scholarly journals An optimal Wilcoxon–Mann–Whitney test of mortality and a continuous outcome

2016 ◽  
Vol 27 (8) ◽  
pp. 2384-2400 ◽  
Author(s):  
Roland A Matsouaka ◽  
Aneesh B Singhal ◽  
Rebecca A Betensky
Keyword(s):  
Clinical Trial ◽  
Composite Endpoint ◽  
Test Statistic ◽  
Continuous Outcome ◽  
Normobaric Oxygen ◽  
Whitney Test ◽  
Optimal Weights ◽  
Mann Whitney Test ◽  
Normobaric Oxygen Therapy

We consider a two-group randomized clinical trial, where mortality affects the assessment of a follow-up continuous outcome. Using the worst-rank composite endpoint, we develop a weighted Wilcoxon–Mann–Whitney test statistic to analyze the data. We determine the optimal weights for the Wilcoxon–Mann–Whitney test statistic that maximize its power. We derive a formula for its power and demonstrate its accuracy in simulations. Finally, we apply the method to data from an acute ischemic stroke clinical trial of normobaric oxygen therapy.

scholarly journals Morphology of renal pelvis and clearance of lower pole stones following ESWL

2003 ◽  
Vol 56 (11-12) ◽  
pp. 503-506
Author(s):  
Jovo Bogdanovic ◽  
Jovan Stojkov ◽  
Jasenko Djozic ◽  
Goran Marusic ◽  
Vuk Sekulic
Keyword(s):  
Successful Outcome ◽  
Lower Pole ◽  
Intravenous Pyelography ◽  
Whitney Test ◽  
Stone Fragmentation ◽  
Mann Whitney Test ◽  
Extracorporeal Shock Wave ◽  
Group I ◽  
Group Ii

Introduction and objective A prerequisite for successful outcome of extracorporeal shock wave lithotripsy (ESWL) is effective stone fragmentation. Despite successful stone fragmentation, complete clearance of stone fragments cannot be achieved patient, due to various factors. The aim of this prospective study was to determine morphological factors that affect clearance following successful stone fragmentation by ESWL. Material and methods In the period October 1999 and January 2001, 60 patients (45 male and 15 female) with single lower pole kidney stones have been treated using lithotripter Lithostar 2000TM. Parameters of radiographic anatomy, measured on intravenous pyelography, included infundibular width and length, infundibuloureteral infundibulopelvic angles. After the follow-up period of 3 months, patients were divided into two groups regarding clearance status: Group I consisted of stone free patients, and group II of those with residual fragments. Results Average values of measured parameters in group I vs group II were as follows: infundibular length 27.70?5.48 mm vs 30.25?3.95mm (p=0.045, Mann-Whitney test); infundibular width 5.98?3.28 mm vs 4.70?1.30 mm (p=0.018, Mann-Whitney test); infundibulopelvic angle 52.92?20.76o vs 34.10?8.19o (p=0.00001, Mann-Whitney test); infundibuloureteral angle 48.00?21.13o vs 30.70?7.49o (p=0.00001, Mann-Whitney test). Conclusion This study revealed that parameters of infundibulopelvic anatomy were significantly different in the examined groups. The success of clearance of fragments following ESWL procedure can be predicted using these morphologic parameters.

Confidence intervals for the Mann–Whitney test

2018 ◽  
Vol 28 (12) ◽  
pp. 3755-3768 ◽  
Author(s):  
Maja Pohar Perme ◽  
Damjan Manevski
Keyword(s):  
Confidence Intervals ◽  
Effect Size ◽  
Coverage Probability ◽  
Random Variable ◽  
Small Sample ◽  
Test Statistic ◽  
Whitney Test ◽  
Mann Whitney Test ◽  
Frequent Use ◽  
The Difference

The Mann–Whitney test is a commonly used non-parametric alternative of the two-sample t-test. Despite its frequent use, it is only rarely accompanied with confidence intervals of an effect size. If reported, the effect size is usually measured with the difference of medians or the shift of the two distribution locations. Neither of these two measures directly coincides with the test statistic of the Mann–Whitney test, so the interpretation of the test results and the confidence intervals may be importantly different. In this paper, we focus on the probability that random variable X is lower than random variable Y. This measure is often referred to as the degree of overlap or the probabilistic index; it is in one-to-one relationship with the Mann–Whitney test statistic. The measure equals the area under the ROC curve. Several methods have been proposed for the construction of the confidence interval for this measure, and we review the most promising ones and explain their ideas. We study the properties of different variance estimators and small sample problems of confidence intervals construction. We identify scenarios in which the existing approaches yield inadequate coverage probabilities. We conclude that the DeLong variance estimator is a reliable option regardless of the scenario, but confidence intervals should be constructed using the logit scale to avoid values above 1 or below 0 and the poor coverage probability that follows. A correction is needed for the case when all values from one sample are smaller than the values of the other. We propose a method that improves the coverage probability also in these cases.

scholarly journals TOI 1. Effect of Normobaric Oxygen Therapy on Wound Healing in Patients With Minor Tissue Loss from Critical Limb Ischemia: A Randomized Clinical Trial

