Strengths and weaknesses of a stepped wedge cluster randomized design: its application in a colorectal cancer follow-up study

Optimal designs using generalized estimating equations in cluster randomized crossover and stepped wedge trials

Cluster randomized crossover and stepped wedge cluster randomized trials are two types of longitudinal cluster randomized trials that leverage both the within- and between-cluster comparisons to estimate the treatment effect and are increasingly used in healthcare delivery and implementation science research. While the variance expressions of estimated treatment effect have been previously developed from the method of generalized estimating equations for analyzing cluster randomized crossover trials and stepped wedge cluster randomized trials, little guidance has been provided for optimal designs to ensure maximum efficiency. Here, an optimal design refers to the combination of optimal cluster-period size and optimal number of clusters that provide the smallest variance of the treatment effect estimator or maximum efficiency under a fixed total budget. In this work, we develop optimal designs for multiple-period cluster randomized crossover trials and stepped wedge cluster randomized trials with continuous outcomes, including both closed-cohort and repeated cross-sectional sampling schemes. Local optimal design algorithms are proposed when the correlation parameters in the working correlation structure are known. MaxiMin optimal design algorithms are proposed when the exact values are unavailable, but investigators may specify a range of correlation values. The closed-form formulae of local optimal design and MaxiMin optimal design are derived for multiple-period cluster randomized crossover trials, where the cluster-period size and number of clusters are decimal. The decimal estimates from closed-form formulae can then be used to investigate the performances of integer estimates from local optimal design and MaxiMin optimal design algorithms. One unique contribution from this work, compared to the previous optimal design research, is that we adopt constrained optimization techniques to obtain integer estimates under the MaxiMin optimal design. To assist practical implementation, we also develop four SAS macros to find local optimal designs and MaxiMin optimal designs.

Effect of a peer-led prevention program (P2P) on smoking in vocational high school students: Results from a two-school-year cluster-randomized trial

AIMS

The aim of this work was to measure the impact of P2P (i.e. peer-to-peer), a peer-led smoking prevention intervention, on daily smoking prevalence of adolescents over 2 school years.

DESIGN

A cluster-randomized controlled trial was performed over a 16-month follow-up (trial status: closed to follow-up). P2P was implemented 1-3 and 13-15 months after baseline. Assessments took place at baseline and 4, 10 and 16 months after baseline. The research team, assessors and adolescents were blinded to the study-arm assignment only at baseline.

SETTING

Fifteen vocational high schools in France were randomized into two clusters, using a 1:1 allocation ratio per French department (n intervention = 7, n control = 8).

PARTICIPANTS

Participants comprised a sample of 2010 students in year 11 (i.e. 15-16 years) in vocational high schools. A total of 437 students could not be assessed at baseline (absent or left school), yielding a total sample of 1573 students (n intervention = 749, n control = 824).

INTERVENTION AND COMPARATOR

The P2P programme trained voluntary students to become peer educators and design smoking prevention actions for their schoolmates in the intervention group (n = 945 students), compared with a passive control group (n = 1065 students).

MEASUREMENTS

The primary outcome was change from baseline in the prevalence of self-reported daily smoking (i.e. at least one cigarette per day) at 16 months.

FINDINGS

The 'time × group' interaction indicated that, compared with the control group, the intervention group had statistically significantly fewer daily smokers after 16 months [odds ratio (OR) = 0.33, 95% confidence interval (CI) = 0.20, 0.53]. Similarly, compared with the control group, the intervention group had statistically significantly fewer daily smokers after 4 months (OR = 0.50, 95% CI = 0.30, 0.82) and 10 months (OR = 0.60, 95% CI = 0.37, 0.98). No adverse events of P2P2 were reported.

CONCLUSIONS

A cluster-randomized trial found evidence that the peer-led P2P (peer-to-peer) smoking prevention intervention reduced the uptake of daily smoking among high school students in France over 16 months.

DANSPOT: A Multicenter Stepped-Wedge Cluster-Randomized Trial of the Reclassification of Acute Myocardial Infarction: Rationale and Study Design

BACKGROUND

Cardiac troponins are the preferred biomarkers for the diagnosis of acute myocardial infarction. Although sex-specific 99th percentile thresholds of troponins are recommended in international guidelines, the clinical effect of their use is poorly investigated. The DANSPOT Study (The Danish Study of Sex- and Population-Specific 99th percentile upper reference limits of Troponin) aims to evaluate the clinical effect of a prospective implementation of population- and sex-specific diagnostic thresholds of troponins into clinical practice.

METHODS

This study is a nationwide, multicenter, stepped-wedge cluster-randomized trial of the implementation of population- and sex-specific thresholds of troponins in 22 of 23 clinical centers in Denmark. We established sex-specific thresholds for 5 different troponin assays based on troponin levels in a healthy Danish reference population. Centers will sequentially cross over from current uniform manufacturer-derived thresholds to the new population- and sex-specific thresholds. The primary cohort is defined as patients with symptoms suggestive of acute coronary syndrome having at least 1 troponin measurement performed within 24 hours of arrival with a peak troponin value between the current uniform threshold and the new sex-specific female and male thresholds. The study will compare the occurrence of the primary outcome, defined as a composite of nonfatal myocardial infarction, unplanned revascularization, and all-cause mortality within 1 year, separately for men and women before and after the implementation of the new sex-specific thresholds.

CONCLUSIONS

The DANSPOT Study is expected to show the clinical effects on diagnostics, treatment, and clinical outcomes in patients with myocardial infarction of implementing sex-specific diagnostic thresholds for troponin based on a national Danish reference population.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT05336435.

An overview of optimal designs under a given budget in cluster randomized trials with a binary outcome

Cluster randomized trial design may raise financial concerns because the cost to recruit an additional cluster is much higher than to enroll an additional subject in subject-level randomized trials. Therefore, it is desirable to develop an optimal design. For local optimal designs, optimization means the minimum variance of the estimated treatment effect under the total budget. The local optimal design derived from the variance needs the input of an association parameter ρ in terms of a "working" correlation structure R ( ρ ) in the generalized estimating equation models. When the range of ρ instead of an exact value is available, the parameter space is defined as the range of ρ and the design space is defined as enrollment feasibility, for example, the number of clusters or cluster size. For any value ρ within the range, the optimal design and relative efficiency for each design in the design space is obtained. Then, for each design in the design space, the minimum relative efficiency within the parameter space is calculated. MaxiMin design is the optimal design that maximizes the minimum relative efficiency among all designs in the design space. Our contributions are threefold. First, for three common measures (risk difference, risk ratio, and odds ratio), we summarize all available local optimal designs and MaxiMin designs utilizing generalized estimating equation models when the group allocation proportion is predetermined for two-level and three-level parallel cluster randomized trials. We then propose the local optimal designs and MaxiMin designs using the same models when the group allocation proportion is undecided. Second, for partially nested designs, we develop the optimal designs for three common measures under the setting of equal number of subjects per cluster and exchangeable working correlation structure in the intervention group. Third, we create three new Statistical Analysis System (SAS) macros and update two existing SAS macros for all the optimal designs. We provide two examples to illustrate our methods.

