Sample size re-estimation in an on-going NIH-sponsored clinical trial: the secondary prevention of small subcortical strokes experience.
نویسندگان
چکیده
BACKGROUND AND PURPOSE When planning clinical trials, decisions regarding sample size are often based on educated guesses of parameters, which may in fact prove to be over- or under-estimates. For example, after initiation of the SPS3 study, published data indicated that the recurrent stroke rates might be lower than initially planned for the study. Failure to account for this could result in an under-powered study. Thus, we performed a sample size re-estimation, and describe the experience herein. METHODS We evaluated different scenarios based on a re-estimated overall event rate, including increasing the sample size and increasing the follow-up time, to determine their impact on both type I error and the power to detect the initially planned treatment difference. RESULTS We found that by increasing the sample size from 2500 to 3000 and by following the patients for one year after the end of recruitment, we would maintain our planned type I error rate, and increase the power to detect the prespecified clinically meaningful difference to between 67% and 87%, depending on the rate of recruitment. CONCLUSIONS We successfully implemented this unplanned design modification in the SPS3 study, in order to allow for sufficient power to detect the planned treatment differences. CLINICAL TRIALS REGISTRATION INFORMATION Clinical Trials Registration - http://clinicaltrials.gov/show/NCT00059306. Unique identifier: NCT00059306.
منابع مشابه
The Secondary Prevention of Small Subcortical Strokes (SPS3) study.
BACKGROUND Small subcortical strokes, also known as lacunar strokes, comprise more than 25% of brain infarcts, and the underlying vasculopathy is the most common cause of vascular cognitive impairment. How to optimally prevent stroke recurrence and cognitive decline in S3 patients is unclear. The aim of the Secondary Prevention of Small Subcortical Strokes study (Trial registration: NCT00059306...
متن کاملReliability and validity of blood pressure measurement in the Secondary Prevention of Small Subcortical Strokes study.
RATIONALE The Secondary Prevention of Small Subcortical Strokes study is a multicenter, international trial funded by the National Institutes of Health testing the role of lowering systolic blood pressure to <130 mmHg in the prevention of stroke recurrence and cognitive decline in patients with recent symptomatic small subcortical stroke. Reliable and unbiased blood pressure measurement is crit...
متن کاملClinical correlates of infarct shape and volume in lacunar strokes: the Secondary Prevention of Small Subcortical Strokes trial.
BACKGROUND AND PURPOSE Infarct size and location are thought to correlate with different mechanisms of lacunar infarcts. We examined the relationship between the size and shape of lacunar infarcts and vascular risk factors and outcomes. METHODS We studied 1679 participants in the Secondary Prevention of Small Subcortical Stroke trial with a lacunar infarct visualized on diffusion-weighted ima...
متن کاملLetter by Mezue et al Regarding Article, "Effect of Intensive Versus Usual Blood Pressure Control on Kidney Function Among Individuals With Prior Lacunar Stroke: A Post Hoc Analysis of the Secondary Prevention of Small Subcortical Strokes (SPS3) Randomized Trial".
متن کامل
Clinical Correlates of Infarct Shape and Volume in Lacunar Strokes
The volume of acute ischemic infarcts has been shown to correlate with stroke severity and functional outcomes in all subtypes of ischemic stroke. In patients with lacunar stroke, infarct size in conjunction with infarct location has been proposed to distinguish this subtype from other forms of subcortical ischemic stroke. Most lacunar infarcts are caused by occlusion of the penetrating small v...
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ورودعنوان ژورنال:
- Contemporary clinical trials
دوره 33 5 شماره
صفحات -
تاریخ انتشار 2012