Randomized Controlled Trials 5: Determining the Sample Size and Power for Clinical Trials and Cohort Studies

2015 ◽  
pp. 225-247 ◽  
Author(s):  
Tom Greene
Keyword(s):  
Clinical Trials ◽  
Cohort Studies ◽  
Randomized Controlled Trials ◽  
Sample Size ◽  
Controlled Trials ◽  
Randomized Controlled

scholarly journals Detection of significant antiviral drug effects on COVID-19 with reasonable sample sizes in randomized controlled trials: A modeling study

PLoS Medicine ◽  
2021 ◽  
Vol 18 (7) ◽  
pp. e1003660
Author(s):  
Shoya Iwanami ◽  
Keisuke Ejima ◽  
Kwang Su Kim ◽  
Koji Noshita ◽  
Yasuhisa Fujita ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Viral Load ◽  
Randomized Controlled Trials ◽  
Sample Size ◽  
Antiviral Effect ◽  
Controlled Trials ◽  
Virus Dynamics ◽  
Viral Dynamics ◽  
Dynamics Model ◽  
Randomized Controlled

Background Development of an effective antiviral drug for Coronavirus Disease 2019 (COVID-19) is a global health priority. Although several candidate drugs have been identified through in vitro and in vivo models, consistent and compelling evidence from clinical studies is limited. The lack of evidence from clinical trials may stem in part from the imperfect design of the trials. We investigated how clinical trials for antivirals need to be designed, especially focusing on the sample size in randomized controlled trials. Methods and findings A modeling study was conducted to help understand the reasons behind inconsistent clinical trial findings and to design better clinical trials. We first analyzed longitudinal viral load data for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) without antiviral treatment by use of a within-host virus dynamics model. The fitted viral load was categorized into 3 different groups by a clustering approach. Comparison of the estimated parameters showed that the 3 distinct groups were characterized by different virus decay rates (p-value < 0.001). The mean decay rates were 1.17 d−1 (95% CI: 1.06 to 1.27 d−1), 0.777 d−1 (0.716 to 0.838 d−1), and 0.450 d−1 (0.378 to 0.522 d−1) for the 3 groups, respectively. Such heterogeneity in virus dynamics could be a confounding variable if it is associated with treatment allocation in compassionate use programs (i.e., observational studies). Subsequently, we mimicked randomized controlled trials of antivirals by simulation. An antiviral effect causing a 95% to 99% reduction in viral replication was added to the model. To be realistic, we assumed that randomization and treatment are initiated with some time lag after symptom onset. Using the duration of virus shedding as an outcome, the sample size to detect a statistically significant mean difference between the treatment and placebo groups (1:1 allocation) was 13,603 and 11,670 (when the antiviral effect was 95% and 99%, respectively) per group if all patients are enrolled regardless of timing of randomization. The sample size was reduced to 584 and 458 (when the antiviral effect was 95% and 99%, respectively) if only patients who are treated within 1 day of symptom onset are enrolled. We confirmed the sample size was similarly reduced when using cumulative viral load in log scale as an outcome. We used a conventional virus dynamics model, which may not fully reflect the detailed mechanisms of viral dynamics of SARS-CoV-2. The model needs to be calibrated in terms of both parameter settings and model structure, which would yield more reliable sample size calculation. Conclusions In this study, we found that estimated association in observational studies can be biased due to large heterogeneity in viral dynamics among infected individuals, and statistically significant effect in randomized controlled trials may be difficult to be detected due to small sample size. The sample size can be dramatically reduced by recruiting patients immediately after developing symptoms. We believe this is the first study investigated the study design of clinical trials for antiviral treatment using the viral dynamics model.

scholarly journals Enhancing Patient Centricity and Advancing Innovation in Clinical Research with Virtual Randomized Clinical Trials (vRCTs)

Diagnostics ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 151
Author(s):  
Raphael A. Yaakov ◽  
Özgür Güler ◽  
Tim Mayhugh ◽  
Thomas E. Serena
Keyword(s):  
Clinical Trials ◽  
Randomized Controlled Trials ◽  
Randomized Clinical Trials ◽  
Regulatory Compliance ◽  
Small Sample ◽  
Controlled Trials ◽  
Holistic View ◽  
Health Crisis ◽  
Randomized Controlled ◽  
Healthcare Needs

The current public health crisis has highlighted the need to accelerate healthcare innovation. Despite unwavering levels of cooperation among academia, industry, and policy makers, it can still take years to bring a life-saving product to market. There are some obvious limitations, including lack of blinding or masking and small sample size, which render the results less applicable to the real world. Traditional randomized controlled trials (RCTs) are lengthy, expensive, and have a low success rate. There is a growing acknowledgement that the current process no longer fully meets the growing healthcare needs. Advances in technology coupled with proliferation of telehealth modalities, sensors, wearable and connected devices have paved the way for a new paradigm. Virtual randomized controlled trials (vRCTs) have the potential to drastically shorten the clinical trial cycle while maximizing patient-centricity, compliance, and recruitment. This new approach can inform clinical trials in real time and with a holistic view of a patient’s health. This paper provides an overview of virtual clinical trials, addressing critical issues, including regulatory compliance, data security, privacy, and ownership.

