scholarly journals Sample Size Estimates for Clinical Trials of Vasospasm in Subarachnoid Hemorrhage

Stroke ◽  
2009 ◽  
Vol 40 (7) ◽  
pp. 2362-2367 ◽  
Author(s):  
Kurt T. Kreiter ◽  
Stephan A. Mayer ◽  
George Howard ◽  
Volker Knappertz ◽  
Don Ilodigwe ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Subarachnoid Hemorrhage ◽  
Sample Size ◽  
Size Estimates

Competing event risk stratification may improve the design and efficiency of clinical trials: Secondary analysis of SWOG 8794.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 6121-6121
Author(s):  
Brent Shane Rose ◽  
Kaveh Zakeri ◽  
Sachin Gulaya ◽  
Anthony Victor D'Amico ◽  
Loren K. Mell
Keyword(s):  
Clinical Trials ◽  
High Risk ◽  
Sample Size ◽  
Risk Score ◽  
Performance Status ◽  
Risk Scores ◽  
Adjuvant Radiation ◽  
Type I ◽  
Event Risk ◽  
Size Estimates

6121 Background: Efficiency of clinical trials may be improved by stratifying according to competing event risk. We aimed to test whether effect and sample size estimates would be altered when adjusting for competing event risk, using data from the SWOG 8794 trial of adjuvant radiation therapy (RT) for high-risk post-operative prostate cancer. Methods: The primary outcome was metastasis-free survival (MFS), defined as time to first occurrence of metastasis or death from any cause (i.e., competing mortality (CM)). We developed separate risk scores for time to metastasis and CM using backward stepwise competing risks regression. Risk factors for metastasis were PSA, Gleason score, and seminal vesicle invasion, and for CM were age, performance status, and Charlson comorbidity index. Treatment effects were estimated using Cox models adjusted for risk scores. We identified an enriched subgroup of 75 patients at high risk of metastasis and low risk of CM, based on risk score cutoffs. Sample size estimates assumed type I and II error of 0.10 and 0.20, and accrual and follow-up times of 6 and 6 years. Results: The mean CM risk score was significantly lower in the RT vs. control arm (p=0.001). The effect of RT on MFS (HR 0.70; 95% CI, 0.53-0.92; p=0.010) was attenuated when controlling for metastasis and CM risk (HR 0.76; 95% CI, 0.58-1.00; p=0.049). The hazard for CM was reduced by RT (HR 0.82; 95% CI, 0.59-1.14; p=0.24), but this effect was attenuated when controlling for CM risk (HR 0.94; 95% CI, 0.67-1.31; p=0.71). In contrast, there was no difference in the adjusted and unadjusted HRs for metastasis (0.50; 95% CI, 0.31-0.81; p=0.005 and 0.49; 95% CI, 0.30-0.81; p=0.005). Compared to the whole cohort, the enriched subgroup had the same baseline 10-year incidence of MFS (40%; 95% CI 22-57%), but a higher incidence of metastasis (30% (95% CI, 15-47%) vs. 20% (95% CI, 15-26%)). A randomized trial in an enriched population could have achieved 80% power with 44% less patients (313 vs. 709 patients, respectively), due to the differing event composition. Conclusions: Stratification based on competing event risk may improve the design and efficiency of clinical trials. These findings should be externally validated.

scholarly journals Sample Size Requirements of Glaucoma Clinical Trials When Using Combined Optical Coherence Tomography and Visual Field Endpoints

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Zhichao Wu ◽  
Felipe A. Medeiros
Keyword(s):  
Clinical Trials ◽  
Optical Coherence Tomography ◽  
Visual Field ◽  
Sample Size ◽  
Treatment Effect ◽  
Optical Coherence ◽  
Non Invasive ◽  
Combined Use ◽  
Oct Imaging ◽  
Size Estimates

AbstractGlaucoma clinical trials using visual field (VF) endpoints currently require large sample sizes because of the slowly-progressive nature of this disease. We sought to examine whether the combined use of VF testing and non-invasive optical coherence tomography (OCT) imaging of the neuroretinal tissue could improve the feasibility of such trials. To examine this, we included 192 eyes of 121 glaucoma participants seen at ≥5 visits over a 2-year period to extract real-world estimates of the rates of change and variability of VF and OCT imaging measurements for computer simulations to obtain sample size estimates. We observed that the combined use of VF and OCT endpoints led to a 31–33% reduction in sample size requirements compared to using VF endpoints alone for various treatment effect sizes. For example, 189 participants would be required per group to detect a 30% treatment effect with 90% power with combined VF and OCT endpoints, whilst 276 and 285 participants would be required when using VF and OCT endpoints alone respectively. The combined use of OCT and VF endpoints thus has the potential to effectively improve the feasibility of future glaucoma clinical trials.

scholarly journals Unbiased tensor-based morphometry: Improved robustness and sample size estimates for Alzheimer's disease clinical trials

NeuroImage ◽  
2013 ◽  
Vol 66 ◽  
pp. 648-661 ◽  
Author(s):  
Xue Hua ◽  
Derrek P. Hibar ◽  
Christopher R.K. Ching ◽  
Christina P. Boyle ◽  
Priya Rajagopalan ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Clinical Trials ◽  
Sample Size ◽  
Size Estimates

THE CONDUCT OF CLINICAL TRIALS OF SUBSTANCES PROPOSED FOR THE NUTRITION OF INFANTS AND CHILDREN

PEDIATRICS ◽  
1957 ◽  
Vol 19 (4) ◽  
pp. 694-700
Author(s):  
Charles U. Lowe ◽  
Vivian Pessin
Keyword(s):  
Clinical Trials ◽  
Design Of Experiments ◽  
Sample Size ◽  
Dietary Supplement ◽  
Human Subjects ◽  
Animal Experiments ◽  
Normal Subjects ◽  
Heterogeneous Population ◽  
The People ◽  
Size Estimates

