Biomedical subjects

R Ecochard

Publications and source records attributed to R Ecochard.

At least 19 recordsLinked to original sources

PubMed2007

Application of the promotion time cure model with time-changing exposure to the study of HIV/AIDS and other infectious diseases.

Infectious diseases are caused by single or successive contacts with pathogens. Nevertheless, contacts with pathogens do not implicate infection. In 1993, Yakovlev et al. proposed a model to study a population of cancer patients with a cured fraction, a well adapted model to describe an infectious disease with a unique infection occasion. Extensions of this model have been proposed in the recent years. We present a mechanistic formulation in the context of infectious diseases with multiple infection occasions. It is a mixture model that enables to study risk factors associated with infection intensity at each infection occasion and factors shortening the delay from exposure to clinical event. Simulations are performed to evaluate the model fitting and two examples are presented for illustration: an analysis of an HIV-1 mother-to-child transmission data set and an analysis of nosocomial urinary tract infections data set.

Communicable Diseases↗

PubMed2006

Screening for multidrug-resistant bacteria as a predictive test for subsequent onset of nosocomial infection.

OBJECTIVE: To investigate whether carriage of multidrug-resistant bacteria is a risk factor for nosocomial infection and whether detection of carriage is predictive of subsequent onset of nosocomial infection. METHODS: In this observational cohort (study period, June 1998 through October 2002), nasal and rectal swab specimens from 412 consecutive patients admitted to the intensive care unit were tested for carriage of multidrug-resistant bacteria. Concomitantly, the bacteria responsible for any subsequent nosocomial infection, the date of infection, and some of the known clinical risk factors for nosocomial infection were noted. These factors were adjusted for potential confounders, using a Cox model stratified on the propensity score of multidrug-resistant bacteria carriage. The diagnostic characteristics of a carriage test, including the positive and negative diagnostic likelihood ratios, were calculated for all strata of the propensity score. RESULTS: Forty-two patients were carrying multidrug-resistant bacteria. Nosocomial infection occurred in 95 patients, of whom 16 (38%) were carriers, and 79 (83%) were noncarriers (P=.01). After adjustment for potential confounders, statistical analysis revealed that carriage remained a risk factor for nosocomial infection (relative risk, 2.08 [95% confidence interval {CI}, 1.13-3.81]). Receipt of antibiotic treatment at the time of intensive care unit admission was found to be protective against nosocomial infection. A positive result of test for detection of carriage seemed to be an efficient predictor of subsequent nosocomial infection (positive diagnostic likelihood ratio, 2.05 [95% CI, 1.15-3.66]), although a negative test result was not a predictor of subsequent nosocomial infection (negative likelihood ratio, 0.91 [95% CI, 0.73-1.11]). CONCLUSION: Carriage proved to be a risk factor for subsequent nosocomial infection. However, the carriage test was useful as a predictive tool only for patients with a positive test result.

Aged↗

PubMed2006

Plaque density on CT, a potential marker of ischemic stroke.

The authors sought to determine in a retrospective analysis whether carotid plaque soft TD on CT is associated with recent ischemic neurologic events. Among 141 patients (99 asymptomatic), 106 plaques with more than 50% stenosis were selected for density measurements. They found an odds ratio for neurologic events associated with a 10-point decrease in density of 1.54 (p = 0.002), showing an association between plaque density and neurologic events.

Aged↗

PubMed2006

Estimates of the number of cancer patients hospitalized in a geographic area using claims data without a unique personal identifier.

OBJECTIVE: In French national claims databases, claims are currently anonymous i.e. not linked to individual patients. In order to improve our estimate of the medical activity related to cancer in one French region, a statistical method was developed to use claims data to assess the number of cancer patients hospitalized in acute care. METHODS: This method used the medical and administrative information available in the claims (i.e. age, primary site, length of stay) to predict an average number of stays per patient, followed by a number of patients. It was based on a two-phase study design using an internal dataset which contained personal identifiers to estimate the model parameters. RESULTS: The predicted number of acute care patients hospitalized in one or several health care centers in one French region was 38,109 with a 95% predictive interval (37,990; 38,228) for the first six months of 2002. A prediction error of 24 per thousand was found. CONCLUSION: We provide a good estimate of the morbidity in acute care hospitals using claims data that is not linked to individual patients. This estimate reflects the medical activity and can be used to anticipate acute care needs.