Advanced practice physiotherapy care in emergency departments for patients with musculoskeletal disorders: a pragmatic cluster randomized controlled trial and cost analysis

BACKGROUND

Advanced practice physiotherapy (APP) models of care where physiotherapists are primary contact emergency department (ED) providers are promising models of care to improve access, alleviate physicians' burden, and offer efficient centered patient care for patients with minor musculoskeletal disorders (MSKD).

OBJECTIVES

To compare the effectiveness of an advanced practice physiotherapist (APPT)-led model of care with usual ED physician care for persons presenting with a minor MSKD, in terms of patient-related outcomes, health care resources utilization, and health care costs.

METHODS

This trial is a multicenter stepped-wedge cluster randomized controlled trial (RCT) with a cost analysis. Six Canadian EDs (clusters) will be randomized to a treatment sequence where patients will either be managed by an ED APPT or receive usual ED physician care. Seven hundred forty-four adults with a minor MSKD will be recruited. The main outcome measure will be the Brief Pain Inventory Questionnaire. Secondary measures will include validated self-reported disability questionnaires, the EQ-5D-5L, and other health care utilization outcomes such as prescription of imaging tests and medication. Adverse events and re-visits to the ED for the same complaint will also be monitored. Health care costs will be measured from the perspective of the public health care system using time-driven activity-based costing. Outcomes will be collected at inclusion, at ED discharge, and at 4, 12, and 26 weeks following the initial ED visit. Per-protocol and intention-to-treat analyses will be performed using linear mixed models with a random effect for cluster and fixed effect for time.

DISCUSSION

MSKD have a significant impact on health care systems. By providing innovative efficient pathways to access care, APP models of care could help relieve pressure in EDs while providing efficient care for adults with MSKD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05545917 . Registered on September 19, 2022.

Enhancing the quality of cognitive behavioral therapy in community mental health through artificial intelligence generated fidelity feedback (Project AFFECT): a study protocol

Background

Each year, millions of Americans receive evidence-based psychotherapies (EBPs) like cognitive behavioral therapy (CBT) for the treatment of mental and behavioral health problems. Yet, at present, there is no scalable method for evaluating the quality of psychotherapy services, leaving EBP quality and effectiveness largely unmeasured and unknown. Project AFFECT will develop and evaluate an AI-based software system to automatically estimate CBT fidelity from a recording of a CBT session. Project AFFECT is an NIMH-funded research partnership between the Penn Collaborative for CBT and Implementation Science and Lyssn.io, Inc. (“Lyssn”) a start-up developing AI-based technologies that are objective, scalable, and cost efficient, to support training, supervision, and quality assurance of EBPs. Lyssn provides HIPAA-compliant, cloud-based software for secure recording, sharing, and reviewing of therapy sessions, which includes AI-generated metrics for CBT. The proposed tool will build from and be integrated into this core platform.

Methods

Phase I will work from an existing software prototype to develop a LyssnCBT user interface geared to the needs of community mental health (CMH) agencies. Core activities include a user-centered design focus group and interviews with community mental health therapists, supervisors, and administrators to inform the design and development of LyssnCBT. LyssnCBT will be evaluated for usability and implementation readiness in a final stage of Phase I. Phase II will conduct a stepped-wedge, hybrid implementation-effectiveness randomized trial (N = 1,875 clients) to evaluate the effectiveness of LyssnCBT to improve therapist CBT skills and client outcomes and reduce client drop-out. Analyses will also examine the hypothesized mechanism of action underlying LyssnCBT.

Discussion

Successful execution will provide automated, scalable CBT fidelity feedback for the first time ever, supporting high-quality training, supervision, and quality assurance, and providing a core technology foundation that could support the quality delivery of a range of EBPs in the future.

Trial registration

ClinicalTrials.gov; NCT05340738; approved 4/21/2022.

Effects of Implementing the Short-Term Assessment of Risk and Treatability for Mechanical Restraint in a Forensic Male Population: A Stepped-Wedge, Cluster-Randomized Design

The assessment and formulation of the risk of violence and other unwanted behaviors at forensic psychiatric facilities have been attempted for decades. Structured professional judgment tools, such as the Short-Term Assessment of Risk and Treatability (START), are among the recent attempts to overcome the challenge of accomplishing these goals. This study examined the effect of implementing START in clinical practice for the most serious adverse events among the target group of severely mentally ill forensic psychiatric inpatients. Results were based on the use of mechanical restraints as an outcome. This study is a pragmatic, stepped-wedge, cluster-randomized controlled trial and was conducted over 5 years. It included eight forensic psychiatric units. Fifty out of 156 patients who had a basic aggression score of more than 0 were included in the study. We found that the rate of mechanical restraint use within the START period were 82% [relative risk (RR) = 0.18], lower than those outside of the START period. Patients evaluated within the START period were also found to have a 36% (RR = 0.64) lower risk of having higher Brøset Violence Checklist scores than patients evaluated outside the START period. Previous studies on START have primarily focused on validation, the predictive capability of the assessment, and implementation. We were only able to identify one study that aimed to identify the benefits and outcomes of START in a forensic setting. This study showed a significant reduction in the chance for inpatients in a forensic psychiatric facility to become mechanically restrained during periods where the START was used as risk assessment.

A stepped-wedge randomised controlled trial assessing the implementation, effectiveness and cost-consequences of the EDDIE+ hospital avoidance program in 12 residential aged care homes: study protocol

Background

Older people living in residential aged care homes experience frequent emergency transfers to hospital. These events are associated with risks of hospital acquired complications and invasive treatments or interventions. Evidence suggests that some hospital transfers may be unnecessary or avoidable. The Early Detection of Deterioration in Elderly residents (EDDIE) program is a multi-component intervention aimed at reducing unnecessary hospital admissions from residential aged care homes by empowering nursing and care staff to detect and manage early signs of resident deterioration. This study aims to implement and evaluate the program in a multi-site randomised study in Queensland, Australia.

Methods

A stepped-wedge randomised controlled trial will be conducted at 12 residential aged care homes over 58 weeks. The program has four components: education and training, decision support tools, diagnostic equipment, and implementation facilitation with clinical systems support. The integrated Promoting Action on Research Implementation in Health Services (i-PARIHS) framework will be used to guide the program implementation and process evaluation. The primary outcome measure will be the number of hospital bed days used by residents, with secondary outcomes assessing emergency department transfer rates, admission rates, length of stay, family awareness and experience, staff self-efficacy and costs of both implementation and health service use. A process evaluation will assess the extent and fidelity of program implementation, mechanisms of impact and the contextual barriers and enablers.

