Statistical methods for unidirectional switch designs: Past, present, and future

2017 ◽  
Vol 27 (9) ◽  
pp. 2872-2882 ◽  
Author(s):  
Zhuozhao Zhan ◽  
Geertruida H de Bock ◽  
Edwin R van den Heuvel
Keyword(s):  
Statistical Methods ◽  
Large Scale ◽  
Sample Size Calculation ◽  
Complex Interventions ◽  
New Drugs ◽  
Control Treatment ◽  
Future Research ◽  
Control Group ◽  
Unified Framework ◽  
New Treatment

Clinical trials may apply or use a sequential introduction of a new treatment to determine its efficacy or effectiveness with respect to a control treatment. The reasons for choosing a particular switch design have different origins. For instance, they may be implemented for ethical or logistic reasons or for studying disease-modifying effects. Large-scale pragmatic trials with complex interventions often use stepped wedge designs (SWDs), where all participants start at the control group, and during the trial, the control treatment is switched to the new intervention at different moments. They typically use cross-sectional data and cluster randomization. On the other hand, new drugs for inhibition of cognitive decline in Alzheimer’s or Parkinson’s disease typically use delayed start designs (DSDs). Here, participants start in a parallel group design and at a certain moment in the trial, (part of) the control group switches to the new treatment. The studies are longitudinal in nature, and individuals are being randomized. Statistical methods for these unidirectional switch designs (USD) are quite complex and incomparable, and they have been developed by various authors under different terminologies, model specifications, and assumptions. This imposes unnecessary barriers for researchers to compare results or choose the most appropriate method for their own needs. This paper provides an overview of past and current statistical developments for the USDs (SWD and DSD). All designs are formulated in a unified framework of treatment patterns to make comparisons between switch designs easier. The focus is primarily on statistical models, methods of estimation, sample size calculation, and optimal designs for estimation of the treatment effect. Other relevant open issues are being discussed as well to provide suggestions for future research in USDs.

scholarly journals Long-Term Effect of Interactive Online Dietician Weight Loss Advice in General Practice (LIVA) Protocol for a Randomized Controlled Trial

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Carl J. Brandt ◽  
Vibeke Brandt ◽  
Mathilde Pedersen ◽  
Dorte Glintborg ◽  
Søren Toubro ◽  
...  
Keyword(s):  
Weight Loss ◽  
General Practice ◽  
Large Scale ◽  
Controlled Trial ◽  
Complex Interventions ◽  
Control Group ◽  
Average Weight ◽  
Practice Setting ◽  
Management Support ◽  
General Practice Setting

Background. Internet-based complex interventions aiming to promote weight loss and optimize healthy behaviors have attracted much attention. However, evidence for effect is lacking. Obesity is a growing problem, resulting in an increasing demand for cost efficient weight loss programs suitable for use on a large scale, for example, as part of standard primary care. In a previous pilot project by Brandt et al. (2011) without a control group, we examined the effects of online dietician counseling and found an average weight loss of 7.0 kg (95% CI: 4.6 to 9.3 kg) after 20 months. Aims and Methods. To analyze the effects of a complex intervention using trained dieticians in a general practice setting combined with internet-based interactive and personalized weight management support compared with conventional advice with a noninteractive internet support as placebo treatment in 340 overweight patients during a 2-year period. Primary endpoints are weight loss and lowering of cholesterol (LDL). We will also explore patients’ sociodemographics and use of the intervention as well as the health professionals’ views and perceptions of the intervention (their role and the advice and support that they provide). Perspective. The project will generate knowledge on the cost-effectiveness of a complex internet-based intervention in a general practice setting and on barriers and acceptability among professionals and patients.

scholarly journals TREATMENT SWITCHING: STATISTICAL AND DECISION-MAKING CHALLENGES AND APPROACHES

2016 ◽  
Vol 32 (3) ◽  
pp. 160-166 ◽  
Author(s):  
Nicholas R. Latimer ◽  
Chris Henshall ◽  
Uwe Siebert ◽  
Helen Bell
Keyword(s):  
Statistical Methods ◽  
Failure Time ◽  
Controlled Trial ◽  
International Workshop ◽  
Experimental Treatment ◽  
Decision Makers ◽  
Control Group ◽  
Intention To Treat ◽  
Treatment Switching ◽  
New Treatment