Adolescent↗

PubMed2005

[Incidence of cardiovascular events in giant cell arteritis: preliminary results of a prospective double cohort study (GRACG)].

UNLABELLED: Giant cell arteritis is the most frequent vasculitis. Cardiovascular events such as cerebrovascular accident or ischemic heart disease may occur in patients with giant cell arteritis. However, their real incidence, as well as their relative risk compared to the general population, remains unknown. PURPOSE: To assess in a prospective, double cohort study, the incidence of cardiovascular events in giant cell arteritis patients compared to controls, after controlling for cardiovascular risk factors. PATIENTS AND METHODS: We included on predefined criteria 432 newly diagnosed patients with giant cell arteritis, each assigned to sex- and age-matched controls randomly selected from the general population. Cardiovascular risk factors (high-blood pressure, diabetes, smoking, hypercholesterolemia and preexisting peripheral vascular disease) were collected at inclusion. During the 24-month follow-up, all cardiovascular events were collected. After stratification for cardiovascular risk factors, a log-rank test was performed to compare cases and controls. A parametric survival model was used for multivariate analysis. RESULTS: Cardiovascular events all combined were significantly increased in patients with giant cell arteritis (RR = 2.15 [1.21-3.81], P = 0.009), and were mainly associated with age (P = 0.0001), past history of cardiovascular disease (P = 0.023) but also with giant cell arteritis (P = 0.009). However, each subset of cerebrovascular accident (RR = 2.42 [0.84-7]) or ischemic heart disease (RR = 1.67 [0.72-3.89]) increased but did not significantly. CONCLUSION: Cardiovascular events incidence is increased in patients with giant cell arteritis, and prescription of preventive antiagregant treatment may be discussed.

Aged↗

PubMed2005

Glucose-lipid ratio is a determinant of nitrogen balance during total parenteral nutrition in critically ill patients: a prospective, randomized, multicenter blind trial with an intention-to-treat analysis.

OBJECTIVE: Protein sparing, the major goal of nutritional support, may be affected by the glucose/lipid ratio. This study in critically ill patients compared the efficacy and tolerance of two isocaloric isonitrogenous total parenteral nutritions (TPN) having different glucose/lipid ratios. DESIGN: Multicentric prospective randomized study. PATIENTS: 47 patients with SAPS I score higher than 8 and requiring exclusive TPN. INTERVENTIONS: Patients received glucose/lipid ratios of 50/50 or 80/20. For 7 days all patients received 32 glucidolipidic kcal/kg and 0.27 g/kg nitrogen daily. All-in-one bags were prepared using industrial mixtures and a fat emulsion. MEASUREMENTS AND RESULTS: We determined TPN efficacy by nitrogen balance, urinary 3-methylhistidine/creatinine ratio, transthyretin and tolerance by glycemia, and liver enzymes. After controlling for five variables with significant effects, patients receiving the 50/50 ratio during TPN had significantly higher nitrogen balance than those receiving the 80/20 ratio. The daily difference in mean nitrogen sparing effect in favor of the latter group was 1.367 g (95% CI 0.0686-2.048). Glycemia on day 4 and gamma-glutamyltranspeptidase on day 8 were higher in group receiving the the 80/20 ratio. CONCLUSIONS: In critically ill patients TPN at a glucose/lipid ratio of 80/20 ratio induces a small nitrogen sparing effect compared to the ratio of 50/50, at the expense of poorer glycemic control. The clinical significance is unclear.

Critical Care↗

PubMed2005

Modelling the progression towards duodenal cancer among patients with familial polyposis on the basis of two different score profiles.