The effect of almond intake on lipid profile: a systematic review and meta-analysis of randomized controlled trials

2021 ◽  
Author(s):  
Omid Asbaghi ◽  
Vihan Moodi ◽  
Amir Hadi ◽  
Elham Eslampour ◽  
Mina Shirinbakhshmasoleh ◽  
...  
Keyword(s):  
Systematic Review ◽  
Clinical Trials ◽  
Randomized Controlled Trials ◽  
Lipid Profile ◽  
Meta Analysis ◽  
Controlled Trials ◽  
Randomized Controlled

A number of clinical trials have examined the effect of almond intake on the lipid profile in recent years; however, the results remain equivocal.

Trends in randomized controlled trials in ENT: a 30-year review

1997 ◽  
Vol 111 (7) ◽  
pp. 611-613 ◽  
Author(s):  
K. W. Ah-See ◽  
N. C. Molony ◽  
A. G. D. Maran
Keyword(s):  
Clinical Trials ◽  
Clinical Practice ◽  
Randomized Controlled Trials ◽  
Gold Standard ◽  
Controlled Trials ◽  
Evidence Based ◽  
Controlled Clinical Trials ◽  
Medline Search ◽  
Randomized Controlled Clinical Trials ◽  
Randomized Controlled

AbstractThere is a growth in the demand for clinical practice to be evidence based. Recent years have seen a rise in the number of randomized controlled clinical trials (RCTS). Such trials while acknowledged as the gold standard for evidence can be difficult to perform in surgical specialities. We have recently identified a low proportion of RCTS in the otolaryngology literature. Our aim was to identify any trend in the number of published RCTS within the ENT literature over a 30-year period and to identify which areas of our speciality lend themselves to this form of study design. A Medline search of 10 prominent journals published between 1966 and 1995 was performed. Two hundred and ninety-six RCTS were identified. Only five were published before 1980. Two hundred (71 per cent) of RCTS were in the areas of otology and rhinology. An encouraging trend is seen in RCTS within ENT literature.

scholarly journals MANAGEMENT OF ENDOCRINE DISEASE: Effects of telecare intervention on glycemic control in type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials

2015 ◽  
Vol 172 (3) ◽  
pp. R93-R101 ◽  
Author(s):  
Zhenru Huang ◽  
Hong Tao ◽  
Qingdong Meng ◽  
Long Jing
Keyword(s):  
Type 2 Diabetes ◽  
Glycemic Control ◽  
Randomized Controlled Trials ◽  
Sample Size ◽  
Plasma Glucose ◽  
Small Sample ◽  
Cochrane Library ◽  
Controlled Trials ◽  
Randomized Controlled

ObjectiveTo review the published literature on the effects of telecare intervention in patients with type 2 diabetes and inadequate glycemic control.Design and methodsA review of randomized controlled trials on telecare intervention in patients with type 2 diabetes, and a search of electronic databases such as The Cochrane Library, PubMed, EBSCO, CINAHL, Science Direct, Journal of Telemedicine and Telecare, and China National Knowledge Infrastructure (CNKI), were conducted from December 8 to 16, 2013. Two evaluators independently selected and reviewed the eligible studies. Changes in HbA1c, fasting plasma glucose (FPG), post-prandial plasma glucose (PPG), BMI, and body weight were analyzed.ResultsAn analysis of 18 studies with 3798 subjects revealed that telecare significantly improved the management of diabetes. Mean HbA1c values were reduced by −0.54 (95% CI, −0.75 to −0.34; P<0.05), mean FPG levels by −9.00 mg/dl (95% CI, −17.36 to −0.64; P=0.03), and mean PPG levels reduced by −52.86 mg/dl (95% CI, −77.13 to −28.58; P<0.05) when compared with the group receiving standard care. Meta-regression and subgroup analyses indicated that study location, sample size, and treatment-monitoring techniques were the sources of heterogeneity.ConclusionsPatients monitored by telecare showed significant improvement in glycemic control in type 2 diabetes when compared with those monitored by routine follow-up. Significant reduction in HbA1c levels was associated with Asian populations, small sample size, and telecare, and with those patients with baseline HbA1c greater than 8.0%.

scholarly journals A Review of Marital Intimacy-Enhancing Interventions among Married Individuals