Discussion

The intervention is expected to improve outcomes by reducing unnecessary hospital transfers. Fewer hospital transfers and admissions will release resources for other patients with potentially greater needs. Residential aged care home staff might benefit from feelings of empowerment in their ability to proactively manage early signs of resident deterioration. The process evaluation will be useful for supporting wider implementation of this intervention and other similar initiatives.

Trial registration

The trial is prospectively registered with the Australia New Zealand Clinical Trial Registry (ACTRN12620000507987, registered 23/04/2020).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02294-8.

Health Economic Evaluation Alongside Stepped Wedge Trials: A Methodological Systematic Review

BACKGROUND

Recently, there has been an increase in use of the stepped wedge trial (SWT) design in the context of health services research, due to its pragmatic and methodological advantages over the parallel group design.

OBJECTIVE

Our objective was to summarise the statistical methods used when conducting economic evaluations alongside SWTs.

METHODS

A systematic literature search extending to February 2020 was conducted in the PubMed, Scopus, Cochrane and National Health Service Economic Evaluation Database (NHS-EED) databases to find and evaluate studies where there was an intention to conduct an economic evaluation alongside an SWT. Studies were assessed for their eligibility, findings, reporting of statistical methods and quality of reporting.

RESULTS

Of the 586 studies retrieved from the literature search, 69 studies were identified and included in this systematic review. A total of 54 studies were published protocols, with eight economic evaluations and seven studies reporting full trial results. Included studies varied in terms of their reporting of statistical methods, in both detail and methodology. There were 34 studies that did not report any statistical methods for the economic evaluation, and only 16 studies reported appropriate methods, mainly using some form of mixed/multilevel model, and two used seemingly unrelated regression. Twelve studies reported the use of generic bootstrap methods and other modelling techniques, whilst the remaining studies failed to appropriately account for clustering, correlation or adjustment for time.

CONCLUSIONS

The use of appropriate statistical methods that account for time, clustering and correlation between costs and outcomes is an important part of SWT health economics analysis, one that will benefit from an effort to communicate the methods available and their performance.

A stepped-wedge randomised-controlled trial assessing the implementation, impact and costs of a prospective feedback loop to promote appropriate care and treatment for older patients in acute hospitals at the end of life: study protocol

BACKGROUND

Hospitalisation rates for the older population have been increasing with end-of-life care becoming a more medicalised and costly experience. There is evidence that some of these patients received non-beneficial treatment during their final hospitalisation with a third of the non-beneficial treatment duration spent in intensive care units. This study aims to increase appropriate care and treatment decisions and pathways for older patients at the end of life in Australia. This study will implement and evaluate a prospective feedback loop and tailored clinical response intervention at three hospitals in Queensland, Australia.

METHODS

A stepped-wedge cluster randomised trial will be conducted with up to 21 clinical teams in three acute hospitals over 70 weeks. The study involves clinical teams providing care to patients aged 75 years or older, who are prospectively identified to be at risk of non-beneficial treatment using two validated tools for detecting death and deterioration risks. The intervention's feedback loop will provide the teams with a summary of these patients' risk profiles as a stimulus for a tailored clinical response in the intervention phase. The Consolidated Framework for Implementation Research will be used to inform the intervention's implementation and process evaluation. The study will determine the impact of the intervention on patient outcomes related to appropriate care and treatment at the end of life in hospitals, as well as the associated healthcare resource use and costs. The primary outcome is the proportion of patients who are admitted to intensive care units. A process evaluation will be carried out to assess the implementation, mechanisms of impact, and contextual barriers and enablers of the intervention.

DISCUSSION

This intervention is expected to have a positive impact on the care of older patients near the end of life, specifically to improve clinical decision-making about treatment pathways and what constitutes appropriate care for these patients. These will reduce the incidence of non-beneficial treatment, and improve the efficiency of hospital resources and quality of care. The process evaluation results will be useful to inform subsequent intervention implementation at other hospitals.

TRIAL REGISTRATION

Australia New Zealand Clinical Trial Registry (ANZCTR), ACTRN12619000675123p (approved 6 May 2019).

Implementation of a nurse-led self-management support intervention for patients with cancer-related pain: a cluster randomized phase-IV study with a stepped wedge design (EvANtiPain)

Background

Pain self-management support interventions were effective in controlled clinical trials and meta analyses. However, implementation of these complex interventions may not translate into identical effects. This paper evaluates the implementation of ANtiPain, a cancer pain self-management support intervention in routine clinical practice according to the Reach Efficacy-Adoption Implementation Maintenance framework.

Methods

In this cluster randomized study with a stepped wedge design, N = 153 adult patients with cancer-related pain were recruited from 01/17 to 05/18 on 17 wards of 3 hospitals in Vienna, Austria. ANtiPain entailed a face-to-face in-hospital session by a trained nurse to prepare discharge according to key strategies, information on pain self-management, and skills building. After discharge, cancer-pain self-management was coached via phone calls. Patient-level data were collected at recruitment, and 2, 4 and 8 weeks after discharge via postal or online questionnaire. Primary outcome was pain interference with daily activities. Secondary outcomes included pain intensity, self-efficacy, and patient satisfaction. Organizational-level data (e.g., on implementation procedures) were collected by study or intervention nurses. The mixed model to analyze patient-level data included a random intercept and a random slope for individual and a random intercept for ward.

Results

Recruitment was slower than expected and unevenly distributed over wards and hospitals. The face-to-face session was clinically feasible (mean duration = 33 min) as well as the mean amount (n = 2) and duration of phone calls (mean = 17 min). Only 16 (46%) of 35 trained nurses performed the intervention on nine wards. To deal with the loss of power, analyses were adapted. Overall effects on pain interference were not significant. However, effects were significant in sub analyses of the nine wards that recruited patients in the intervention period (p = .009). Regarding secondary outcomes, the group-by-time effect was significant for self-efficacy (p = .033), and patient satisfaction with information on pain-self-management (p = .002) and in-hospital pain management (p = .018).

Conclusions

The implementation of ANtiPain improved meaningful patient outcomes on wards that applied the intervention routinely. Our analyses showed that the implementation benefited from being embedded in larger scale projects to improve cancer pain management and that the selection of wards with a high percentage of oncology patients may be crucial.

Trial registration

ClinicalTrials.gov Identifier: NCT02891785 Date of registration: September 8, 2016.