The objective was to design a method that considers, on clinical arguments, the likely existence of patient subgroups with different evolution profiles. The method is applied in familial adenomatous polyposis to predict the proportion of patients that would develop duodenal cancer. A subject-specific linear mixed-effects model was elaborated to explicitly model heterogeneity in regression parameters. The estimates of the parameters were obtained by Bayesian inference using Gibbs sampling. The application concerned two potential polyposis subgroups: stable-state and progressive. Each patient's score was expressed in function of his putative subgroup, the reference subgroup mean score (intercept), the rate of change (slope), and time. The estimated proportion of stable-state patients was 35%. In progressive-state patients, the estimated annual score increase was 0.38 (95% CI: 0.27-0.48). The regression model predicted that the proportion of patients with a score > or = 9 is near 43% at age 60 (36-50%) and 50% at 70 (43-57%). The method indicates the evolution profile of each subject, which facilitates therapeutic decisions. The modelling may be extended to other more complex situations with several subgroups, with different change rates, or with various genetic or therapeutic profiles.

Adenomatous Polyposis Coli↗

PubMed2005

Heterogeneity, the masked part of reproductive technology success rates.

BACKGROUND: Heterogeneity in women and men's fecundity is a well-established fact. The selection process of men and women treated for infertility might bias the success rates of reproductive technology. Bias may also arise from frequency and timing of intercourse with respect to the day of ovulation. METHODS: Several datasets were collected and analysed. They concern normally fertile couples who used natural family planning methods and infertile couples treated by artificial insemination with husband or donor's spermatozoa. The effects of heterogeneity on the success rates of treatment cycles are described and solutions are proposed as to data collection and statistical analysis in this specific field. RESULTS: The decrease in the success rates along successive cycles of assisted reproduction is a consequence of heterogeneity. The probability of conception varies among women and among men. After a first success, the probability of another success is higher. After a failure, the probability of success is lower. The most specialised centres treat the less fecund couples. There is a negative correlation between men and women's fertility in case of oligo/azoospermia. The fecund window cannot be correctly located by calendar calculations, but more appropriately by assessment of cervical mucus at the vulva. The variability of this location is wide. The decrease in the success rate with men and women's age results from a complex mixture of an increase in the proportion of sterile patients and a decrease in fecund patients' fecundity. CONCLUSION: Care should be taken to limit the bias due to patient selection and specific statistical methods should be used to allow for the progressive selection of patients during fertility studies and for the variability of the frequency and the timing of intercourse or insemination relative to ovulation.

Data Interpretation, Statistical↗

PubMed2004

Should age influence the choice of quantitative bone assessment technique in elderly women? The EPIDOS study.

In a prospective cohort of 7,598 women aged 75 and over, we analyzed the effect of age on the ability of femoral neck bone mineral density (BMD) and of ultrasound (BUA and SOS) of the calcaneus to predict hip fracture. Unadjusted regression analysis showed that the risk of hip fracture was increased 1.7 times for one standard deviation increase in age (3.7 years). Overall, for a decrease of one standard deviation in quantitative bone measures, the risk was significantly increased by 2.2 times for BMD (1.9-2.5), 1.8 for BUA (1.6-2.1), and 1.9 for SOS (1.6-2.2). However the average relative risk associated with a decrease in BMD tends to diminish with advancing age, meaning that a smaller part of the risk is explained by BMD in the very elderly. This is confirmed by the areas under the ROC curves (AUC) of BMD that are significantly better before 80 years (0.75 [0.73-0.76]) than after (0.65 [0.63-0.67] in group 80-84 years and 0.65 [0.61-0.68] in group >/=85). On the other hand, as the absolute risk increases exponentially with age, the number of hip fractures attributable to a low BMD is still important in the very elderly, the risk difference between the lowest and the highest quartile of BMD is 25 hip fractures / 1,000 woman-years in the group >/=85 compared with 16 in the two other groups. Thus, after 80, quantitative assessment of bone may still be of interest for clinical decisions. Compared with quantitative ultrasound parameters, the ability of BMD to predict hip fracture was significantly superior to that of BUA and SOS only before the age of 80 (AUC of BMD 0.75 [0.73-0.76], BUA 0.67 [0.66-0.69], SOS 0.67 [0.65-0.69]). For patients older than 80, we did not observe significant differences in AUC between DXA and QUS to predict hip fracture.

