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Zhan Z, de Bock GH, van den Heuvel ER. Comparison of analysis methods and design choices for treatment-by-period interaction in unidirectional switch designs: a simulation study. BMC Med Res Methodol 2022; 22:294. [PMID: 36396984 PMCID: PMC9673415 DOI: 10.1186/s12874-022-01765-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 10/14/2022] [Indexed: 11/19/2022] Open
Abstract
Background Due to identifiability problems, statistical inference about treatment-by-period interactions has not been discussed for stepped wedge designs in the literature thus far. Unidirectional switch designs (USDs) generalize the stepped wedge designs and allow for estimation and testing of treatment-by-period interaction in its many flexible design forms. Methods Under different forms of the USDs, we simulated binary data at both aggregated and individual levels and studied the performances of the generalized linear mixed model (GLMM) and the marginal model with generalized estimation equations (GEE) for estimating and testing treatment-by-period interactions. Results The parallel group design had the highest power for detecting the treatment-by-period interactions. While there was no substantial difference between aggregated-level and individual-level analysis, the GLMM had better point estimates than the marginal model with GEE. Furthermore, the optimal USD for estimating the average treatment effect was not efficient for treatment-by-period interaction and the marginal model with GEE required a substantial number of clusters to yield unbiased estimates of the interaction parameters when the correlation structure is autoregressive of order 1 (AR1). On the other hand, marginal model with GEE had better coverages than GLMM under the AR1 correlation structure. Conclusion From the designs and methods evaluated, in general, parallel group design with a GLMM is, preferred for estimation and testing of treatment-by-period interaction in a clustered randomized controlled trial for a binary outcome. Supplementary Information The online version contains supplementary material available at 10.1186/s12874-022-01765-9.
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Thurm A, Kelleher B, Wheeler A. Outcome Measures for Core Symptoms of Intellectual Disability: State of the Field. AMERICAN JOURNAL ON INTELLECTUAL AND DEVELOPMENTAL DISABILITIES 2020; 125:418-433. [PMID: 33211819 DOI: 10.1352/1944-7558-125.6.418] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Accepted: 07/28/2020] [Indexed: 06/11/2023]
Abstract
Intellectual disability (ID) is defined by impairments in intellectual and adaptive functioning. As such, tools designed to assess these domains would theoretically be ideal outcome measures for treatment trials targeting core symptoms of ID. However, measures of intellectual and adaptive functioning have rarely been used as primary outcome measures to date and further study is needed regarding their usefulness to measure change. This area of inquiry is important because promising, mechanism-modifying treatments for conditions leading to ID are being initiated. To show efficacy, these treatments need to demonstrate an impact on core features of ID. After reviewing literature on this topic, we suggest solutions to several problems outlined, including use of out-of-age-range testing, alternative metrics, and development of new measures.
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Affiliation(s)
- Audrey Thurm
- Audrey Thurm, National Institute of Mental Health
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Zhan Z, de Bock GH, van den Heuvel ER. Statistical methods for unidirectional switch designs: Past, present, and future. Stat Methods Med Res 2017; 27:2872-2882. [PMID: 28125927 DOI: 10.1177/0962280216689280] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
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.