Information growth for sequential monitoring of clinical trials with a stepped wedge cluster randomized design and unknown intracluster correlation

Background/aims

In a stepped wedge study design, study clusters usually start with the baseline treatment and then cross over to the intervention at randomly determined times. Such designs are useful when the intervention must be delivered at the cluster level and are becoming increasingly common in practice. In these trials, if the outcome is death or serious morbidity, one may have an ethical imperative to monitor the trial and stop before maximum enrollment if the new therapy is proven to be beneficial. In addition, because formal monitoring allows for the stoppage of trials when a significant benefit for new therapy has been ruled out, their use can make a research program more efficient. However, use of the stepped wedge cluster randomized study design complicates the implementation of standard group sequential monitoring methods. Both the correlation of observations introduced by the clustered randomization and the timing of crossover from one treatment to the other impact the rate of information growth, an important component of an interim analysis.

Methods

We simulated cross-sectional stepped wedge study data in order to evaluate the impact of sequential monitoring on the Type I error and power when the true intracluster correlation is unknown. We studied the impact of varying intracluster correlations, treatment effects, methods of estimating the information growth, and boundary shapes.

Results

While misspecified information growth can impact both the Type I error and power of a study in some settings, we observed little inflation of the Type I error and only moderate reductions in power across a range of misspecified information growth patterns in our simulations.

Conclusion

Taking the study design into account and using either an estimate of the intracluster correlation from the ongoing study or other data in the same clusters should allow for easy implementation of group sequential methods in future stepped wedge designs.

Implementation of a Cost-Effective Physical Therapy Approach (Coach2Move) to Improve Physical Activity in Community-Dwelling Older Adults With Mobility Problems: Protocol for a Cluster-Randomized, Stepped Wedge Trial

BACKGROUND

Coach2Move is a personalized treatment strategy by physical therapists to elicit physical activity in community-dwelling older adults with mobility problems.

OBJECTIVE

The primary objective of this study is to assess the effectiveness and cost-effectiveness of the implementation of Coach2Move compared with regular care physical therapy in daily clinical practice.

DESIGN, SETTING, PARTICIPANTS, AND INTERVENTION

A multicenter cluster-randomized stepped wedge trial is being implemented in 16 physical therapist practices (4 clusters of 4 practices in 4 steps) in the Netherlands. The study aims to include 400 older adults (≥70 years) living independently with mobility problems and/or physically inactive lifestyles. The intervention group receives physical therapy conforming to the Coach2Move strategy; the usual care group receives typical physical therapist care.

MEASUREMENTS

Measurements are taken at baseline and 3, 6, and 12 months after the start of treatment. The primary outcomes for effectiveness are the amount of physical activity (LASA Physical Activity Questionnaire) and functional mobility (Timed Up and Go test). Trial success can be declared if at least 1 parameter improves while another does not deteriorate. Secondary outcomes are level of frailty (Evaluative Frailty Index for Physical Activity), perceived effect (Global Perceived Effect and Patient Specific Complaints questionnaire), quality of life (EQ-5D-5 L), and health care expenditures. Multilevel linear regression analyses are used to compare the outcomes between treatment groups according to an intention-to-treat approach. Alongside the trial, a mixed-methods process evaluation is performed to understand the outcomes, evaluate therapist fidelity to the strategy, and detect barriers and facilitators in implementation.

LIMITATIONS

An important limitation of the study design is the inability to blind treating therapists to study allocation.

DISCUSSION

The trial provides insight into the effectiveness and cost-effectiveness of the Coach2Move strategy compared with usual care. The process evaluation provides insight into influencing factors related to outcomes and implementation.

A systematic review of multidisciplinary teams to reduce major amputations for patients with diabetic foot ulcers

OBJECTIVE

Multiple single-center studies have reported significant reductions in major amputations among patients with diabetic foot ulcers after initiation of multidisciplinary teams. The purpose of this study was to assess the association between multidisciplinary teams (ie, two or more types of clinicians working together) and the risk of major amputation and to compile descriptions of these diverse teams.

METHODS

We searched PubMed, Scopus, Cumulative Index to Nursing and Allied Health, and Cochrane Central Register of Controlled Trials from inception through May 24, 2019 for studies reporting the association between multidisciplinary teams and major amputation rates for patients with diabetic foot ulcers. We included original studies if ≥50% of the patients seen by the multidisciplinary team had diabetes, they included a control group, and they reported the effect of a multidisciplinary team on major amputation rates. Studies were excluded if they were non-English language, abstracts only, or unpublished. We used the five-domain Systems Engineering Initiative for Patient Safety Model to describe team composition and function and summarized changes in major amputation rates associated with multidisciplinary team care. A meta-analysis was not performed because of heterogeneity across studies, their observational designs, and the potential for uncontrolled confounding (PROSPERO No. 2017: CRD42017067915).

RESULTS

We included 33 studies, none of which were randomized trials. Multidisciplinary team composition and functions were highly diverse. However, four elements were common across teams: teams were composed of medical and surgical disciplines; larger teams benefitted from having a "captain" and a nuclear and ancillary team member structure; clear referral pathways and care algorithms supported timely, comprehensive care; and multidisciplinary teams addressed four key tasks: glycemic control, local wound management, vascular disease, and infection. Ninety-four percent (31/33) of studies reported a reduction in major amputations after institution of a multidisciplinary team.

CONCLUSIONS

Multidisciplinary team composition was variable but reduced major amputations in 94% of studies. Teams consistently addressed glycemic control, local wound management, vascular disease, and infection in a timely and coordinated manner to reduce major amputation for patients with diabetic foot ulcerations. Care algorithms and referral pathways were key tools to their success.

Follow-up strategies for patients treated for non-metastatic colorectal cancer

BACKGROUND

This is the fourth update of a Cochrane Review first published in 2002 and last updated in 2016.It is common clinical practice to follow patients with colorectal cancer for several years following their curative surgery or adjuvant therapy, or both. Despite this widespread practice, there is considerable controversy about how often patients should be seen, what tests should be performed, and whether these varying strategies have any significant impact on patient outcomes.

OBJECTIVES

To assess the effect of follow-up programmes (follow-up versus no follow-up, follow-up strategies of varying intensity, and follow-up in different healthcare settings) on overall survival for patients with colorectal cancer treated with curative intent. Secondary objectives are to assess relapse-free survival, salvage surgery, interval recurrences, quality of life, and the harms and costs of surveillance and investigations.

SEARCH METHODS

For this update, on 5 April 2109 we searched CENTRAL, MEDLINE, Embase, CINAHL, and Science Citation Index. We also searched reference lists of articles, and handsearched the Proceedings of the American Society for Radiation Oncology. In addition, we searched the following trials registries: ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform. We contacted study authors. We applied no language or publication restrictions to the search strategies.

SELECTION CRITERIA

We included only randomised controlled trials comparing different follow-up strategies for participants with non-metastatic colorectal cancer treated with curative intent.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Two review authors independently determined study eligibility, performed data extraction, and assessed risk of bias and methodological quality. We used GRADE to assess evidence quality.