2015 ◽  
Vol 8 (8) ◽  
pp. 74 ◽  
Author(s):  
Maryam Kardan-Souraki ◽  
Zeinab Hamzehgardeshi ◽  
Ismail Asadpour ◽  
Reza Ali Mohammadpour ◽  
Soghra Khani
Keyword(s):  
Clinical Trials ◽  
Randomized Controlled Trials ◽  
Cochrane Library ◽  
Controlled Trials ◽  
Main Concern ◽  
Care Providers ◽  
Marital Intimacy ◽  
Randomized Controlled ◽  
The Impact

<p><strong>BACKGROUND:</strong> Lack of intimacy is currently the main concern rather than main concern of the experts in psychology and counseling. It is considered as one of the most important causes for divorce and as such to improve marital intimacy a great number of interventions have been proposed in the literature. Intimacy training and counseling make the couples take effective and successful steps to increase marital intimacy. No study has reviewed the interventions promoting marital intimacy after marriage. Thus, this review study aimed to classify the articles investigating the impact of interventional programs on marital intimacy after marriage.</p><p><strong>SEARCH METHODS:</strong> In April 2015, we performed a general search in Google Scholar search engines, and then we did an advanced search the databases of Science Direct, ProQuest, SID, Magiran, Irandoc, Pubmed, Scopus, <a href="http://www.cochranelibrary.com/">Cochrane Library</a>, and Psych info; Cumulative Index to Nursing and Allied Health Literature (CINAHL). Also, lists of the references of the relevant articles were reviewed for additional citations. Using Medical Subject Headings (MESH) keywords: Intervention (Clinical Trials, Non-Randomized Controlled Trials, Randomized Controlled Trials, Education), intimacy, marital (Marriage) and selected related articles to the study objective were from 1995 to April 2015. Clinical trials that evaluated one or more behavioral interventions to improve marital intimacy were reviewed in the study.</p><p><strong>MAIN RESULTS:</strong> 39 trials met the inclusion criteria. Eleven interventions had follow-up, and 28 interventions lacked follow-up. The quality evidence for 22 interventions was low, for 15 interventions moderate, and for one intervention was considered high. Findings from studies were categorized in 11 categories as the intimacy promoting interventions in dimensions of emotional, psychological, physical, sexual, temporal, communicational, social and recreational, aesthetic, spiritual, intellectual intimacy, and total intimacy.</p><p><strong>AUTHORS’ CONCLUSIONS:</strong> Improving and promoting communication, problem solving, self-disclosure and empathic response skills and sexual education and counseling in the form of cognitive-behavioral techniques and based on religious and cultural context of each society, an effective step can be taken to enhance marital intimacy and strengthen family bonds and stability. Health care providers should consider which interventions are appropriate to the couple characteristics and their relationships.</p>

scholarly journals High-cited favorable studies for COVID-19 treatments ineffective in large trials

2022 ◽  
Author(s):  
John P.A. Ioannidis
Keyword(s):  
Clinical Trials ◽  
Randomized Controlled Trials ◽  
Clinical Studies ◽  
Observational Studies ◽  
Randomized Trials ◽  
Controlled Trials ◽  
Randomized Controlled ◽  
Wide Dissemination ◽  
Highly Cited Articles ◽  
Highly Cited

Importance. COVID-19 has resulted in massive production, publication and wide dissemination of clinical studies trying to identify effective treatments. However, several widely touted treatments failed to show effectiveness in large well-done randomized controlled trials (RCTs). Objective. To evaluate for COVID-19 treatments that showed no benefits in subsequent large RCTs how many of their most-cited clinical studies had declared favorable results for these interventions. Methods. Scopus (last update December 23, 2021) identified articles on lopinavir-ritonavir, hydroxycholoroquine/azithromycin, remdesivir, convalescent plasma, colchicine or interferon (index interventions) that represented clinical trials and that had received >150 citations. Their conclusions were assessed and correlated with study design features. The ten most recent citations for the most-cited article on each index intervention were examined on whether they were critical to the highly-cited study. Altmetric scores were also obtained. Findings. 40 articles of clinical studies on these index interventions had received >150 citations (7 exceeded 1,000 citations). 20/40 (50%) had favorable conclusions and 4 were equivocal. Highly-cited articles with favorable conclusions were rarely RCTs while those without favorable conclusions were mostly RCTs (3/20 vs 15/20, p=0.0003). Only 1 RCT with favorable conclusions had sample size >160. Citation counts correlated strongly with Altmetric scores, in particular news items. Only 9 (15%) of 60 recent citations to the most highly-cited studies with favorable or equivocal conclusions were critical to the highly-cited study. Conclusion. Many clinical studies with favorable conclusions for largely ineffective COVID-19 treatments are uncritically heavily cited and disseminated. Early observational studies and small randomized trials may cause spurious claims of effectiveness that get perpetuated.

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