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Affiliation(s)
- Zhuozhao Zhan
- 1 Department of Epidemiology, University Medical Center Groningen, the Netherlands
| | - Geertruida H de Bock
- 1 Department of Epidemiology, University Medical Center Groningen, the Netherlands
| | - Edwin R van den Heuvel
- 2 Department of Mathematics and Computer Science, Technology University Eindhoven, the Netherlands
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Zwanenburg RJ, Bocca G, Ruiter SAJ, Dillingh JH, Flapper BCT, van den Heuvel ER, van Ravenswaaij-Arts CMA. Is there an effect of intranasal insulin on development and behaviour in Phelan-McDermid syndrome? A randomized, double-blind, placebo-controlled trial. Eur J Hum Genet 2016; 24:1696-1701. [PMID: 27577546 PMCID: PMC5117914 DOI: 10.1038/ejhg.2016.109] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 07/08/2016] [Accepted: 07/19/2016] [Indexed: 12/24/2022] Open
Abstract
Phelan-McDermid syndrome (PMS) or 22q13.3 deletion syndrome is a rare neurodevelopmental disorder with at least 60 children and 35 adults diagnosed in the Netherlands. Clinical features are moderate to severe intellectual disability and behavioural problems in the autism spectrum. Other researchers had observed a beneficial effect of intranasal insulin on development and behaviour in a pilot study in six children with PMS. To validate this effect, we conducted a randomized, double-blind, placebo-controlled clinical trial using a stepped-wedge design. From March 2013 to June 2015, 25 children aged 1-16 years with a molecularly confirmed 22q13.3 deletion including the SHANK3 gene participated in the clinical trial for a period of 18 months. Starting 6 months before the trial, children were systematically assessed for cognitive, language and motor development and for adaptive, social and emotional behaviour every 6 months. The second, third and fourth assessments were followed by daily nose sprays containing either intranasal insulin or intranasal placebo for a 6-month period. A fifth assessment was done directly after the end of the trial. Intranasal insulin did not cause serious adverse events. It increased the level of developmental functioning by 0.4-1.4 months per 6-month period, but the effect was not statistically significant in this small group. We found a stronger effect of intranasal insulin, being significant for cognition and social skills, for children older than 3 years, who usually show a decrease of developmental growth. However, clinical trials in larger study populations are required to prove the therapeutic effect of intranasal insulin in PMS.
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Affiliation(s)
- Renée J Zwanenburg
- University of Groningen, University Medical Centre Groningen, Department of Genetics, Groningen, The Netherlands
| | - Gianni Bocca
- University of Groningen, University Medical Centre Groningen, Beatrix Children's Hospital, Department of Paediatrics, Groningen, The Netherlands
| | - Selma A J Ruiter
- De Kinderacademie Groningen, Centre of Expertise for Child Development Care and Research, Groningen, The Netherlands
| | - Jan H Dillingh
- University of Groningen, University Medical Centre Groningen, Department of Clinical Pharmacy and Pharmacology, Groningen, The Netherlands
| | - Boudien C T Flapper
- University of Groningen, University Medical Centre Groningen, Beatrix Children's Hospital, Department of Paediatrics, Groningen, The Netherlands
| | - Edwin R van den Heuvel
- Department of Mathematics and Computer Science, Eindhoven University of Technology, Eindhoven, The Netherlands
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Zhan Z, de Bock GH, Wiggers T, van den Heuvel E. The analysis of terminal endpoint events in stepped wedge designs. Stat Med 2016; 35:4413-4426. [PMID: 27311403 DOI: 10.1002/sim.7004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 05/03/2016] [Accepted: 05/04/2016] [Indexed: 12/25/2022]
Abstract
The stepped wedge design is a unique clinical trial design that allows for a sequential introduction of an intervention. However, the statistical analysis is unclear when this design is applied in survival data. The time-dependent introduction of the intervention in combination with terminal endpoints and interval censoring makes the analysis more complicated. In this paper, a time-on-study scale discrete survival model was constructed. Simulations were conducted primarily to study the performance of our model for different settings of the stepped wedge design. Secondary, we compared our approach to continuous Cox proportional hazard model. The results show that the discrete survival model estimates the intervention effects unbiasedly. If the length of the censoring interval is increased, the precision of the estimates is decreased. Without left truncation and late entry, the number of steps improves the precision of the estimates, whereas in combination of left truncation and late entry, the number of steps decreases the precision. Given the same number of participants and clusters, a parallel group design has higher precision than a stepped wedge design. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Zhuozhao Zhan
- Department of Epidemiology, University Medical Center Groningen, Groningen, The Netherlands
| | - Geertruida H de Bock
- Department of Epidemiology, University Medical Center Groningen, Groningen, The Netherlands
| | - Theo Wiggers
- Department of Surgery, University Medical Center Groningen, Groningen, The Netherlands
| | - Edwin van den Heuvel
- Department of Epidemiology, University Medical Center Groningen, Groningen, The Netherlands. .,Department of Mathematics and Computer Science, Eindhoven University of Technology, Eindhoven, The Netherlands.