MAIN RESULTS

We identified 19 studies, which enrolled 13,216 participants (we included four new studies in this second update). Sixteen out of the 19 studies were eligible for quantitative synthesis. Although the studies varied in setting (general practitioner (GP)-led, nurse-led, or surgeon-led) and 'intensity' of follow-up, there was very little inconsistency in the results.Overall survival: we found intensive follow-up made little or no difference (hazard ratio (HR) 0.91, 95% confidence interval (CI) 0.80 to 1.04: I² = 18%; high-quality evidence). There were 1453 deaths among 12,528 participants in 15 studies. In absolute terms, the average effect of intensive follow-up on overall survival was 24 fewer deaths per 1000 patients, but the true effect could lie between 60 fewer to 9 more per 1000 patients.Colorectal cancer-specific survival: we found intensive follow-up probably made little or no difference (HR 0.93, 95% CI 0.81 to 1.07: I² = 0%; moderate-quality evidence). There were 925 colorectal cancer deaths among 11,771 participants enrolled in 11 studies. In absolute terms, the average effect of intensive follow-up on colorectal cancer-specific survival was 15 fewer colorectal cancer-specific survival deaths per 1000 patients, but the true effect could lie between 47 fewer to 12 more per 1000 patients.Relapse-free survival: we found intensive follow-up made little or no difference (HR 1.05, 95% CI 0.92 to 1.21; I² = 41%; high-quality evidence). There were 2254 relapses among 8047 participants enrolled in 16 studies. The average effect of intensive follow-up on relapse-free survival was 17 more relapses per 1000 patients, but the true effect could lie between 30 fewer and 66 more per 1000 patients.Salvage surgery with curative intent: this was more frequent with intensive follow-up (risk ratio (RR) 1.98, 95% CI 1.53 to 2.56; I² = 31%; high-quality evidence). There were 457 episodes of salvage surgery in 5157 participants enrolled in 13 studies. In absolute terms, the effect of intensive follow-up on salvage surgery was 60 more episodes of salvage surgery per 1000 patients, but the true effect could lie between 33 to 96 more episodes per 1000 patients.Interval (symptomatic) recurrences: these were less frequent with intensive follow-up (RR 0.59, 95% CI 0.41 to 0.86; I² = 66%; moderate-quality evidence). There were 376 interval recurrences reported in 3933 participants enrolled in seven studies. Intensive follow-up was associated with fewer interval recurrences (52 fewer per 1000 patients); the true effect is between 18 and 75 fewer per 1000 patients.Intensive follow-up probably makes little or no difference to quality of life, anxiety, or depression (reported in 7 studies; moderate-quality evidence). The data were not available in a form that allowed analysis.Intensive follow-up may increase the complications (perforation or haemorrhage) from colonoscopies (OR 7.30, 95% CI 0.75 to 70.69; 1 study, 326 participants; very low-quality evidence). Two studies reported seven colonoscopic complications in 2292 colonoscopies, three perforations and four gastrointestinal haemorrhages requiring transfusion. We could not combine the data, as they were not reported by study arm in one study.The limited data on costs suggests that the cost of more intensive follow-up may be increased in comparison with less intense follow-up (low-quality evidence). The data were not available in a form that allowed analysis.

AUTHORS' CONCLUSIONS

The results of our review suggest that there is no overall survival benefit for intensifying the follow-up of patients after curative surgery for colorectal cancer. Although more participants were treated with salvage surgery with curative intent in the intensive follow-up groups, this was not associated with improved survival. Harms related to intensive follow-up and salvage therapy were not well reported.

The current use of feasibility studies in the assessment of feasibility for stepped-wedge cluster randomised trials: a systematic review

Background

Stepped-wedge cluster randomised trials (SW-CRTs) are a pragmatic trial design, providing an unprecedented opportunity to increase the robustness of evidence underpinning implementation and quality improvement interventions. Given the complexity of the SW-CRT, the likelihood of trials not delivering on their objectives will be mitigated if a feasibility study precedes the definitive trial. It is not currently known if feasibility studies are being conducted for SW-CRTs nor what the objectives of these studies are.

Methods

Searches were conducted of several databases to identify published feasibility studies which were designed to inform a future SW-CRT. For each eligible study, data were extracted on the characteristics of and rationale for the feasibility study; the process for determining progression to the main trial; how the feasibility study informed the main trial; and whether the main trial went ahead. A narrative synthesis and descriptive analysis are presented.

Results

Eleven feasibility studies were identified, which included eight completed study reports and three protocols. Three studies used a stepped-wedge design and these were the only studies to be randomised. Studies were predominantly of a mixed-methods design. Only one study assessed specific features related to the feasibility of using a SW-CRT and one investigated the time taken to complete the study procedures. The other studies were mostly assessing the feasibility and acceptability of the intervention.

Conclusion

Published feasibility studies for SW-CRTs are scarce and those that are being reported do not investigate issues specific to the complexities of the trial design. When conducting feasibility studies in advance of a definitive SW-CRT, researchers should consider assessing the feasibility of study procedures, particularly those specific to the SW-CRT design, and ensure that the findings are published for the benefit of other researchers.

Electronic supplementary material

The online version of this article (10.1186/s12874-019-0658-3) contains supplementary material, which is available to authorized users.

Systematic review showed that stepped-wedge cluster randomized trials often did not reach their planned sample size

OBJECTIVE

To determine how often stepped-wedge cluster randomized controlled trials reach their planned sample size, and what reasons are reported for choosing a stepped-wedge trial design.

STUDY DESIGN AND SETTING

We conducted a PubMed literature search (period 2012 to 2017) and included articles describing the results of a stepped-wedge cluster randomized trial. We calculated the percentage of studies reaching their prespecified number of participants and clusters, and we summarized the reasons for choosing the stepped-wedge trial design as well as difficulties during enrollment.

RESULTS

Forty-six individual stepped-wedge studies from a total of 53 articles were included in our review. Of the 35 studies, for which recruitment rate could be calculated, 69% recruited their planned number of participants, with 80% having recruited the planned number of clusters. Ethical reasons were the most common motivation for choosing the stepped-wedge trial design. Most important difficulties during study conduct were dropout of clusters and delayed implementation of the intervention.

CONCLUSION

About half of recently published stepped-wedge trials reached their planned sample size indicating that recruitment is also a major problem in these trials. Still, the stepped-wedge trial design can yield practical, ethical, and methodological advantages.

