·P-58 Power and sample size calculations: A review and computer program

Dupont, William D.; Plummer, W. Dale

doi:10.1016/0197-2456(90)90157-w

Cited by 748 publications

(820 citation statements)

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“…We performed an a priori power analysis for Student's t test and for Fisher's exact test, which were to be used for the comparisons between the two groups at an alpha level of 0.05 using the PS program (http://biostat. mc.vanderbilt.edu/wiki/Main/PowerSampleSize) [14]. We regarded the following differences as clinically meaningful: greater than 50 mL in drained volume, 0.5 mg/dL in hemoglobin level, 10% in the incidence of bleeding-related wound problems, 10°motion arc, and 10% of maximum points in functional outcome scales.…”

Section: Methodsmentioning

confidence: 99%

Subcutaneous versus Intraarticular Indwelling Closed Suction Drainage after TKA: A Randomized Controlled Trial

Seo

Yoon

Koh

et al. 2010

Clinical Orthopaedics &Amp; Related Research

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Background TKA can involve substantial bleeding, and the issue regarding whether vacuum drainage should be used during TKA continues to be debated as both methods have disadvantages. Questions/purposes We therefore asked whether subcutaneous indwelling vacuum drainage is advantageous over intraarticular indwelling vacuum drainage in terms of blood drainage, bleeding-related complications, and functional outcomes in primary TKA. Patients and methods We randomized 111 patients undergoing TKAs to have either a subcutaneous indwelling or an intraarticular indwelling catheter and compared the two groups for blood loss (hemoglobin decrease, transfusion requirements, hypotension episode), incidence of wound problems (requirements for dressing reinforcement,

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Section: Methodsmentioning

confidence: 99%

Subcutaneous versus Intraarticular Indwelling Closed Suction Drainage after TKA: A Randomized Controlled Trial

Seo

Yoon

Koh

et al. 2010

Clinical Orthopaedics &Amp; Related Research

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“…[11,19,20]. According to the IRLSSG rating scale, severity was classified as mild (<11 on the IRLSSG rating scale), moderate (11)(12)(13)(14)(15)(16)(17)(18)(19)(20), severe (21)(22)(23)(24)(25)(26)(27)(28)(29)(30), and very severe (31)(32)(33)(34)(35)(36)(37)(38)(39)(40) [21]. The Page 6 of 35 prevalence of RLS found in that study was 26.6% (154/579).…”

Section: Methodsmentioning

confidence: 99%

“…The minimum number of subjects required to detect a ratio of median survival times (experimental group/control group) with a certain power and a two sided type I error probability of 5% was estimated [23,24]. A study power of 80% corresponds to a mean survival times ratio of 0.70 for the above given sample size of patients (154 with RLS) and controls (425 without RLS).…”

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confidence: 99%

Restless legs syndrome does not affect 3-year mortality in hemodialysis patients

et al. 2015

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Original Highlights of the studyWe evaluated the relationship of RLS and mortality in chronic hemodialysis patients For the diagnosis of RLS we implemented standard methodology, i.e. the essential clinical criteria of the International RLS Study Group. This is the first time this issue is investigated in an epidemiological survey in Greece.In contrast to previous reports the diagnosis of RLS does not influence the 3-year mortality in HD patients. ABSTRACTObjective: In chronic hemodialysis (HD) patients, the prevalence of restless legs syndrome (RLS) is significantly higher than in the general population. Uremic RLS has been related to an enhanced mortality of HD patients. In the general population, however, studies of this association have yielded inconsistent results. The aim of the present study was to re-evaluate the relationship of RLS and mortality in HD patients. Methods:We recorded the 3-year mortality rate in a population of 579 HD patients after assessment for RLS symptoms. In addition we analyzed the 5-year mortality rate after end-stage renal disease onset (i.e., commencement of HD). This HD patient population has been previously included in a cross-sectional survey of RLS prevalence in which RLS diagnosis was based on the essential clinical criteria of the International RLS Study Group. Mortality data were acquired from the national endstage renal disease registry. Survival probability was calculated by means of the Kaplan-Meier method and analyzed by the log-rank (Mantel-Cox) test. For multivariate survival analysis, we implemented a proportional hazards regression Conclusion: Diagnosis of RLS according to the essential clinical criteria of theInternational RLS Study Group does not seem to influence the 3-year mortality in HD patients. Our findings are in contrast to those in some previous reports, and reinforce the need for further studies of RLS and mortality in HD patients.

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“…Sample size was calculated according to Dupont and Plummer. 18 To account for possible dropouts, a sample size of 12 subjects was chosen for this trial.…”

Section: Magnetic Resonance Image Acquisitionmentioning

confidence: 99%

Neural effects of green tea extract on dorsolateral prefrontal cortex

et al. 2012

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BACKGROUND/OBJECTIVES: Green tea is being recognized as a beverage with potential benefits for human health and cognitive functions. In vivo studies provide preliminary evidence that green tea intake may have a positive role in improving effects on cognitive functions. We aimed to examine the neural effects of green tea extract on brain activation in humans. SUBJECTS/METHODS: Functional magnetic resonance imaging was recorded while 12 healthy volunteers performed a working memory task following administration of 250 or 500 ml of a milk whey based green tea containing soft drink or milk whey based soft drink without green tea as control in a double-blind, controlled repeated measures within-subject design with counterbalanced order of substance administration. A whole-brain analysis with a cluster-level threshold of Po0.001 (unadjusted) was followed by an a priori-defined region of interest (ROI) analysis of the dorsolateral prefrontal cortex (DLPFC) including a cluster-level threshold of Po0.05 and family-wise error (FWE) adjustment for multiple comparisons. RESULTS: Whole-brain analyses revealed no significant effects after correction for multiple comparisons (FWE Po0.05). Using a ROI approach, green tea extract increased activation in the DLPFC relative to a control condition (FWE Po0.001). This neural effect was related to green tea dosage. Green tea extract was not associated with any significant attenuation in regional activation relative to control condition. CONCLUSIONS: These data suggest that green tea extract may modulate brain activity in the DLPFC, a key area that mediates working memory processing in the human brain. Moreover, this is the first neuroimaging study implicating that functional neuroimaging methods provide a means of examining how green tea extract acts on the brain.

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·P-58 Power and sample size calculations: A review and computer program

Cited by 748 publications

References 0 publications

Subcutaneous versus Intraarticular Indwelling Closed Suction Drainage after TKA: A Randomized Controlled Trial

Subcutaneous versus Intraarticular Indwelling Closed Suction Drainage after TKA: A Randomized Controlled Trial

Restless legs syndrome does not affect 3-year mortality in hemodialysis patients

Neural effects of green tea extract on dorsolateral prefrontal cortex

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