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Barker D, McElduff P, D'Este C, Campbell MJ. Stepped wedge cluster randomised trials: a review of the statistical methodology used and available. BMC Med Res Methodol 2016; 16:69. [PMID: 27267471 PMCID: PMC4895892 DOI: 10.1186/s12874-016-0176-5] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 05/28/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Previous reviews have focussed on the rationale for employing the stepped wedge design (SWD), the areas of research to which the design has been applied and the general characteristics of the design. However these did not focus on the statistical methods nor addressed the appropriateness of sample size methods used.This was a review of the literature of the statistical methodology used in stepped wedge cluster randomised trials. METHODS Literature Review. The Medline, Embase, PsycINFO, CINAHL and Cochrane databases were searched for methodological guides and RCTs which employed the stepped wedge design. RESULTS This review identified 102 trials which employed the stepped wedge design compared to 37 from the most recent review by Beard et al. 2015. Forty six trials were cohort designs and 45 % (n = 46) had fewer than 10 clusters. Of the 42 articles discussing the design methodology 10 covered analysis and seven covered sample size. For cohort stepped wedge designs there was only one paper considering analysis and one considering sample size methods. Most trials employed either a GEE or mixed model approach to analysis (n = 77) but only 22 trials (22 %) estimated sample size in a way which accounted for the stepped wedge design that was subsequently used. CONCLUSIONS Many studies which employ the stepped wedge design have few clusters but use methods of analysis which may require more clusters for unbiased and efficient intervention effect estimates. There is the need for research on the minimum number of clusters required for both types of stepped wedge design. Researchers should distinguish in the sample size calculation between cohort and cross sectional stepped wedge designs. Further research is needed on the effect of adjusting for the potential confounding of time on the study power.
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Affiliation(s)
- D Barker
- School of Medicine and Public Health, Faculty of Health, CCEB, HMRI Building, Level 4 West, University of Newcastle, University Drive, Callaghan, NSW, 2308, Australia.
| | - P McElduff
- School of Medicine and Public Health, Faculty of Health, CCEB, HMRI Building, Level 4 West, University of Newcastle, University Drive, Callaghan, NSW, 2308, Australia
| | - C D'Este
- School of Medicine and Public Health, Faculty of Health, CCEB, HMRI Building, Level 4 West, University of Newcastle, University Drive, Callaghan, NSW, 2308, Australia.,National Centre for Epidemiology and Population Health, Research School of Population Health, Australian National University, Canberra, ACT, 0200, Australia
| | - M J Campbell
- Medical Statistics Group, ScHARR, University of Sheffield, Sheffield, UK
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Zwanenburg RJ, Ruiter SA, van den Heuvel ER, Flapper BC, Van Ravenswaaij-Arts CM. Developmental phenotype in Phelan-McDermid (22q13.3 deletion) syndrome: a systematic and prospective study in 34 children. J Neurodev Disord 2016; 8:16. [PMID: 27118998 PMCID: PMC4845478 DOI: 10.1186/s11689-016-9150-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 04/08/2016] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Phelan-McDermid syndrome (PMS) or 22q13.3 deletion syndrome is characterized by global developmental delay, cognitive deficits, and behaviour in the autism spectrum. Knowledge about developmental and behavioural characteristics of this rare chromosomal disorder is still limited despite a rapid growing number of diagnoses. Our aim was to study a new and relatively large cohort to further characterize the developmental phenotype of children with PMS. METHODS We performed a descriptive study of children with a 22q13.3 deletion including SHANK3, aged 8 to 178 months, who were systematically (n = 34) and longitudinally (n = 29) assessed with standardized instruments: Bayley Scales of Infant and Toddler Development, third edition; Wechsler Preschool and Primary Scale of Intelligence, third edition; and Vineland Screener for Social and Adaptive Behavior. RESULTS Maximal developmental functioning ranged from 34 to 52 months depending on the developmental domain. In general, children performed poorest in the domain of language and best on the domain of motor (young children) or cognitive development (older children). At the individual level, 25 % scored better for receptive and 18 % for expressive language, whereas 22 % scored better for fine and 33 % for gross motor function. Developmental quotients were higher in younger children and decreased with age for all developmental domains, with 38 % of the children showing no improvement of cognitive developmental functioning. Almost all children (33/34) had significant deficits in adaptive behaviour. Children with very small deletions, covering only the SHANK3, ACR, and RABL2B genes, had a more favourable developmental phenotype. CONCLUSIONS Cognitive, motor, and especially language development were significantly impaired in all children with PMS but also highly variable and unpredictable. In addition, deficits in adaptive behaviour further hampered their cognitive development. Therefore, cognitive and behavioural characteristics should be evaluated and followed in each child with PMS to adapt supportive and therapeutic strategies to individual needs. Further research evaluating the relationship between deletion characteristics and the developmental phenotype is warranted to improve counselling of parents.