Effectiveness and Cost-benefit Evaluation of a Comprehensive Workers' Health Surveillance Program for Sustainable Employability of Meat Processing Workers

Objective To evaluate the effectiveness of a comprehensive workers' health surveillance (WHS) program on aspects of sustainable employability and cost-benefit. Methods A cluster randomized stepped wedge trial was performed in a Dutch meat processing company from february 2012 until march 2015. In total 305 workers participated in the trial. Outcomes were retrieved during a WHS program, by multiple questionnaires, and from company registries. Primary outcomes were sickness absence, work ability, and productivity. Secondary outcomes were health, vitality, and psychosocial workload. Data were analyzed with linear and logistic multilevel models. Cost-benefit analyses from the employer's perspective were performed as well. Results Primary outcomes sickness absence (OR = 1.40), work ability (B = -0.63) and productivity (OR = 0.71) were better in the control condition. Secondary outcomes did not or minimally differ between conditions. Of the 12 secondary outcomes, the only outcome that scored better in the experimental condition was meaning of work (B = 0.18). Controlling for confounders did not or minimally change the results. However, our stepped wedge design did not enable adjustment for confounding in the last two periods of the trial. The WHS program resulted in higher costs for the employer on the short and middle term. Conclusions Primary outcomes did not improve after program implementation and secondary outcomes remained equal after implementation. The program was not cost-beneficial after 1-3 year follow-up. Main limitation that may have contributed to absence of positive effects may be program failure, because interventions were not deployed as intended.

Psychological effects of the intensified follow-up of the CEAwatch trial after treatment for colorectal cancer

BACKGROUND

The aim of the study was to evaluate psychological effects of the state-of-art intensified follow-up protocol for colorectal cancer patients in the CEAwatch trial.

METHOD

At two time points during the CEAwatch trial questionnaires regarding patients' attitude towards follow-up, patients' psychological functioning and patients' experiences and expectations were sent to participants by post. Linear mixed models were fitted to assess the influences and secular trends of the intensified follow-up on patients' attitude towards follow-up and psychological functioning. As secondary outcome, odds ratios were calculated using ordinal logistic mixed model to compare patients' experiences to their expectations, as well as their experiences at two different time points.

RESULTS

No statistical significant effects of the intensified follow-up were found on patients' attitude towards the follow-up and psychological functioning variables. Patients had high expectations of the intensified follow-up and their experiences at the second time point were more positive compared to the scores at the first time point.

CONCLUSION

The intensified follow-up protocol posed no adverse effects on patients' attitude towards follow-up and psychological functioning. In general, patients were more nervous and anxious at the start of the new follow-up protocol, had high expectations of the new follow-up protocol and were troubled by the nuisances of the blood sample testing. As they spent more time in the follow-up and became more adapted to it, the nervousness and anxiety decreased and the preference for the frequent blood test became high in replacement of conversations with the doctors.

Survival analysis of the CEAwatch multicentre clustered randomized trial

BACKGROUND

The CEAwatch randomized trial showed that follow-up with intensive carcinoembryonic antigen (CEA) monitoring (CEAwatch protocol) was better than care as usual (CAU) for early postoperative detection of colorectal cancer recurrence. The aim of this study was to calculate overall survival (OS) and disease-specific survival (DSS).

METHODS

For all patients with recurrence, OS and DSS were compared between patients detected by the CEAwatch protocol versus CAU, and by the method of detection of recurrence, using Cox regression models.

RESULTS

Some 238 patients with recurrence were analysed (7·5 per cent); a total of 108 recurrences were detected by CEA blood test, 64 (55·2 per cent) within the CEAwatch protocol and 44 (41·9 per cent) in the CAU group (P = 0·007). Only 16 recurrences (13·8 per cent) were detected by patient self-report in the CEAwatch group, compared with 33 (31·4 per cent) in the CAU group. There was no significant improvement in either OS or DSS with the CEAwatch protocol compared with CAU: hazard ratio 0·73 (95 per cent 0·46 to 1·17) and 0·78 (0·48 to 1·28) respectively. There were no differences in survival when recurrence was detected by CT versus CEA measurement, but both of these methods yielded better survival outcomes than detection by patient self-report.

CONCLUSION

There was no direct survival benefit in favour of the intensive programme, but the CEAwatch protocol led to a higher proportion of recurrences being detected by CEA-based blood test and reduced the number detected by patient self-report. This is important because detection of recurrence by blood test was associated with significantly better survival than patient self-report, indirectly supporting use of the CEAwatch protocol.

Predictive performance of TPA testing for recurrent disease during follow-up after curative intent surgery for colorectal carcinoma

BACKGROUND

The aim of the present study was to investigate the predictive performance of serial tissue polypeptide antigen (TPA) testing after curative intent resection for detection of recurrence of colorectal malignancy.

METHODS

Serum samples were obtained in 572 patients from three different hospitals during follow-up after surgery. Test characteristics of serial TPA testing were assessed using a cut-off value of 75 U/L. The relation with American Joint Committee on Cancer stage and the potential additive value of tissue polypeptide antigen testing upon standard carcinoembryonic antigen (CEA) testing were investigated.

RESULTS

The area under the receiver operating characteristic curve of TPA for recurrent disease was 0.70, indicating marginal usefulness as a predictive test. Forty percent of cases that were detected by CEA testing would have been missed by TPA testing alone, whilst most cases missed by CEA were also not detected by TPA testing. In the subpopulation of patients with stage III disease predictive performance was good (area under the curve 0.92 within 30 days of diagnosing recurrent disease). In this group of patients, 86% of cases that were detected by CEA were also detected by TPA.

CONCLUSIONS

Overall, TPA is a relatively poor predictor for recurrent disease during follow-up. When looking at the specific subpopulation of patients with stage III disease predictive performance of TPA was good. However, TPA testing was not found to be superior to CEA testing in this specific subpopulation.

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

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.

Follow-up strategies for patients treated for non-metastatic colorectal cancer

BACKGROUND

It is common clinical practice to follow patients with colorectal cancer (CRC) for several years following their curative surgery or adjuvant therapy, or both. Despite this widespread practice, there is considerable controversy about how often patients should be seen, what tests should be performed, and whether these varying strategies have any significant impact on patient outcomes. This is the second update of a Cochrane Review first published in 2002 and first updated in 2007.

OBJECTIVES

To assess the effects of intensive follow-up for patients with non-metastatic colorectal cancer treated with curative intent.

SEARCH METHODS

For this update, we searched CENTRAL (2016, Issue 3), MEDLINE (1950 to May 20th, 2016), Embase (1974 to May 20th, 2016), CINAHL (1981 to May 20th, 2016), and Science Citation Index (1900 to May 20th, 2016). We also searched reference lists of articles, and handsearched the Proceedings of the American Society for Radiation Oncology (2011 to 2014). In addition, we searched the following trials registries (May 20th, 2016): ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform. We further contacted study authors. No language or publication restrictions were applied to the search strategies.

SELECTION CRITERIA

We included only randomised controlled trials comparing different follow-up strategies for participants with non-metastatic CRC treated with curative intent.

