patients with early arthritis.
The Journal of Rheumatology 07/2014; 41(8). DOI:10.3899/jrheum.130884 · 3.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Data from the national French Renal Epidemiology and Information Network (REIN) registry were used to compare survival between transplant recipients under age 65 who resumed dialysis after graft failure during 2007-2009 and transplant-naïve incident dialysis patients matched for age, gender, diabetes mellitus, and year of starting dialysis. Among 911 transplant patients who returned to dialysis, 103 had died by 1 January 2011. Multivariate analysis showed that age over 48 years, coronary artery disease, peripheral artery disease, and inability to walk unassisted were significant predictors of death. In the case-control analysis, the observed mortality rates in 778 transplant failure and 778 transplant-naïve dialysis patients were 11.8 and 10.8%, respectively. Kaplan-Meier estimates of survival after transplant failure vs. the transplant-naïve controls were 95.2 vs. 94.1% at 1 year, 90.3 vs. 88.8% at 2 years, and 84.2 vs. 80.2% at 3 years (log rank P=0.197 overall). Dialysis in transplant failure vs. transplant-naïve patients was not associated with significantly increased mortality. At the start of dialysis, the serum creatinine levels and the rate of unplanned dialysis were significantly lower in transplant failure patients compared with transplant-naïve controls. Thus, in patients under 65 years of age in France, survival of dialysis patients after graft loss is similar to that of incident dialysis patients who have not undergone transplantation.Kidney International advance online publication, 19 February 2014; doi:10.1038/ki.2014.6.
Kidney International 02/2014; 86(1). DOI:10.1038/ki.2014.6 · 8.56 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Compared to dialysis, kidney transplantation appears to be the best treatment for chronic kidney failure, even for older aged patients. Nevertheless, the individual benefit of transplanting elderly patients has to be balanced against the corresponding increase in the number of patients awaiting grafts.
We analyzed the excess mortality related to kidney transplant recipients by taking into account the expected mortality of the general population (additive regression model for relative survival). We applied this method to a cohort of patients who received a first deceased-donor kidney transplant between 1998 and 2009 in France (DIVAT, n=3641).
Overall 10-year mortality was 13%. As expected, recipient age was the main risk factor associated with overall mortality. In contrast, recipient age was no longer significantly associated with the excess of mortality related to kidney transplant status by subtracting the expected mortality of the general population. Delayed graft function (DGF), pre-transplantation immunization and past history of diabetes appeared as the main risk factors of this higher mortality rate.
Our results constitute a strong argument in favor of kidney transplantation regardless the patient's age. Preventing DGF may be more effective for decreasing the risk of death specifically attributable to the disease. This article is protected by copyright. All rights reserved.
Transplant International 11/2013; 27(2). DOI:10.1111/tri.12241 · 2.60 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Survival curves are a popular tool for representing the association between a binary marker and the risk of an event. The separation between the survival curves in patients with a positive marker (high-risk group) and a negative marker (low-risk group) reflects the prognostic ability of the marker. In this article, we propose an alternative graphical approach to represent the discriminative capacity of the marker-a receiver operating characteristic (ROC) curve, tentatively named prognostic ROC curve-obtained by plotting 1 minus the survival in the high-risk group against 1 minus the survival in the low-risk group. The area under the curve corresponds to the probability that a patient in the low-risk group has a longer lifetime than a patient in the high-risk group. The prognostic ROC curve provides complementary information compared with survival curves. However, when the survival functions do not reach 0, the prognostic ROC curve is incomplete. We show how a range of possible values for the area under the curve can be derived in this situation. A simulation study is performed to analyze the accuracy of this methodology, which is also illustrated by applications to the survival of patients with brain metastases and survival of kidney transplant recipients.
[Show abstract][Hide abstract] ABSTRACT: Patients with CKD display altered plasma amino acid profiles. This study estimated the association between the estimated GFR and urinary and plasma amino acid profiles in CKD patients.
Urine and plasma samples were taken from 52 patients with different stages of CKD, and plasma samples only were taken from 25 patients on maintenance hemodialysis. Metabolic profiling was performed by liquid chromatography coupled with tandem mass spectrometry after phenylisothiocyanate derivatization.
