Sample Size Calculations in Clinical Research

Chow, Shein‐Chung; Wang, Hansheng; Shao, Jun

doi:10.1201/9781584889830

Cited by 631 publications

(590 citation statements)

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“…Thus, 130 patients per arm were to be enrolled to have 80% power to detect a difference between the group proportions of −0.09 [11]. The proportion in norfloxacin group was assumed to be 0.12 under the null hypothesis and 0.03 under the alternative hypothesis.…”

Section: Methodsmentioning

confidence: 99%

The usefulness of antibiotic prophylaxis in invasive urodynamics in postmenopausal female subjects

Siracusano

Knez

Tiberio³

et al. 2008

Int Urogynecol J

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This study aims to define the usefulness of antibiotic prophylaxis of urinary tract infection (UTI) in postmenopausal female undergoing invasive urodynamics (IU). Two hundred sixty-two postmenopausal females underwent IU. Before urodynamics, all females were double blindly randomized in two age stratified groups. Group 1 (130 patients) received oral antibiotic prophylaxis with a single 400-mg dose of norfloxacin. Group 2 (132 patients) received norfloxacin placebo. Statistical analysis was performed by a chi (2) test to evaluate differences between groups for UTI incidence rate. Fifty-four patients of 262 (20.6%) resulted affected by UTI [24 of 130 subjects who received antibiotic prophylaxis (18.4%) and 30 of 132 subjects who received placebo (22.7%)]. There was no statically significant difference (P = 0.242) regarding UTI incidence rate between patients who received and those who did not received antibiotic prophylaxis. UTI incidence rate in postmenopausal women undergoing urodynamics is not affected by administration of antibiotic prophylaxis at the desired level of efficacy.

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Section: Methodsmentioning

confidence: 99%

The usefulness of antibiotic prophylaxis in invasive urodynamics in postmenopausal female subjects

Siracusano

Knez

Tiberio³

et al. 2008

Int Urogynecol J

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“…We examined these issues logically, mathematically, philosophically and from the perspective of evidence-based medicine. On the basis of the results on CAPRIE, CREDO trials and subgroups in CHARISMA trial [22,23] , we re-estimated their minimal sample sizes and their powers of the tests by employing three well-known statistical formulas as follows [24][25][26][27][28] . The formula of sample size calculation for hypothesis testing of two population proportions is: / c n n = [24] .…”

Section: Methodsmentioning

confidence: 99%

“…We, surprisingly found that the sample size in CAPRIE trial (19 185), fell far behind the requirements. Furthermore, we found that its power of the test (1-β) was only 33.70% [27,28] . Subjecting its minimal sample size to the well-known formula for sample size calculation for two-sample parallel design [26] , we obtained very similar results: The minimal sample size should be 84 968.…”

Section: Design Defects: Sample Sizes Too Small and Powers Too Lowmentioning

confidence: 99%

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Revaluation of clopidogrel: let the data speak for themselves

Liu

Fan-dian

Zeng

et al. 2010

J. Huazhong Univ. Sci. Technol. [Med. Sci.]

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Clopidogrel was believed to be superior to aspirin by the well-known CAPRIE trial. However, no other large clinical trials demonstrated the same results, but all focused on the combination use of clopidogrel with aspirin, and combination therapy in CREDO was called the "Emperor's New Clothes". However, no one overturned the results of these clinical trials by quantitatively analyzing them. We reviewed ten large-scale clinical trials about clopidogrel. On the basis of results of CAPRIE, CREDO and CHARISMA trials, we re-estimated their minimal sample sizes and their powers by three well-established statistical methodologies. From the results of CAPRIE, we inferred that the minimal sample size should be 85 086 or 84 968 but its power was only 30.70%. A huge gap existed. The same was also true of CREDO and CHARISMA trials. Moreover, in CAPRIE trial, 0 was included in the 95% confidence interval and 1 was included in the 95% confidence interval for the relative risk. There were some paradoxical data in CAPRIE trial. We are led to conclude that the results in CAPRIE, CREDO, and from the subgroup analysis in CHARISMA trials were questionable. These results failed to demonstrate that clopidogrel was superior to aspirin or that clopidogrel used in combination with aspirin was better than aspirin alone. The cost-effectiveness analyses by some previous studies were not reliable.

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“…1. Sample size for a crossover trial is generally calculated from the equation that is used for comparing means in the t test for unpaired samples [32,33]. To compute the sample size in this trial, power, allowable difference, variance, and superiority were assumed at 80%, 50 %, 1, and 0.1, respectively (free online computation at: http://www.…”

Section: Phase 1 Trial Of Lpr In Healthy Volunteersmentioning

confidence: 99%

In vitro anti-lithogenic activity of lime powder regimen (LPR) and the effect of LPR on urinary risk factors for kidney stone formation in healthy volunteers

et al. 2015

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Hypocitraturia, hypokaliuria, and increased oxidative stress are common lithogenic risk factors found in nephrolithiasis patients, especially in Thailand. We previously developed lime powder regimen (LPR), and demonstrated that LPR delivered citraturic, alkalinizing, and antioxidative effects in kidney stone patients. In this study, in vitro anti-lithogenic activity, in vivo acute toxicity, and crossover-designed phase 1 trial (in 13 healthy volunteers) of LPR were investigated. LPR inhibited the growth of calcium oxalate monohydrate (COM) crystals in dose-dependent manner, and inhibited the intracellular production of reactive oxygen species (ROS) in COM-treated HK-2 cells. LPR did not significantly alter viability of HK-2 cells. No acute toxicity was detected in mice orally fed with LPR (10 g/kg). No adverse effect and complaint of LPR ingestion (5 g/dose) were observed in the tested volunteers. Plasma citrate was elevated at 30 min after LPR load, which was higher than the water load control. Plasma potassium was significantly elevated at 30 min after LPR load and remained high for 2 h, and at 2 h, it was significantly higher than the water load. Urinary citrate was significantly increased at 1 h after LPR load and remained high for 2 h, and at 2 h, it was significantly higher than the water load. Urinary potassium was significantly increased at 1 h after LPR load and remained high for 3 h, and its levels at 1, 2, and 3 h were significantly higher than the water load. Urinary total antioxidant status was significantly increased at 2 h after LPR load. In conclusion, LPR had an inhibitory effect on COM growth and exerted as antioxidant to attenuate ROS production in the COM-treated renal tubular cells. LPR provided citraturic, kaliuric, and antioxidative responses in healthy individuals without any adverse events. This suggests that LPR is well tolerated and safe for daily consumption.

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Sample Size Calculations in Clinical Research

Cited by 631 publications

References 0 publications

The usefulness of antibiotic prophylaxis in invasive urodynamics in postmenopausal female subjects

The usefulness of antibiotic prophylaxis in invasive urodynamics in postmenopausal female subjects

Revaluation of clopidogrel: let the data speak for themselves

In vitro anti-lithogenic activity of lime powder regimen (LPR) and the effect of LPR on urinary risk factors for kidney stone formation in healthy volunteers

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