Absorptiometry, Photon↗

PubMed2003

Risk of occupational blood exposure in a cohort of 24,000 hospital healthcare workers: position and environment analysis over three years.

Early and efficient prevention of occupational blood exposure at hospital requires knowledge of exposures and risks according to staff characteristics. Calculation of annual exposure rates and relative rates from personal and occupational data. The overall annual incidence was 3.5 per 100 workers per year; maximum for nurses and midwives (6.5); minimum for cleaners and paramedics (0.6). Exposures affected mainly nurses (57.81% of accidents, 12.12% of cohort) and occurred mostly in the surgical and the medical departments (26.34 and 25.20% of accidents). Men/women and students/physicians rate differences were not significant. Emergency and intensive care staffs had the highest relative rates (4.27 and 3.05) compared with maintenance staff. Nurses and laboratory staff were more exposed than physicians (3.76 and 2.30 times) were. Our results prompt prevention and training to be precisely focused and efficiently devised.

Adult↗

PubMed2003

[Missing data mechanisms of the questionnaire SF-36's items in the SU.VI.MAX study].

BACKGROUND: Health related quality of life is becoming of greater importance in the medical field. Nevertheless, methodological problems persist, and particularly when it comes to processing missing data on quality of life questionnaires. In fact, this leads to three difficulties: (i) loss of power; (ii) bias; (iii) choice of the most adequate method for treating missing data. Prevention is the best recommendation in order to avoid unanswered questions. Unfortunately, this does not guarantee the absence of missing data. Therefore, the treatment of missing data depends on: i) identification of the missing data mechanism and ii) choice of the most appropriate method to correct the data. The main objective of this article is to illustrate the identification of non-response items as described in the SF-36 questionnaire items in the SU.VI.MAX study. METHODS: A logistic regression on the characteristics of the subjects was used to distinguish between two missing data mechanisms: missing completely at random (MCAR) and missing at random (MAR). Two global Chi-2 tests on MCAR mechanism were proposed. The missing data not at random (MNAR) mechanism was also analysed considering the questionnaire features. RESULTS: The percentage of non-responses was small (1.7%), with a maximum equal to 3% for four questions of the General Health dimension (GH2 to GH5). Both global Chi-2 tests rejected the hypothesis that all SF-36 non-responses were MCAR. As to the 32 items with less than 2.3% of non-responses, the mechanisms were: MCAR for 29 items, MAR for 2 items, and probably MNAR for 1 item. The logistic regression indicates that the factors related to non-responses were gender (female), age (> or =50 years), attention problem, and number of children (> or =3). The hierarchical feature of item PF5 (climb one flight of stairs) in relation to PF4 (climb several flights of stairs) would be a generator MNAR non-responses. The "I don't know" response modality of bloc GH2 to GH5 would also be generator of non-responses of the MNAR type. CONCLUSION: The identification of missing data mechanisms through statistical analysis and through further reflection on the questionnaire's features is a necessary preliminary in the treatment of non-responses.

Adult↗

PubMed2002

[Worsening of heart failure during hospital course in myocardial infarction is a factor of poor prognosis. Apropos of a prospective cohort study of 2,507 patients hospitalized with myocardial infarction: the PRIMA study].

BACKGROUND: Worsening of heart failure in patients with myocardial infarction is seldom studied, elderly patients often are not included, and multivariate analysis is uncommon. AIMS: The prospective PRIMA study (Prise en charge de l'Infarctus du Myocarde Aigu; management of acute myocardial infarction) sought to determine the incidence of heart failure worsening, its risk factors, and its prognostic importance in patients with myocardial infarction, regardless of age and hospital facilities, in the "real world" in a region in France, using multivariate analysis. METHODS: Data were prospectively collected in all patients with myocardial infarction admitted in all hospitals in three departments in the Rhône-Alpes region in France between September 1, 1993 and January 31, 1995. RESULTS: Among 2,507 patients, 33% were in Killip classes II-IV at admission. Four hundred and sixteen patients (17%) had worsening of Killip class during the first five days. In-hospital mortality (overall: 14%) increased dramatically with Killip class at admission (9% in class I; 62% in class IV) and with worsening of Killip class during the first five days (36% vs 8% if no worsening). In multivariate analysis, older age, diabetes mellitus and anterior Q-wave myocardial infarction were significant predictors of Killip class at admission and of its worsening. The significant predictors of in-hospital mortality were older age, Killip class III at admission and worsening of Killip class during the first five days. CONCLUSION: This large, unselected cohort revealed that among patients with myocardial infarction, heart failure and its worsening are frequent, especially in the elderly, and dramatically worsen the in-hospital mortality.

