Sample Size Tables for Clinical Studies

Machin, David

doi:10.1002/9781444300710

Cited by 747 publications

(720 citation statements)

References 6 publications

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“…Using previous reports of the frequency of symptomatic hypoglycaemia in insulin-treated type 2 diabetes [2], we assumed that 60% of type 2 diabetic patients treated with sulfonylureas would experience at least one episode during CGMS monitoring. To show that the difference in the proportion of hypoglycaemic incidents experienced between the two groups of interest was within 15%, and assuming four ordered categories for the event data (0, 1, 2, and more than two events), the study required 120 patients for the two main groups of interest to achieve 80% power at a one-sided significance level of 5% [11].…”

Section: Discussionmentioning

confidence: 99%

Risk of hypoglycaemia in types 1 and 2 diabetes: effects of treatment modalities and their duration

2007

Diabetologia

757

259

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Aims/hypothesis We explored the epidemiology of hypoglycaemia in individuals with insulin-treated diabetes by testing the hypothesis that diabetes type and duration of insulin treatment influence the risk of hypoglycaemia. Materials and methods This was an observational study over 9-12 months in six UK secondary care diabetes centres. Altogether 383 patients were involved. Patients were divided into the following three treatment groups for type 2 diabetes: (1) sulfonylureas, (2) insulin for <2 years and (3) insulin for >5 years, and into two treatment groups for type 1 diabetes, namely <5 years disease duration and >15 years disease duration. Self-reported (mild and severe) and biochemical episodes (interstitial glucose <2.2 mmol/l using continuous glucose monitoring) were recorded. Results Mild hypoglycaemia in type 2 diabetic patients on insulin for <2 years was less frequent than in type 1 patients with <5 years disease duration (mean rate: 4 vs 36 episodes per subject-year, p<0.001). In type 2 diabetic patients treated with sulfonylureas or insulin for <2 years, no differences were observed in the proportion experiencing severe hypoglycaemia (7 vs 7%, difference 0 [95% CI: −7to 9%]), mild symptomatic (39 vs 51%, difference 12 [−3 to 25%]) or interstitial glucose <2.2 mol/l (22 vs 20%, difference 2 [−13 to 10%]). Severe hypoglycaemia rates were comparable in patients with type 2 diabetes on sulfonylureas or insulin < 2 years (0.1 and 0.2 episodes per subject-year) and far less frequent than in type 1 diabetes (<5 years group, 1.1; >15 years group, 3.2. episodes per subject-year). Conclusions/interpretation During early insulin use in type 2 diabetes, the frequency of hypoglycaemia is generally equivalent to that observed in patients treated with sulfonylureas and considerably lower than during the first 5 years of treatment in type 1 diabetes.

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Section: Discussionmentioning

confidence: 99%

Risk of hypoglycaemia in types 1 and 2 diabetes: effects of treatment modalities and their duration

2007

Diabetologia

757

259

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“…A sample size greater than or equal to 123 allowed detection of correlations superior or equal to 0.25, based on an alpha significance level of 5% and power of 80% [45]. Independent variables whose bivariate test results had a P value lower than 0.05 were retained for stepwise multiple regression analysis.…”

Section: Discussionmentioning

confidence: 99%

“…The study was cross-sectional, and the sample size was not sufficient (n = 155) to detect correlations smaller than 0.25 for a P value of 0.05 and power of 80% [45] or evaluate the stability of our models. Finally, some items of the measurement tools were similar and might partly explain some relationships, especially for social participation and the environment.…”

Section: Study Limitations and Strengthsmentioning

confidence: 99%

Accomplishment level and satisfaction with social participation of older adults: association with quality of life and best correlates

2010

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Purpose-This study aimed to (1) explore whether quality of life (QOL) is more associated with satisfaction with social participation (SP) than with level of accomplishment in SP and (2) examine respective correlates of accomplishment level and satisfaction with SP.Methods-A cross-sectional design was used with a convenience sample of 155 older adults (mean age = 73.7; 60% women) having various levels of activity limitations. Accomplishment level and satisfaction with SP (dependent variables) were estimated with the social roles items of the assessment of life habits. Potential correlates were human functioning components.Results-Correlations between QOL and accomplishment level and satisfaction with SP did not differ (P = 0.71). However, best correlates of accomplishment level and satisfaction with SP were different. Higher accomplishment level of SP was best explained by younger age, activity level perceived as stable, no recent stressing event, better well-being, higher activity level, and fewer obstacles in "Physical environment and accessibility" (R 2 = 0.79). Greater satisfaction with SP was best explained by activity level perceived as stable, better self-perceived health, better wellbeing, higher activity level, and more facilitators in "Social support and attitudes" (R 2 = 0.51).Conclusion-With some exceptions, these best correlates may be positively modified and thus warrant special attention in rehabilitation interventions.

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“…Based on previously published data by Tuncok et al, a power calculation suggested that 80% power could be achieved with five animals in each group if an average difference in mean arterial pressure (MAP) was 10 mmHg at the completion of the protocol, assuming standard deviations of 5 mmHg (5.1% of average baseline MAP of 103 mmHg) [19]. With standard deviations of 10 mmHg, a difference in MAP of 20 mmHg would need to be seen [20,21]. However, in that study, both control and treatment groups had improvement in MAP.…”

Section: Methodsmentioning

confidence: 99%

Survival of Verapamil-Poisoned Rats Treated with Triiodothyronine

et al. 2010

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Life-threatening toxicity due to calcium channel blocker ingestion is commonly encountered by emergency medicine physicians and toxicologists. Despite a vast array of research on its treatment, results have proven inconsistent. The goal of this study is to evaluate potential vasopressor effects of triiodothyronine (T3) in rats poisoned with verapamil. Following anesthesia and intubation, ten Sprague-Dawley rats were given intravenous verapamil infusion of 10 mg/kg/h. This dose was titrated until a mean arterial pressure (MAP) of 50-55 mmHg was achieved and maintained for a period of at least 5 min. The verapamil infusion was then maintained at that rate. Five rats were randomized to receive a T3 bolus of 0.4 mcg/kg preceding an infusion of 1.5 mcg/kg/day which was doubled every 2 min until any of the following endpoints: systolic blood pressure of 100 mmHg, an elapsed time of 60 min, or death. The other five received an equal volume of normal saline solution. The primary outcome measure was survival with secondary outcomes of MAP and heart rate. The T3 group did have a slightly longer, yet not statistically significant, average time to cessation of electrical activity-30.0±14.4 min versus 23.8±9.5 min in the placebo group. Average MAP decreased nearly identically in the two groups. Heart rates were not reliable indicators of toxicity in this rat model as there was little decrease until immediately prior to death in most animals. Despite significant variability in toxicity among individual animals, no statistically significant difference in survival time, heart rate, or MAP was found between groups treated with T3 and those receiving saline.

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Sample Size Tables for Clinical Studies

Cited by 747 publications

References 6 publications

Risk of hypoglycaemia in types 1 and 2 diabetes: effects of treatment modalities and their duration

Risk of hypoglycaemia in types 1 and 2 diabetes: effects of treatment modalities and their duration

Accomplishment level and satisfaction with social participation of older adults: association with quality of life and best correlates

Survival of Verapamil-Poisoned Rats Treated with Triiodothyronine

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