Objectives: Treatment switching refers to the situation in a randomized controlled trial where patients switch from their randomly assigned treatment onto an alternative. Often, switching is from the control group onto the experimental treatment. In this instance, a standard intention-to-treat analysis does not identify the true comparative effectiveness of the treatments under investigation. We aim to describe statistical methods for adjusting for treatment switching in a comprehensible way for nonstatisticians, and to summarize views on these methods expressed by stakeholders at the 2014 Adelaide International Workshop on Treatment Switching in Clinical Trials.Methods: We describe three statistical methods used to adjust for treatment switching: marginal structural models, two-stage adjustment, and rank preserving structural failure time models. We draw upon discussion heard at the Adelaide International Workshop to explore the views of stakeholders on the acceptability of these methods.Results: Stakeholders noted that adjustment methods are based on assumptions, the validity of which may often be questionable. There was disagreement on the acceptability of adjustment methods, but consensus that when these are used, they should be justified rigorously. The utility of adjustment methods depends upon the decision being made and the processes used by the decision-maker.Conclusions: Treatment switching makes estimating the true comparative effect of a new treatment challenging. However, many decision-makers have reservations with adjustment methods. These, and how they affect the utility of adjustment methods, require further exploration. Further technical work is required to develop adjustment methods to meet real world needs, to enhance their acceptability to decision-makers.

Death Anxiety Reduction as the Result of Exposure to a Death and Dying Symposium

1984 ◽  
Vol 14 (4) ◽  
pp. 323-328 ◽  
Author(s):  
David A. Waldman ◽  
Charles Davidshofer
Keyword(s):  
Undergraduate Students ◽  
Media Coverage ◽  
Death Anxiety ◽  
Large Scale ◽  
Death And Dying ◽  
Anxiety Reduction ◽  
Future Research ◽  
Control Group ◽  
Control Group Design ◽  
Colorado State University

The purpose of this study was to measure the effect of a three-week death and dying symposium at Colorado State University on attitudes and anxiety related to death, dying, and grief. A prepost control group design was employed using psychology undergraduate students as participants. Because of an overall finding of low participant attendance at the symposium events, participants who attended at least one event were assigned to the treatment group for data analyses. Results indicated lower death anxiety for students in both the treatment and control groups. The findings are discussed in terms of the widespread media coverage and informal discussions which accompany large-scale symposiums. Future research is suggested regarding the dynamic effects of such death and dying symposiums in relation to both attendants and nonattendants.

scholarly journals Assessing large-scale weekly cycles in meteorological variables: a review

2012 ◽  
Vol 12 (13) ◽  
pp. 5755-5771 ◽  
Author(s):  
A. Sanchez-Lorenzo ◽  
P. Laux ◽  
H.-J. Hendricks Franssen ◽  
J. Calbó ◽  
S. Vogl ◽  
...  
Keyword(s):  
Statistical Methods ◽  
Large Scale ◽  
Anthropogenic Activities ◽  
Statistical Significance ◽  
Meteorological Variables ◽  
Future Research ◽  
Scientific Debate ◽  
The Us ◽  
The World ◽  
Weekly Cycles

Abstract. Several studies have claimed to have found significant weekly cycles of meteorological variables appearing over large domains, which can hardly be related to urban effects exclusively. Nevertheless, there is still an ongoing scientific debate whether these large-scale weekly cycles exist or not, and some other studies fail to reproduce them with statistical significance. In addition to the lack of the positive proof for the existence of these cycles, their possible physical explanations have been controversially discussed during the last years. In this work we review the main results about this topic published during the recent two decades, including a summary of the existence or non-existence of significant weekly weather cycles across different regions of the world, mainly over the US, Europe and Asia. In addition, some shortcomings of common statistical methods for analyzing weekly cycles are listed. Finally, a brief summary of supposed causes of the weekly cycles, focusing on the aerosol-cloud-radiation interactions and their impact on meteorological variables as a result of the weekly cycles of anthropogenic activities, and possible directions for future research, is presented.

scholarly journals Chinese Herbal Medicine Banxiaxiexin Decoction Treating Diabetic Gastroparesis: A Systematic Review of Randomized Controlled Trials

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Jiaxing Tian ◽  
Min Li ◽  
Jiangquan Liao ◽  
Junling Li ◽  
Xiaolin Tong
Keyword(s):  
Methodological Quality ◽  
Large Scale ◽  
Data Extraction ◽  
Cochrane Review ◽  
Gastrointestinal Symptoms ◽  
Diabetic Gastroparesis ◽  
Future Research ◽  
Control Group ◽  
Gastric Emptying Rate ◽  
Randomized Controlled