Most plasma amino acid concentrations were decreased in hemodialysis patients, whereas proline, citrulline, asparagine, asymmetric dimethylarginine, and hydroxykynurenine levels were increased (P<0.05). Both plasma levels and urinary excretion of citrulline were higher in the group of patients with advanced CKD (CKD stages 2 and 3 versus CKD stages 4 and 5; in plasma: 35.9±16.3 versus 61.8±23.6 µmol/L, P<0.01; in urine: 1.0±1.2 versus 7.1±14.3 µmol/mol creatinine, P<0.001). Plasma asymmetric dimethylarginine levels were higher in advanced CKD (CKD stages 2 and 3, 0.57±0.29; CKD stages 4 and 5, 1.02±0.48, P<0.001), whereas urinary excretion was lower (2.37±0.93 versus 1.51±1.43, P<0.001). Multivariate analyses adjusting on estimated GFR, serum albumin, proteinuria, and other covariates revealed associations between diabetes and plasma citrulline (P=0.02) and between serum sodium and plasma asymmetric dimethylarginine (P=0.03). Plasma tyrosine to phenylalanine and valine to glycine ratios were lower in advanced CKD stages (P<0.01).
CKD patients have altered plasma and urinary amino acid profiles that are not corrected by dialysis. Depending on solutes, elevated plasma levels were associated with increased or decreased urinary excretion, depicting situations of uremic retention (asymmetric dimethylarginine) or systemic overproduction (citrulline). These results give some insight in the CKD-associated modifications of amino acid metabolism, which may help improve their handling.
Clinical Journal of the American Society of Nephrology 11/2013; 9(1). DOI:10.2215/CJN.06000613 · 4.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Amyotrophic lateral sclerosis (ALS) is an incurable paralytic disorder primarily typified by the selective and progressive degeneration of motoneurons in the brain and spinal cord. ALS causes muscle wasting and atrophy, resulting eventually in respiratory failure and death within 3-5 years of diagnosis. Vitamin D is a potent secosteroid hormone with diverse biological functions that include protection against neuronal damage. The detrimental consequences of vitamin D dietary deficiency have been documented in other neurodegenerative diseases. However, the protective effect of vitamin D on motoneuron and the influence of its levels on disease course remains elusive. Here we found that the biologically active form of vitamin D significantly potentiated the effect of neurotrophic factors and prevented motoneurons from a Fas-induced death, while electrophysiological properties of motoneurons were not affected. In ALS patients, we report that a severe vitamin D deficiency accelerates by 4 times the rate of decline and were associated with a marked shorter life expectancy. Our findings support a neuroprotective function of vitamin D on motoneurons and propose vitamin D as a reliable prognostic factor of ALS.
Neurobiology of aging 11/2013; 35(5). DOI:10.1016/j.neurobiolaging.2013.11.005 · 5.01 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To report the 5-year outcome of a large prospective cohort of patients with very early rheumatoid arthritis (RA), and to identify factors predictive of outcome.
Patients were recruited if they had early arthritis of < 6 months' duration, had a high probability of developing RA, and had never been prescribed disease-modifying antirheumatic drugs (DMARD) or steroids. Logistic regression analysis was used to determine factors that predict outcome.
We included 813 patients from December 2002 to April 2005. Age was 48.1 ± 12.6 years, delay before referral 103.1 ± 52.4 days, 28-joint Disease Activity Score (DAS28) 5.1 ± 1.3, Health Assessment Questionnaire (HAQ) 1.0 ± 0.7; 45.8% and 38.7% had rheumatoid factor or antibodies to cyclic citrullinated peptide (anti-CCP), respectively; 22% had hand or foot erosions; 78.5% fulfilled the American College of Rheumatology/European League Against Rheumatism criteria for RA at baseline and 93.8% during followup. At 5 years, 573 patients were evaluated. The outcome was mild for most patients: disease activity (median DAS28 = 2.5) and HAQ disability (median 0.3) were well controlled over time; 50.6% achieved DAS28 remission and 64.7% low disease activity. Radiographic progression was low (2.9 Sharp unit/year) and only a few patients required joint surgery. Nevertheless, some patients developed new comorbidities. During the 5 years, 82.7% of patients had received at least 1 DMARD (methotrexate, 65.9%), 18.3% a biological DMARD, and about 60% prednisone at least once. Anti-CCP was the best predictor of remaining in the cohort for 5 years, of prescription of synthetic or biologic DMARD, and of radiographic progression.