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Affiliation(s)
- Renée J. Zwanenburg
- />University of Groningen, University Medical Center Groningen, Department of Genetics, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
| | - Selma A.J. Ruiter
- />De Kinderacademie Groningen, Centre of Expertise for Child Development Care and Research, Herestraat 106, 9711 GH Groningen, The Netherlands
| | - Edwin R. van den Heuvel
- />Eindhoven University of Technology, Department of Mathematics and Computer Science, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - Boudien C.T. Flapper
- />University of Groningen, University Medical Center Groningen, Department of Pediatrics, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
| | - Conny M.A. Van Ravenswaaij-Arts
- />University of Groningen, University Medical Center Groningen, Department of Genetics, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
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Heo M, Kim N, Rinke ML, Wylie-Rosett J. Sample size determinations for stepped-wedge clinical trials from a three-level data hierarchy perspective. Stat Methods Med Res 2016; 27:480-489. [PMID: 26988927 DOI: 10.1177/0962280216632564] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Stepped-wedge (SW) designs have been steadily implemented in a variety of trials. A SW design typically assumes a three-level hierarchical data structure where participants are nested within times or periods which are in turn nested within clusters. Therefore, statistical models for analysis of SW trial data need to consider two correlations, the first and second level correlations. Existing power functions and sample size determination formulas had been derived based on statistical models for two-level data structures. Consequently, the second-level correlation has not been incorporated in conventional power analyses. In this paper, we derived a closed-form explicit power function based on a statistical model for three-level continuous outcome data. The power function is based on a pooled overall estimate of stratified cluster-specific estimates of an intervention effect. The sampling distribution of the pooled estimate is derived by applying a fixed-effect meta-analytic approach. Simulation studies verified that the derived power function is unbiased and can be applicable to varying number of participants per period per cluster. In addition, when data structures are assumed to have two levels, we compare three types of power functions by conducting additional simulation studies under a two-level statistical model. In this case, the power function based on a sampling distribution of a marginal, as opposed to pooled, estimate of the intervention effect performed the best. Extensions of power functions to binary outcomes are also suggested.
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Affiliation(s)
- Moonseong Heo
- 1 Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Namhee Kim
- 2 Department of Radiology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Michael L Rinke
- 3 Department of Pediatrics, Children's Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Judith Wylie-Rosett
- 1 Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY, USA.,4 Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
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Abstract
Phelan-McDermid syndrome (PMS), also called 22q13.3 deletion syndrome, is a neurodevelopmental disorder characterized by global developmental delay, intellectual disability, severe speech delays, poor motor tone and function, and autism spectrum disorder (ASD). Although the overall prevalence of PMS is unknown, there have been at least 1200 cases reported worldwide, according to the Phelan-McDermid Syndrome Foundation. PMS is now considered to be a relatively common cause of ASD and intellectual disability, accounting for between 0.5% and 2.0% of cases. The cause of PMS has been isolated to loss of function of one copy of SHANK3, which codes for a master scaffolding protein found in the postsynaptic density of excitatory synapses. Reduced expression of SH3 and multiple ankyrin repeat domains 3 (SHANK3) leads to reduced numbers of dendrites, and impaired synaptic transmission and plasticity. Recent mouse and human neuronal models of PMS have led to important opportunities to develop novel therapeutics, and at least 2 clinical trials are underway, one in the USA, and one in the Netherlands. The SHANK3 pathway may also be relevant to other forms of ASD, and many of the single-gene causes of ASD identified to date appear to converge on several common molecular pathways that underlie synaptic neurotransmission. As a result, treatments developed for PMS may also affect other forms of ASD.
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Affiliation(s)
- Jesse L. Costales
- />Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - Alexander Kolevzon
- />Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY USA
- />Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY USA
- />Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY USA
- />Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY USA
- />Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY USA
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