A propos de deux méthodes d'ajustement de modèles mathématiques non linéaires

peer reviewe

Safety of the Combination of PERC and YEARS Rules in Patients With Low Clinical Probability of Pulmonary Embolism: A Retrospective Analysis of Two Large European Cohorts

BACKGROUND: This study aimed to determine the failure rate of a combination of the PERC and the YEARS rules for the diagnosis of pulmonary embolism (PE) in the emergency department (ED). METHODS: We performed a retrospective analysis of two European cohorts of emergency patients with low gestalt clinical probability of PE (PROPER and PERCEPIC). All patients we included were managed using a conventional strategy (D-dimer test, followed, if positive, by computed tomographic pulmonary angiogram (CTPA). We tested a diagnostic strategy that combined PERC and YEARS to rule out PE. The primary endpoint was a thromboembolic event diagnosed in the ED or at 3-months follow-up. Secondary endpoints included a thromboembolic event at baseline in the ED and a CTPA in the ED. Ninety-five percent confidence intervals (CIs) of proportions were calculated with the use of Wilson\u27s continuity correction. RESULTS: We analyzed 1,951 patients (mean ± SD age = 47 ± 18 years, 56% women) with an overall proportion of patients with PE of 3.5%. Both PERC and YEARS strategies were associated with 11 missed PE in the ED: failure rate 0.57 (95% CI = 0.32-1.02). At 3-month follow-up, the overall failure rate was 0.83% (95% CI = 0.51-1.35). Among the 503 patients who underwent a CTPA (26%), the use of the PERC-YEARS combination would have ruled out PE without CTPA in 249 patients (50% [95%CI = 45%-54%], absolute reduction 13% (95% CI = 11%-14%]). CONCLUSION: The combination of PERC then YEARS was associated with a low risk of PE diagnostic failure and would have resulted in a relative reduction of almost half of CTPA

Improved ChIP-chip analysis by a mixture model approach

<p>Abstract</p> <p>Background</p> <p>Microarray analysis of immunoprecipitated chromatin (ChIP-chip) has evolved from a novel technique to a standard approach for the systematic study of protein-DNA interactions. In ChIP-chip, sites of protein-DNA interactions are identified by signals from the hybridization of selected DNA to tiled oligomers and are graphically represented as peaks. Most existing methods were designed for the identification of relatively sparse peaks, in the presence of replicates.</p> <p>Results</p> <p>We propose a data normalization method and a statistical method for peak identification from ChIP-chip data based on a mixture model approach. In contrast to many existing methods, including methods that also employ mixture model approaches, our method is more flexible by imposing less restrictive assumptions and allowing a relatively large proportion of peak regions. In addition, our method does not require experimental replicates and is computationally efficient. We compared the performance of our method with several representative existing methods on three datasets, including a spike-in dataset. These comparisons demonstrate that our approach is more robust and has comparable or higher power than the other methods, especially in the context of abundant peak regions.</p> <p>Conclusion</p> <p>Our data normalization and peak detection methods have improved performance to detect peak regions in ChIP-chip data.</p

Open placebo controlled comparison of the antiemetic effect of droperidol, metoclopramide or a combination of both in pediatric strabismus surgery.

In children, strabismus surgery is frequently followed by vomiting. The present study compares the antiemetic effects of droperidol (10 micrograms/kg) and/or metoclopramide (0.1 mg/kg) in 104 children undergoing strabismus surgery. The patients were randomly divided into four groups. Group I (n = 28) received placebo (saline), Group II (n = 26) droperidol 10 micrograms/kg, Group III (n = 25) metoclopramide 0.1 mg/kg and Group IV (n = 25) droperidol 10 micrograms/kg and metoclopramide 0.1 mg/kg. Droperidol was given just after induction and metoclopramide at the end of surgery, just before recovery. The technique of anesthesia involved an anticholinergic premedication, IV fentanyl (2 micrograms/kg), controlled ventilation using isoflurance and N2O in oxygen and systematic gastric emptying before extubation. Vomiting, retching and nausea were noted at 5 different moments: in the Post Anesthetic Care Unit, when arriving on the ward (= after carriage by lift), during the first hour following the return in the ward, from the 6th to the 12th postoperative hour and on the morning of day 1. There was no statistically significant difference in the incidence of vomiting among these four groups. Moreover, the incidence of vomiting in the placebo group was much lower (17.9% in the recovery room, 3.6% at return in the ward, 25% during the first hour, 7.1% from 6 to 12 hours and 3.6% the next day) than that reported in previous studies. We think that this could result from the additive effects of some aspects of the technique of anesthesia described and discussed in this paper