The 5-year outcome of an early RA cohort in the 2000s was described. Anti-CCP was a robust predictor of outcome. The generally good 5-year outcome could be related to early referral and early effective treatment, key processes in the management of early RA in daily practice.
The Journal of Rheumatology 08/2013; 40(10). DOI:10.3899/jrheum.121515 · 3.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background:
The incidence and number of circulating tumor cells (CTCs) in the peripheral blood of colorectal cancer patients are lower than in other cancer types, which may point to a particular biology of colorectal cancer affecting CTC detection.
We detected CTCs in the peripheral and mesenteric blood of colorectal cancer patients by use of 2 independent technologies on the basis of different biological properties of colon cancer cells. Seventy-five patients diagnosed with localized (M0, n = 60) and metastatic (M1, n = 15) colorectal cancer were included. Peripheral and mesenteric blood samples were collected before tumor resection. We performed CTC enumeration with an EpCAM-independent enrichment method followed by the Epispot assay that detected only viable CK19-releasing CTCs. In parallel, we used the FDA-cleared EpCAM-dependent CellSearch® as the reference method.
The enumeration of CK19-releasing cells by the CK19-Epispot assay revealed viable CTCs in 27 of 41 (65.9%) and 41 of 74 (55.4%) (P = 0.04) patients in mesenteric and peripheral blood, respectively, whereas CellSearch detected CTCs in 19 of 34 (55.9%) and 20 of 69 (29.0%) (P = 0.0046) patients. In mesenteric blood, medians of 4 (range 0-247) and 2.7 CTCs (range 0-286) were found with Epispot and CellSearch (P = 0.2), respectively, whereas in peripheral blood, Epispot and CellSearch detected a median of 1.2 (range 0-92) and 0 CTCs (range 0-147) (P = 0.002).
A considerable portion of viable CTCs detectable by the Epispot assay are trapped in the liver as the first filter organ in CRC patients.
[Show abstract][Hide abstract] ABSTRACT: Androgens are critical in male external genital development. Alterations in the androgen sensitivity pathway have been identified in severely undermasculinized boys, and mutations of the androgen receptor gene (AR) are usually found in partial or complete androgen insensitivity syndrome (AIS).
The aim of this study was to determine whether even the most minor forms of isolated hypospadias are associated with AR mutations and thus whether all types of hypospadias warrant molecular analysis of the AR.
Two hundred and ninety-two Caucasian children presenting with isolated hypospadias without micropenis or cryptorchidism and 345 controls were included prospectively. Mutational analysis of the AR through direct sequencing (exons 1-8) was performed. In silico and luciferase functional assays were performed for unreported variants.
Five missense mutations of the AR were identified in 9 patients with glandular or penile anterior (n = 5), penile midshaft (n = 2) and penile posterior (n = 2) hypospadias, i.e., 3%: p.Q58L (c.173A>T), 4 cases of p.P392S (c.1174C>T), 2 cases of p.A475V (c.1424C>T), p.D551H (c.1651G>C) and p.Q799E (c.2395C>G). None of these mutations was present in the control group. One mutation has never been reported to date (p.D551H). It was predicted to be damaging based on 6 in silico models, and in vitro functional studies confirmed the lowered transactivation function of the mutated protein. Three mutations have never been reported in patients with genital malformation but only in isolated infertility: p.Q58L, p.P392S, and p.A475V. It is notable that micropenis, a cardinal sign of AIS, was not present in any patient.
AR mutations may play a role in the cause of isolated hypospadias, even in the most minor forms. Identification of this underlying genetic alteration may be important for proper diagnosis and longer follow-up is necessary to find out if the mutations cause differences in sexual function and fertility later in life.
PLoS ONE 04/2013; 8(4):e61824. DOI:10.1371/journal.pone.0061824 · 3.23 Impact Factor