Aged↗

PubMed2002

Method of correction to assess the number of hospitalized incident breast cancer cases based on claims databases.

Estimations of the number of hospitalized incident cancer cases show biases when claims databases are used. This is due to false reports of incident cancer because of a lack of specificity, and because of unrecorded cancers resulting from a lack of sensitivity. We present a statistical method to provide corrected estimations. This method is based on a two-phase study design using an external data set for sensitivity and specificity estimates. Inaccuracy of the corrected number of hospitalized incident cancer cases was assessed by a credibility interval determined by a Bayesian approach using a Monte Carlo method. Based on the population hospitalized in a large group of French University hospitals, 334 women were identified in the French claims database as having potential incident cases of breast cancer in 1997. According to our method, the corrected number was 565 (550-580). In absence of hospital-based cancer registries, our approach provides estimates and credibility intervals, and has many potential applications in defining hospital policies with its applicability to other diseases.

Breast Neoplasms↗

PubMed2002

Color Doppler energy prediction of malignancy in adnexal masses using logistic regression models.

OBJECTIVE: The aim of this study was to assess the usefulness of color Doppler energy in the preoperative diagnosis of ovarian malignancy using multivariate logistic regression analysis. METHODS: One hundred and thirty adnexal masses were studied with transvaginal B-mode, color energy, and pulsed Doppler ultrasonography before surgery in order to develop a model that could be used to determine malignancy. Each ultrasonographic variable (tumor size, wall thickness, septal structure, echogenicity, papillary projection, density (solid or not)) was included individually or combined together as part of the Sassone ultrasound score. Intratumoral blood flow velocity waveforms were obtained to determine pulsatility index and resistance index and a more subjective parameter, location of tumor vascularity, was also assessed. Menopausal status and serum CA 125 levels were also entered as categorical variables. Sonographic parameters were entered alone, then associated with menopausal status and CA 125 serum levels, and finally with Doppler energy measurements. Our model was then validated in a group of 68 adnexal masses and compared to the model of Alcazar. RESULTS: Eighteen adnexal masses (13.8%) were malignant or of low malignant potential. Multivariate analysis showed that papillary projection of the tumor wall, cyst with solid parts, resistance index with a cut-off value of 0.53, CA 125, and central blood flow location, were the only factors to be independent predictors of malignancy. Menopausal status was not an independent factor. For the final model including the Doppler energy parameter the best sensitivity and specificity were 83% and 93%, respectively, at a cut-off value of 10% probability of malignancy compared to 83% and 87% for the morphological variables alone. Validation of the model showed its diagnostic performance to be as good as that reported in the original population and better than the model of Alcazar. CONCLUSION: Sonographic analysis of adnexal masses including color Doppler energy shows the best predictive properties according to histological diagnosis, and improves preoperative diagnosis of malignancy.

Adolescent↗

PubMed2002

Two-phase study to assess the number of cases based on claims databases: characteristics of the validation data set.

OBJECTIVE: In a two-phase study design, the characteristics of an external data set were studied for precision and bias of the number of incident or prevalent cases of a disease obtained from claims databases. METHODS: In the study population (first phase), incident or prevalent cases were counted whereas external data (second phase) provided sensitivity and specificity estimates to count cases in a claims database. Influence of potential differences in sensitivity and specificity between the two phases were evaluated. This was illustrated for 50-90% sensitivity and 99-99.99% specificity ranges. RESULTS AND CONCLUSIONS: The impact of differences in sensitivity and specificity depends on the odds of disease in the study population. We provide advice on the choice of adequate data sets to correct claims database estimates.