Objective. To assess the current clinical evidence of Banxiaxiexin decoction for diabetic gastroparesis (DGP).Methods. Electronic databases were searched until December 2012. No language limitations were applied. We included RCTs using Banxiaxiexin decoction/modified Banxiaxiexin decoction for DGP. No restriction for the control group except acupuncture. Applying clinical effective rate as the main outcome index. Data extraction, analyses and quality assessment were conducted according to the Cochrane review standards.Results. 16 RCTs involving 1302 patients were finally identified, and the methodological quality was evaluated as generally low. The data showed that the effect of Banxiaxiexin decoction (BXXD) for DGP was superior to the control group (n=1302, RR 1.23, 95% CI 1.17 to 1.29,Z=8.04,P<0.00001). Only one trial recorded adverse events, no obvious adverse event occurred.Conclusions. Banxiaxiexin decoction could regain the gastric emptying rate and improve diabetic gastrointestinal symptoms. However, the methodological quality of included studies is low, and long term efficacy and safety are still uncertain, which indicates that the findings above should be read with caution. Thereby, well-designed, large-scale, and high-quality randomized controlled clinical trials with scientific rigor are warranted for stronger evidence in future research.

Personalized coupons for lower-calorie fast-food choices among young German adults and the influence of consumers' nutritional attitudes on promotion effectiveness

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Minh Thi Thuy Nguyen ◽  
Agnes Emberger-Klein ◽  
Klaus Menrad
Keyword(s):  
Fast Food ◽  
Food Choices ◽  
Economic Benefits ◽  
Control Treatment ◽  
Current Evidence ◽  
Future Research ◽  
Control Group ◽  
Grocery Stores ◽  
Post Intervention ◽  
Content Type

PurposePersonalized price promotion (PPP) is a marketing instrument that addresses the limitations of untargeted promotions by tailoring the offers to individual customers based on their purchase histories. Current evidence on PPP is limited to its immediate effects on buying behaviors at grocery stores and food companies' economic benefits. Moreover, little is known about the role of consumer characteristics in determining how effectively this promotional tool works. Hence, we aim to assess the effectiveness of PPP in promoting healthy fast food and which consumer-specific factors affect its performance.Design/methodology/approachThe authors conduct a laboratory experiment to examine the effects of personalized and non-personalized coupons for lower-calorie fast food menus on food and calorie selection. The coupon personalization is based on participants' menu choices, calorie needs and deal proneness. The authors additionally investigate how post-intervention changes are influenced by consumers' estimation of their selected calories, and their attitudes toward nutrition.FindingsRecipients of personalized incentives are more likely than participants in the control group to redeem the offered coupons, select more healthy items and reduce their selected calories. Such changes are less likely among participants underestimating the calorie content of their menu choices and perceiving higher barriers to healthy eating. Personalized coupons perform better even among subjects receiving lower discounting levels than the control treatment.Originality/valueAs the first to evaluate the effectiveness of PPP in encouraging healthy food choices, this study highlights the potential of this cutting-edge price intervention and provides valuable implications for future research.

Anger-Control Group Counseling for Women Recovering From Alcohol or Drug Addiction

2008 ◽  
Vol 18 (6) ◽  
pp. 616-625 ◽  
Author(s):  
A. Antonio González-Prendes
Keyword(s):  
Drug Addiction ◽  
Relapse Prevention ◽  
Work Practice ◽  
Social Work Practice ◽  
Control Treatment ◽  
Future Research ◽  
Control Group ◽  
Attributional Styles ◽  
Anger Control ◽  
Experimental Conditions

Two experimental conditions, a manualized cognitive-behavioral anger-control treatment incorporating empowerment strategies and a relapse-prevention treatment without the anger-control component, were compared to assess their impact on levels of trait anger and attributional styles of women recovering from alcohol and drug addiction. Participants were predominantly African American, low-socioeconomic-level women living in a residential facility in a major Midwestern city. Although significant changes were found for the anger-control group participants, sample size (anger control n = 8, relapse prevention n = 5) and participant characteristics call for caution when interpreting the results and limit the generalizability of the intervention. As a preliminary study, the findings are encouraging. Recommendations for future research and implications for social work practice are discussed.

scholarly journals Acupuncture Treatment of Lateral Elbow Pain: A Nonrandomized Pilot Study

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yan-Song Liu ◽  
Marcus Gadau ◽  
Guo-Xue Zhang ◽  
Hao Liu ◽  
Fu-Chun Wang ◽  
...  
Keyword(s):  
Pilot Study ◽  
Large Scale ◽  
Control Treatment ◽  
Laser Acupuncture ◽  
Control Group ◽  
Dash Score ◽  
Elbow Pain ◽  
Lateral Elbow Pain ◽  
Lateral Elbow ◽  
The Future