DATA COLLECTION AND ANALYSIS

Two authors independently determined trial eligibility, performed data extraction, and assessed methodological quality.

MAIN RESULTS

We studied 5403 participants enrolled in 15 studies. (We included two new studies in this second update.) Although the studies varied in setting (general practitioner (GP)-led, nurse-led, or surgeon-led) and "intensity" of follow-up, there was very little inconsistency in the results.Overall survival: we found no evidence of a statistical effect with intensive follow-up (hazard ratio (HR) 0.90, 95% confidence interval (CI) 0.78 to 1.02; I² = 4%; P = 0.41; high-quality evidence). There were 1098 deaths among 4786 participants enrolled in 12 studies.Colorectal cancer-specific survival: this did not differ with intensive follow-up (HR 0.93, 95% CI 0.78 to 1.12; I² = 0%; P = 0.45; moderate-quality evidence). There were 432 colorectal cancer deaths among 3769 participants enrolled in seven studies.Relapse-free survival: we found no statistical evidence of effect with intensive follow-up (HR 1.03, 95% CI 0.90 to 1.18; I² = 5%; P = 0.39; moderate-quality evidence). There were 1416 relapses among 5253 participants enrolled in 14 studies.Salvage surgery with curative intent: this was more frequent with intensive follow-up (risk ratio (RR) 1.98, 95% CI 1.53 to 2.56; I² = 31%; P = 0.14; high-quality evidence). There were 457 episodes of salvage surgery in 5157 participants enrolled in 13 studies.Interval (symptomatic) recurrences: these were less frequent with intensive follow-up (RR 0.59, 95% CI 0.41 to 0.86; I² = 66%; P = 0.007; moderate-quality evidence). Three hundred and seventy-six interval recurrences were reported in 3933 participants enrolled in seven studies.Intensive follow-up did not appear to affect quality of life, anxiety, nor depression (reported in three studies).Harms from colonoscopies did not differ with intensive follow-up (RR 2.08, 95% CI 0.11 to 40.17; moderate-quality evidence). In two studies, there were seven colonoscopic complications in 2112 colonoscopies.

AUTHORS' CONCLUSIONS

The results of our review suggest that there is no overall survival benefit for intensifying the follow-up of patients after curative surgery for colorectal cancer. Although more participants were treated with salvage surgery with curative intent in the intensive follow-up group, this was not associated with improved survival. Harms related to intensive follow-up and salvage therapy were not well reported.

A practical Bayesian stepped wedge design for community-based cluster-randomized clinical trials: The British Columbia Telehealth Trial

BACKGROUND

Many clinical trial designs are impractical for community-based clinical intervention trials. Stepped wedge trial designs provide practical advantages, but few descriptions exist of their clinical implementational features, statistical design efficiencies, and limitations.

OBJECTIVES

Enhance efficiency of stepped wedge trial designs by evaluating the impact of design characteristics on statistical power for the British Columbia Telehealth Trial.

METHODS

The British Columbia Telehealth Trial is a community-based, cluster-randomized, controlled clinical trial in rural and urban British Columbia. To determine the effect of an Internet-based telehealth intervention on healthcare utilization, 1000 subjects with an existing diagnosis of congestive heart failure or type 2 diabetes will be enrolled from 50 clinical practices. Hospital utilization is measured using a composite of disease-specific hospital admissions and emergency visits. The intervention comprises online telehealth data collection and counseling provided to support a disease-specific action plan developed by the primary care provider. The planned intervention is sequentially introduced across all participating practices. We adopt a fully Bayesian, Markov chain Monte Carlo-driven statistical approach, wherein we use simulation to determine the effect of cluster size, sample size, and crossover interval choice on type I error and power to evaluate differences in hospital utilization.

RESULTS

For our Bayesian stepped wedge trial design, simulations suggest moderate decreases in power when crossover intervals from control to intervention are reduced from every 3 to 2 weeks, and dramatic decreases in power as the numbers of clusters decrease. Power and type I error performance were not notably affected by the addition of nonzero cluster effects or a temporal trend in hospitalization intensity.

CONCLUSION/LIMITATIONS

Stepped wedge trial designs that intervene in small clusters across longer periods can provide enhanced power to evaluate comparative effectiveness, while offering practical implementation advantages in geographic stratification, temporal change, use of existing data, and resource distribution. Current population estimates were used; however, models may not reflect actual event rates during the trial. In addition, temporal or spatial heterogeneity can bias treatment effect estimates.

The analysis of terminal endpoint events in stepped wedge designs

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.

Design of trials for interrupting the transmission of endemic pathogens

Background

Many interventions against infectious diseases have geographically diffuse effects. This leads to contamination between arms in cluster-randomized trials (CRTs). Pathogen elimination is the goal of many intervention programs against infectious agents, but contamination means that standard CRT designs and analyses do not provide inferences about the potential of interventions to interrupt pathogen transmission at maximum scale-up.

Methods

A generic model of disease transmission was used to simulate infections in stepped wedge cluster-randomized trials (SWCRTs) of a transmission-reducing intervention, where the intervention has spatially diffuse effects. Simulations of such trials were then used to examine the potential of such designs for providing generalizable causal inferences about the impact of such interventions, including measurements of the contamination effects. The simulations were applied to the geography of Rusinga Island, Lake Victoria, Kenya, the site of the SolarMal trial on the use of odor-baited mosquito traps to eliminate Plasmodium falciparum malaria. These were used to compare variants in the proposed SWCRT designs for the SolarMal trial.

Results

Measures of contamination effects were found that could be assessed in the simulated trials. Inspired by analyses of trials of insecticide-treated nets against malaria when applied to the geography of the SolarMal trial, these measures were found to be robust to different variants of SWCRT design. Analyses of the likely extent of contamination effects supported the choice of cluster size for the trial.

Conclusions

The SWCRT is an appropriate design for trials that assess the feasibility of local elimination of a pathogen. The effects of incomplete coverage can be estimated by analyzing the extent of contamination between arms in such trials, and the estimates also support inferences about causality. The SolarMal example illustrates how generic transmission models incorporating spatial smoothing can be used to simulate such trials for a power calculation and optimization of cluster size and randomization strategies. The approach is applicable to a range of infectious diseases transmitted via environmental reservoirs or via arthropod vectors.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1378-1) contains supplementary material, which is available to authorized users.

Stepped wedge cluster randomised trials: a review of the statistical methodology used and available

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.

Sample size determinations for stepped-wedge clinical trials from a three-level data hierarchy perspective

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.