2018 ◽  
Vol 68 (5) ◽  
pp. e148
Author(s):  
Piyaporn Prasartritha ◽  
Suthas Horsirimanont ◽  
Sopon Jirasiritham ◽  
Wiwat Tirapanich ◽  
Piyanut Pootracool ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Wound Healing ◽  
Randomized Clinical Trial ◽  
Critical Limb Ischemia ◽  
Oxygen Therapy ◽  
Limb Ischemia ◽  
Tissue Loss ◽  
Normobaric Oxygen ◽  
Normobaric Oxygen Therapy

Evaluation of At-home Bleaching Times on Effectiveness and Sensitivity with 10% Hydrogen Peroxide: A Randomized Controlled Double-blind Clinical Trial

2021 ◽  
Author(s):  
K Chemin ◽  
M Rezende ◽  
MC Costa ◽  
ADY Salgado ◽  
JL de Geus ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Hydrogen Peroxide ◽  
Repeated Measures ◽  
Rating Scale ◽  
Double Blind ◽  
Tooth Sensitivity ◽  
Once Daily ◽  
Whitney Test ◽  
Mann Whitney Test ◽  
At Home

SUMMARY Objectives: The aim of this randomized double-blind controlled clinical trial was to evaluate different protocols for at-home use of 10% hydrogen peroxide in whitening effectiveness and tooth sensitivity. Methods: Seventy-two patients were selected according to the inclusion and exclusion criteria, with the upper central incisors having color A2 or darker according to the Vita Classical scale (VITA Zahnfabrik, Bad Säckingen, Germany) and randomized into two groups: 10% hydrogen peroxide applied once daily for 15 minutes (HP 15) or applied once daily for 30 minutes (HP 30). Bleaching was performed for 14 days in both groups. The color was evaluated before bleaching, during bleaching (1st and 2nd weeks), and 1 month after the bleaching treatment using the Vita Classical, Vita Bleachedguide 3D-MASTER, and Vita Easyshade spectrophotometer (VITA Zahnfabrik). Dental sensitivity was recorded by the patients using the numerical rating scale (0–4) and visual analogue scale (0-10 cm). Color data were evaluated by two-way analysis of variance (ANOVA) of repeated measures (group vs. treatment time). The Mann-Whitney test was performed to contrast the means (α=0.05). Tooth sensitivity was assessed by Fisher’s exact test (p=1.00) and intensity of tooth sensitivity was evaluated by the Mann-Whitney test (α=0.05) for both scales. Results: A significant whitening effect was observed after 2 weeks of bleaching for all color measurements (p=0.01), with no difference between HP 15 and HP 30 (p>0.05). Also, the absolute risk and intensity of tooth sensitivity were similar (47%; p>0.05). Conclusions: The effectiveness and tooth sensitivity of at-home bleaching carried out with 10% hydrogen peroxide applied for 15 minutes or 30 minutes are similar.

Raised blast glutathione levels are associated with an increased risk of relapse in childhood acute lymphocytic leukemia

Blood ◽  
2001 ◽  
Vol 97 (2) ◽  
pp. 393-398 ◽  
Author(s):  
Pamela R. Kearns ◽  
Rob Pieters ◽  
M. M. Antoinette Rottier ◽  
Andrew D. J. Pearson ◽  
Andrew G. Hall
Keyword(s):  
Lymphoblastic Leukemia ◽  
Interindividual Variation ◽  
Rank Test ◽  
Test Statistic ◽  
Childhood All ◽  
Whitney Test ◽  
Log Rank Test ◽  
Mann Whitney Test ◽  
Increased Risk ◽  
Risk Of Relapse

Abstract A preliminary study has linked raised blast glutathione levels with chemoresistance in acute myeloid and lymphoblastic leukemia in adults and children. In this study, therefore, the relationship between leukemic blast glutathione levels and prognosis in childhood acute lymphoblastic leukemia (ALL) was investigated. A total of 77 childhood ALL samples were analyzed, 62 at initial presentation and 15 at relapse. A 20-fold interindividual variation in glutathione levels at presentation (median, 6.54 nmol/mg protein; range, 1.37 to 27.9) was demonstrated. The median level in T-lineage ALL was 2.3-fold higher than in B-lineage ALL (Mann-Whitney test,P < .0001). There was a significant correlation between presenting white cell count (WBC) and glutathione level (Spearman rank correlation coefficient, ρ = 0.45, P = .001). A high DNA index correlated with low glutathione levels (Mann-Whitney test,P = .013). There was no significant relationship between glutathione levels and in vitro drug sensitivity. Patients with glutathione levels above the median had a significantly greater risk of relapse (log-rank test statistic, 5.55; P = .018), and the overall survival rate was significantly reduced (log-rank test statistic, 4.38; P = .04). Multivariate analysis demonstrated that glutathione concentration was of independent prognostic value when assessed in conjunction with age, gender, WBC, and immunophenotype. The association of elevated blast glutathione levels with an increased risk of relapse suggests that glutathione-depleting agents may be of therapeutic value in patients who present with a high WBC.