ANIMAL experiments may offer evidence of the value of a substance for human nutrition, but only well-conducted clinical trials can result in a verdict. Unless substances are tested on human subjects, judgment should be withheld. Though the design of experiments varies, certain general principles pertain to all experimentation; in addition, special considerations apply in the field of nutrition. The outline which follows presents some of these principles and considerations and should be useful to those conducting clinical trials. A statement of specific objectives should be prepared as the first step. In order to estimate the necessary sample size, estimates of expected results must be obtained, or deduced, either from the literature or from a pilot experiment. All possible sources of bias, such as age, sex, race, etc. should be listed in advance and considered in planning the study. Decisions must also be made concerning the following: 1) population for which the results will be relevant; 2) controls; 3)criteria for judging results; 4) sample size and duration of study; 5) form of reporting results. Whenever possible the people who give treatments and make measurements should be unable to distinguish between the study and the control subjects. I. POPULATION The type of population for which the conclusion is intended will determine the choice of subjects. For example the value of a foodstuff for all infants should be studied in subjects from a heterogeneous population. Alternatively, a dietary supplement for treating deficiency must be assayed in deficient subjects. Such a supplement would probably produce no signficant changes in normal subjects but even if it did the results would not necessarily apply to treatment of deficiency.

Planning the Size of Clinical Trials with Allowance for Patient Noncompliance

1990 ◽  
Vol 29 (03) ◽  
pp. 243-246 ◽  
Author(s):  
M. A. A. Moussa
Keyword(s):  
Clinical Trial ◽  
Clinical Trials ◽  
Sample Size ◽  
Event Rate ◽  
Survival Functions ◽  
Time Intervals ◽  
Patient Noncompliance ◽  
Event Rates ◽  
Larger Sample

AbstractVarious approaches are considered for adjustment of clinical trial size for patient noncompliance. Such approaches either model the effect of noncompliance through comparison of two survival distributions or two simple proportions. Models that allow for variation of noncompliance and event rates between time intervals are also considered. The approach that models the noncompliance adjustment on the basis of survival functions is conservative and hence requires larger sample size. The model to be selected for noncompliance adjustment depends upon available estimates of noncompliance and event rate patterns.

scholarly journals Do patient characteristics matter when calculating sample size for eczema clinical trials?

2021 ◽  
Author(s):  
L. Howells ◽  
S. Gran ◽  
J. R. Chalmers ◽  
B. Stuart ◽  
M. Santer ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Sample Size ◽  
Patient Characteristics

scholarly journals Stereotactic cisternal lavage in patients with aneurysmal subarachnoid hemorrhage with urokinase and nimodipine for the prevention of secondary brain injury (SPLASH): study protocol for a randomized controlled trial

Trials ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Roland Roelz ◽  
Fabian Schubach ◽  
Volker A. Coenen ◽  
Carolin Jenkner ◽  
Christian Scheiwe ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Subarachnoid Hemorrhage ◽  
Brain Injury ◽  
Neurological Outcome ◽  
Aneurysmal Subarachnoid Hemorrhage ◽  
Standard Of Care ◽  
Secondary Brain Injury ◽  
Ringer’S Solution ◽  
Randomized Controlled ◽  
Therapy Protocol

Abstract Background Delayed cerebral infarction (DCI) is a major cause of death and poor neurological outcome in patients with aneurysmal subarachnoid hemorrhage (aSAH). Direct intrathecal therapies with fibrinolytic and spasmolytic drugs have appeared promising in clinical trials. However, access to the subarachnoid space for intrathecal drug administration is an unsolved problem so far, especially in patients with endovascular aneurysm securing. We investigate a therapy protocol based on stereotactic catheter ventriculocisternostomy (STX-VCS), a new approach to overcome this problem. The primary objective of this study is to assess whether cisternal lavage with urokinase, nimodipine, and Ringer’s solution administered via a stereotactically implanted catheter into the basal cisterns (= investigational treatment (IT)) is safe and improves neurological outcome in patients with aSAH. Methods This is a randomized, controlled, parallel-group, open-label phase II trial. Fifty-four patients with severe aSAH (WFNS grade ≥ 3) will be enrolled at one academic tertiary care center in Southern Germany. Patients will be randomized at a ratio of 1:1 to receive either standard of care only or standard of care plus the IT. The primary endpoint is the proportion of subjects with a favorable outcome on the Modified Rankin Scale (defined as mRS 0–3) at 6 months after aSAH. Further clinical and surrogate outcome parameters are defined as secondary endpoints. Discussion New approaches for the prevention and therapy of secondary brain injury in patients with aSAH are urgently needed. We propose this RCT to assess the clinical safety and efficacy of a novel therapy protocol for intrathecal administration of urokinase, nimodipine, and Ringer’s solution. Trial registration Deutsches Register Klinischer Studien (German Clinical Trials Register), DRKS00015645. Registered on 8 May 2019

P1-410: SAMPLE SIZE ESTIMATES FOR SECONDARY PREVENTION STUDIES USING REGIONAL ATROPHY RATES

2006 ◽  
Vol 14 (7S_Part_8) ◽  
pp. P461-P462
Author(s):  
David M. Cash ◽  
Thomas Veale ◽  
Teresa Poole ◽  
Marc Modat ◽  
Erika Molteni ◽  
...  
Keyword(s):  
Secondary Prevention ◽  
Sample Size ◽  
Prevention Studies ◽  
Size Estimates
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