A simple sample size formula for analysis of covariance in randomized clinical trials

Borm, George F.; Fransen, Jaap; Lemmens, W.A.J.G.

doi:10.1016/j.jclinepi.2007.02.006

Cited by 450 publications

(405 citation statements)

References 14 publications

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“…Differences in week 8 outcomes between the groups were assessed by analysis of covariance (ANCOVA), using the pretest results as the covariate, in a complete case analysis. ANCOVA has been recommended to increase the precision of estimates and the statistical power while also reducing the sample size requirements [25][26]. As stated by White et al, complete case analysis is appropriate for randomized trials with pretest-posttest designs [27].…”

Section: Discussionmentioning

confidence: 99%

Efficacy of simple integrated group rehabilitation program for patients with knee osteoarthritis: Single-blind randomized controlled trial

et al. 2015

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Abstract-We investigated the role of an evidence-based integrated group rehabilitation program on the treatment of patients with knee osteoarthritis (KOA). This was a two-group, randomized controlled, 8 wk trial with 41 patients with moderate to very severe KOA. Patients were assigned to an intervention group (IG) or control group (CG). After both groups had received a self-management education program, IG participants underwent a rehabilitation program, including educational aspects about KOA followed by exercises. CG participants received only general health orientation about KOA during this period. The outcome measures were the Lequesne algofunctional index; 36-Item Short Form Health Survey (SF-36); and chair-stand, sit-and-reach, timed up-and-go, and 6-minute walk tests. Analysis of covariance revealed significant postintervention improvements of IG participants compared with CG participants (p < 0.05) on Lequesne total score and pain and function subdomains; SF-36 physical function, role physical, bodily pain, general health, vitality, and role emotional subdomains; and performance assessed by chair-stand, timed up-and-go, and 6-minute walk tests. Focusing on the primary outcome (Lequesne total score), the mean +/-standard deviation after 8 wk was 5.50 +/-2.98 for the IG and 7.87 +/-3. https://clinicaltrials.gov/ct2/show/ NCT01850862?term=NCT01850862&rank=1

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Section: Discussionmentioning

confidence: 99%

Efficacy of simple integrated group rehabilitation program for patients with knee osteoarthritis: Single-blind randomized controlled trial

et al. 2015

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“…Using an a = 0.05 level of significance and including specimens from both regions of the femur, the sample size (n = 12 smallest sample size) had a power of 0.99 to detect a difference in yield strain of 1.72*10 À3 strain (20% of the expected mean value) with analysis of variance. Using the approximation of statistical power for analysis of covariance proposed by Borm and colleagues [9], the smallest sample size had a power of 0.99 to observe a 20% decrease in the relationship between bone volume fraction and either Young's modulus or yield strength. Proximal femur specimens had an average height to diameter ratio of approximately 2.3:1 (length 20.73 ± 2.67 mm; diameter 8.15 ± 0.06 mm, mean ± SD); distal femur specimens had an average height to diameter ratio of approximately 2.5:1 (length 18.87 ± 1.40 mm, diameter 8.24 ± 0.03 mm).…”

Section: Methodsmentioning

confidence: 99%

Irradiation Does Not Modify Mechanical Properties of Cancellous Bone Under Compression

Hernandez

Ramsey

Dux

et al. 2012

Clinical Orthopaedics &Amp; Related Research

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Background Gamma radiation sterilization can make cortical bone allograft more brittle, but whether it influences mechanical properties and propensity to form microscopic cracks in structurally intact cancellous bone allograft is unknown. Questions/purposes We therefore determined the effects of gamma radiation sterilization on structurally intact cancellous bone mechanical properties and damage formation in both low-and high-density femoral cancellous bone (volume fraction 9%-44%). Methods We studied 26 cancellous bone cores from the proximal and distal femurs of 10 human female cadavers (49-82 years of age) submitted to a single compressive load beyond yield. Mechanical properties and the formation of microscopic cracks and other tissue damage (identified through fluorochrome staining) were compared between irradiated and control specimens. Results We observed no alterations in mechanical properties with gamma radiation sterilization after taking into account variation in specimen porosity. No differences in microscopic tissue damage were observed between the groups. Conclusions Although gamma radiation sterilization influences the mechanical properties and failure processes in cortical bone, it does not appear to influence the performance of cancellous bone under uniaxial loading. Clinical Relevance Our observations support the use of radiation sterilization on structurally intact cancellous bone allograft.

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“…This type of analysis accounts for regression to the mean and raises power of the analyses (Borm et al, 2007;Kenward and Roger, 1997).…”

Section: Statistical Analysesmentioning

confidence: 99%

Effects of online intervention for depression on mood and positive symptoms in schizophrenia

Moritz

Schröder

Klein

et al. 2016

Schizophrenia Research

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A simple sample size formula for analysis of covariance in randomized clinical trials

Cited by 450 publications

References 14 publications

Efficacy of simple integrated group rehabilitation program for patients with knee osteoarthritis: Single-blind randomized controlled trial

Efficacy of simple integrated group rehabilitation program for patients with knee osteoarthritis: Single-blind randomized controlled trial

Irradiation Does Not Modify Mechanical Properties of Cancellous Bone Under Compression

Effects of online intervention for depression on mood and positive symptoms in schizophrenia

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