Prädiktion des Return to Work nach Polytrauma bei Patienten mit einem ISS von 25 und höher

2019 ◽  
Vol 59 (02) ◽  
pp. 95-103
Author(s):  
Stefan Simmel ◽  
Simone Wurm ◽  
Sabine Drisch ◽  
Alexander Woltmann ◽  
Michaela Coenen
Keyword(s):  
Return To Work ◽  
Ältere Patienten ◽  
T Test ◽  
Berufliche Rehabilitation ◽  
Whitney Test ◽  
Mann Whitney Test

Zusammenfassung Ziel der Studie Die Überlebenschancen von Patienten auch mit schweren Polytraumata haben sich in den letzten Jahrzehnten kontinuierlich verbessert. Mitentscheidend für die Lebensqualität und Teilhabe dieser Patienten ist eine Rückkehr in das Erwerbsleben (Return-to-work (RTW)). Die Kenntnis, welche Faktoren RTW beeinflussen, ist relevant für die medizinische und berufliche Rehabilitation nach schweren Verletzungen. Ziel der Studie ist es zu analysieren, wie der RTW polytraumatisierter Patienten ins Erwerbsleben gelingt und welche Faktoren als Prädiktoren einen Einfluss auf RTW haben. Methodik Zur Bestimmung von Faktoren, die RTW vorhersagen, wurden in einer monozentrischen Studie von 84 Patienten im arbeitsfähigen Alter mit einem ISS von 25 oder höher Routinedaten aus dem Traumaregister der Klinik und im Follow-up Daten mittels des standardisierten Fragebogens POLO-Chart erfasst. Es wurden bivariate Analysen (Chi-Quadrat-Test, Wilcoxon Mann-Whitney-Test, t-Test) zum Zusammenhang mit RTW durchgeführt. Ausgewählte Variablen wurden in einem logistischen Regressionsmodell zur Prädiktion des RTW überprüft. Ergebnisse Insgesamt 58% der Patienten konnten in das Erwerbsleben zurückkehren. Das Alter, die Verweildauer auf der Intensivstation und der Zeitraum zwischen Entlassung aus der Klinik und der Befragung sind Prädiktoren für das RTW. Auch die Selbsteinschätzung des allgemeinen Gesundheitszustandes ist von entscheidender Bedeutung für die Rückkehr zur Arbeit, wohingegen in diesem Patientengut kein signifikanter Zusammenhang mit Vorerkrankungen oder als belastend erlebten Ereignissen bestand. Schlussfolgerung Das RTW von Patienten nach schwerem Polytrauma ist von verschiedenen Faktoren abhängig. Besonders ältere Patienten, die ihren allgemeinen Gesundheitszustand als schlecht einschätzen, haben Probleme in das Erwerbsleben zurückzukehren.

Efektifitas Penggunaan Metode Pembelajaran Simulasi Dengan Latihan Terhadap Keterampilan Pengisian Partograf Pada Mahasiswa Semester II Di Prodi Kebidanan (D-III) Universitas Kadiri Tahun 2015

2017 ◽  
Vol 4 (1) ◽  
pp. 12
Author(s):  
Dessy Lutfiasari ◽  
Mahmudah Mahmudah
Keyword(s):  
Current Method ◽  
Skills Training ◽  
Health Sciences ◽  
Control Group ◽  
Learning Methods ◽  
Control Group Design ◽  
Significance Level ◽  
Whitney Test ◽  
Mann Whitney Test ◽  
Training Simulation

The use of the current method of learning very big influence on the growth and development of students' creativity and interest for all subjects to be taught, especially in the use of partograf. From interviews to the 10 students of IV semester Prodi Midwifery (D-III) Kadiri University is known that 4 (40%) of students said it was understood, 4 (40%) of other students say they are confused and 2 (20%) of them said that he was a student not familiar with partograf. This shows the lack of understanding of students in filling partograph. The research objective is to determine the effectiveness of the use of learning methods for skills training simulation with filling partograph the second semester students in Midwifery (D-III) Kadiri University Faculty of Health Sciences in 2015. The research design used is pre experiment with design Static Group Comparison/Posttest Only Control Group Design. The population studied were all students of the second semester in Midwifery (D-III) Faculty of Health Sciences University of Kadiri numbered 50 students and sampling techniques Federer totaled 32 students. This is a research instrument partograph sheet. Results of the study were analyzed using the Mann Whitney test with a significance level of 0.05 were used.The results showed 7 respondents (46.7%) are adept at using partograf with simulation teaching methods and 6 respondents (40.0%) are adept at using partograph with practice learning methods. Data were analyzed by Mann Whitney test obtained ρ = 0.965; α = 0.05 means that H0 is accepted and H1 rejected. This means there is no difference in the effective use of learning methods for skills training simulation with partograph filling. Based on the results of this study are expected to choose the method of learning as a learning method in charging partograph because both methods equally effective.; Keywords: simulation methods, drilling methods, partograph filling

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