In planning for a large-scale multicenter trial to evaluate the effect of acupuncture for the treatment of lateral elbow pain, a pilot study was conducted. This was a prospective, investigator- and patient-blinded, nonrandomized, placebo controlled trial. Subjects were evaluated at baseline, before fourth, seventh, and ninth treatment, and at a two-week posttreatment follow-up. The treatment group received unilateral acupuncture at LI 10 and LI 11 at the affected side with manual needle manipulation; the control group received sham-laser acupuncture at the same acupoints. Measures included (i) disabilities of the arm, shoulder, and hand (DASH) questionnaire, (ii) pain-free grip strength (PFGS), and (iii) a visual analogue scale (VAS) for pain. Significant differences in DASH score, PFGS, and VAS between treatment and control group were found at the ninth treatment (n=20for each group,P<0.05). Only DASH showed significant differences compared to the control for all the measurement time points after treatment commenced and appears to be a sensitive and appropriate primary outcome measure for the future multisite trial. Results from this pilot study provided relevant information about treatment efficacy, credibility of control treatment, and sensitivity of different outcome measures for the planning of the future trial.

scholarly journals Assessing large-scale weekly cycles in meteorological variables: a review

2012 ◽  
Vol 12 (1) ◽  
pp. 1451-1491 ◽  
Author(s):  
A. Sanchez-Lorenzo ◽  
P. Laux ◽  
H.-J. Hendricks-Franssen ◽  
J. Calbó ◽  
S. Vogl ◽  
...  
Keyword(s):  
Statistical Methods ◽  
Large Scale ◽  
Anthropogenic Activities ◽  
Statistical Significance ◽  
Meteorological Variables ◽  
Future Research ◽  
Scientific Debate ◽  
The Us ◽  
The World ◽  
Weekly Cycles

Abstract. Several studies have claimed to have found significant weekly cycles of meteorological variables appearing over large domains, which can hardly be related to urban effects exclusively. Nevertheless, there is still an ongoing scientific debate whether these large-scale weekly cycles exist or not, and some other studies fail to reproduce them with statistical significance. In addition to the lack of the positive proof for the existence of these cycles, their possible physical explanations have been controversially discussed during the last years. In this work we review the main results about this topic published during the recent two decades, including a summary of the existence or non-existence of significant weekly weather cycles across different regions of the world, mainly over the US, Europe and Asia. In addition, some shortcomings of common statistical methods for analyzing weekly cycles are listed. Finally, a brief summary of supposed causes of the weekly cycles, focusing on the aerosol-cloud-radiation interactions and their impact on meteorological variables as a result of the weekly cycles of anthropogenic activities, and possible directions for future research, is presented.

Effects of Natural Products on Neuromuscular Junction

2021 ◽  
Vol 19 ◽  
Author(s):  
Esra Küpeli Akkol ◽  
Gökçe Şeker Karatoprak ◽  
Elif Carpar ◽  
Yaseen Hussain ◽  
Haroon Khan ◽  
...  
Keyword(s):  
Neuromuscular Junction ◽  
Antioxidant Activities ◽  
Immunosuppressive Drugs ◽  
New Drugs ◽  
Herbal Remedies ◽  
Future Research ◽  
Clinical Practices ◽  
Wide Range ◽  
New Treatment ◽  
Plant Sources

: Neuromuscular junction (NMJ) disorders result from damage, malfunction or absence of one or more key proteins involved in neuromuscular transmission, comprising a wide range of disorders. The most common pathology is antibody-mediated or downregulation of ion channels or receptors, resulting in Lambert-Eaton myasthenic syndrome, myasthenia gravis, and acquired neuromyotonia (Isaac’s syndrome), and rarely congenital myasthenic syndromes caused by mutations in NMJ proteins. A wide range of symptomatic treatments, immunomodulating therapies, or immunosuppressive drugs have been used to treat NMJ diseases. Future research must be directed at better understanding of the pathogenesis of these diseases, and developing novel disease-specific treatments. Numerous secondary metabolites, especially alkaloids isolated from plants have been used to treat NMJ diseases in traditional and clinical practices. An ethnopharmacological approach has provided leads for identifying new treatment for NMJ diseases. In this review, we performed a literature survey in Pubmed, Science Direct, and Google Scholar to gather information on drug discovery from plant sources for NMJ disease treatments. To date, most research has focused on the effect of herbal remedies on cholinesterase inhibitory and antioxidant activities. This review provides leads for identifying potential new drugs from plant sources for the treatment of NMJ diseases.

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