Bias↗

PubMed2001

Serological rebound in congenital toxoplasmosis: long-term follow-up of 133 children.

UNLABELLED: Although serological rebound is common in infants with congenital toxoplasmosis, clinical recommendations for management, in particular the need for additional treatment, vary. The goals of our retrospective cohort study in 133 consecutive children with congenital toxoplasmosis were to estimate the incidence and duration of the rebounds, identify predictive factors, assess the long-term risk of eye lesions and the need for treatment. We first estimated the incidence and duration of rebounds and identified predictive factors using an univariate analysis and a Cox model modified to include time-dependent variables. Two cohort studies were then conducted to compare the incidence density of secondary eye lesions in children who had a rebound versus no rebound, and among children who had a rebound after initial therapy, in those who received an additional course of treatment and in those who did not. Of the 133 children, 93 (70%) had at least one rebound during a mean follow-up of 95 months. Of those with one rebound diagnosed after initial treatment, 33 received an additional 3-month course of pyrimethamine/sulphadoxine and 48 were not treated. Intracranial calcification at birth was associated with an increased relative risk (RR) of rebound (RR = 2.601; P = 0.03), and treatment with pyrimethamine/sulphadoxine between 2 and 12 months of age with a decreased risk (RR = 0.3; P = 0.0845), whereas age of pregnancy at maternal infection, type of treatment during pregnancy and sex were not found to be predictive factors. There was no difference in incidence densities of secondary eye lesions in children without rebound (7/3,367 child-months) compared to those with at least one rebound (22/9,609 child-months) (RR = 1.10; 95% CI: 0.47-2.58), and, among the 81 children who had one rebound diagnosed after initial treatment, in those who received an additional course of treatment and in those who did not (RR = 0.72; 95% CI: 0.30-1.72). CONCLUSION: serological rebound is common in children with congenital toxoplasmosis but, due to the risk and constraints, an additional course of treatment and more ophthalmological surveillance than currently practiced do not seem warranted.

Animals↗

PubMed2001

Maternity hospitals ranking on prophylactic caesarean section rates: uncertainty associated with ranks.

OBJECTIVE: Ranking maternity hospitals on prophylactic caesarean section rates. STUDY DESIGN: The study population was a sample of 8470 women having delivered in the 86 maternity hospitals of the Rhône-Alpes region (France) in 1990. A two-level logistic model and the Gibbs sampling method were used to estimate the adjusted rate and rank of each maternity hospital with their 95% credible interval. RESULTS: Ranking of maternity hospitals was substantially modified after adjusting for differences in case-mix. The 95% credible intervals of the ranks were generally wide and overlapping. No maternity hospital could be confidently placed in the upper quarter nor in the lower quarter of the league table. CONCLUSION: The use of ranks based on rates to compare hospitals may be seriously misleading; thus, league tables need an accompanying reading guide. Furthermore, some rules should be respected, including the need to make accurate case-mix adjustments, to reduce the rate instability in smaller hospitals, and to highlight the uncertainty associated with ranks.

Cesarean Section↗

PubMed2001

Gonadotropin level abnormalities in women with cyclic mastalgia.

OBJECTIVES: Women with cyclic mastalgia seem to be at risk of fibrocystic breast disease and/or breast cancer. We studied the relationships between mastalgia and hormone levels throughout the menstrual cycle. STUDY DESIGN: Ostensibly healthy women were monitored during a sum of 326 cycles. A case-control study compared personal and hormonal variables of 30 women experiencing cyclic mastalgia with those of 77 women without this symptom. RESULTS: Except sleeping times, no significant differences were found in personal variables. Cyclic mastalgia and symptoms of fluid retention were slightly associated. Menses and the luteal phase were significantly longer in cases than in controls. Gonadotropin but not ovarian hormone levels were also significantly higher in cases throughout the cycle. CONCLUSION: Cyclic mastalgia is less related to symptoms of fluid retention or to ovarian hormone levels than to regularly high gonadotropin levels, specific inhibitors might thus be used to alleviate the symptom.

Adult↗