Use of an embedded, micro-randomised trial to investigate non-compliance in telehealth interventions

Background/aims:

Many types of telehealth interventions rely on activity from the patient in order to have a beneficial effect on their outcome. Remote monitoring systems require the patient to record regular measurements at home, for example, blood pressure, so clinicians can see whether the patient’s health changes over time and intervene if necessary. A big problem in this type of intervention is non-compliance. Most telehealth trials report compliance rates, but they rarely compare compliance among various options of telehealth delivery, of which there may be many. Optimising telehealth delivery is vital for improving compliance and, therefore, clinical outcomes. We propose a trial design which investigates ways of improving compliance. For efficiency, this trial is embedded in a larger trial for evaluating clinical effectiveness. It employs a technique called micro-randomisation, where individual patients are randomised multiple times throughout the study. The aims of this article are (1) to verify whether the presence of an embedded secondary trial still allows valid analysis of the primary research and (2) to demonstrate the usefulness of the micro-randomisation technique for comparing compliance interventions.

Methods:

Simulation studies were used to simulate a large number of clinical trials, in which no embedded trial was used, a micro-randomised embedded trial was used, and a factorial embedded trial was used. Each simulation recorded the operating characteristics of the primary and secondary trials.

Results:

We show that the type I error rate of the primary analysis was not affected by the presence of an embedded secondary trial. Furthermore, we show that micro-randomisation is superior to a factorial design as it reduces the variation caused by within-patient correlation. It therefore requires smaller sample sizes – our simulations showed a requirement of 128 patients for a micro-randomised trial versus 760 patients for a factorial design, in the presence of within-patient correlation.

Conclusion:

We believe that an embedded, micro-randomised trial is a feasible technique that can potentially be highly useful in telehealth trials.

Impact of a transition nurse program on the prevention of thirty-day hospital readmissions of elderly patients discharged from short-stay units: study protocol of the PROUST stepped-wedge cluster randomised trial

Background

In France, for patients aged 75 or older, it has been estimated that the hospital readmission rate within 30 days is 14 %, a quarter being avoidable. Some evidence suggests that interventions “bridging” the transition from hospital to home and involving a designated professional (usually nurses) are the most effective in reducing the risk of readmission, but the level of evidence of current studies is low. Our study aims to assess the impact of a care transition program from hospital to home for elderly admitted to short-stay units.

Methods

This is a multicentre, stepped-wedge cluster randomised trial.

The program will be implemented at three times of the transition: 1) during the patient’s stay in hospital: development of a discharge plan, creation of a transitional care file, and notification of the primary care physician about inpatient care and hospital discharge by the transition nurse; 2) on the day of discharge: meeting between the transition nurse and the patient to review the follow-up recommendations; and 3) for 4 weeks after discharge: follow-up by the transition nurse.

The primary outcome is the 30-day unscheduled hospital readmission or emergency visit rate after the index hospital discharge.

The patients enrolled will be aged 75 or older, hospitalized in an acute care geriatric unit, and at risk of hospital readmission or an emergency visit after returning home.

In all, 630 patients will be included over a 14-month period. Data analysis will be blinded to allocation, but due to the nature of the intervention, physicians and patients will not be blinded.

Discussion

Our study makes it possible to evaluate the specific effect of a bridging intervention involving a designated professional intervening before, during, and after hospital discharge.

The strengths of the study design are methodological and practical. It permits the estimation of the intervention effect using between- and within-cluster comparisons; the study of the fluctuations in unscheduled hospital readmission or emergency visit rates; the participation of all clusters in the intervention condition; the implementation of the intervention in each cluster successively.

Trial Registration

This study has been registered as a cRCT at clinicaltrials.gov (identifier: NCT02421133). Registered 9 March 2015.

Cost-effectiveness of a carcinoembryonic antigen (CEA) based follow-up programme for colorectal cancer (the CEA Watch trial)

AIM

The study CEA Watch (Netherlands Trial Register 2182) has shown that an intensified follow-up schedule with more frequent carcinoembryonic antigen (CEA) measurements but fewer outpatient visits detects more curable recurrences compared with the usual follow-up protocol in colorectal cancer (CRC) patients. The aim of the study was to compare the cost and cost-effectiveness between various follow-up programmes.

METHOD

In total, 3223 patients with stage I-III CRC were followed between October 2010 and October 2012. Direct medical costs were calculated per patient adding the costs for all visits, CEA measurements and imaging. Productivity losses and travel expenses were calculated using answers from questionnaires. The cost-effectiveness displayed the additional costs per additional patient with recurrent disease and used an incremental cost-effectiveness ratio (ICER) to compare them.

RESULTS

The mean yearly cost per patient was €548 in the intensified protocol and €497 in the control protocol. The ICER was €94 (95% CI €76-€157) per cent; to detect one additional patient with a recurrence in the intervention protocol compared with the control protocol would require an additional €9400. For curable recurrences, the ICER was €607 (95% CI €5695-€5728). Annual patient-reported costs were €509 per year in the intervention protocol and €488 in the control protocol.

CONCLUSION

The current study demonstrates that the direct medical and patient-reported cost of a newly introduced, safe and effective way of CRC follow-up was comparable to that of standard care. The ICER per curable recurrence was considered acceptably low.

The need to balance merits and limitations from different disciplines when considering the stepped wedge cluster randomized trial design

Background

Various papers have addressed pros and cons of the stepped wedge cluster randomized trial design (SWD). However, some issues have not or only limitedly been addressed. Our aim was to provide a comprehensive overview of all merits and limitations of the SWD to assist researchers, reviewers and medical ethics committees when deciding on the appropriateness of the SWD for a particular study.

Methods

We performed an initial search to identify articles with a methodological focus on the SWD, and categorized and discussed all reported advantages and disadvantages of the SWD. Additional aspects were identified during multidisciplinary meetings in which ethicists, biostatisticians, clinical epidemiologists and health economists participated. All aspects of the SWD were compared to the parallel group cluster randomized design. We categorized the merits and limitations of the SWD to distinct phases in the design and conduct of such studies, highlighting that their impact may vary depending on the context of the study or that benefits may be offset by drawbacks across study phases. Furthermore, a real-life illustration is provided.

Results

New aspects are identified within all disciplines. Examples of newly identified aspects of an SWD are: the possibility to measure a treatment effect in each cluster to examine the (in)consistency in effects across clusters, the detrimental effect of lower than expected inclusion rates, deviation from the ordinary informed consent process and the question whether studies using the SWD are likely to have sufficient social value. Discussions are provided on e.g. clinical equipoise, social value, health economical decision making, number of study arms, and interim analyses.

Conclusions

Deciding on the use of the SWD involves aspects and considerations from different disciplines not all of which have been discussed before. Pros and cons of this design should be balanced in comparison to other feasible design options as to choose the optimal design for a particular intervention study.

Intensified follow-up in colorectal cancer patients using frequent Carcino-Embryonic Antigen (CEA) measurements and CEA-triggered imaging: Results of the randomized "CEAwatch" trial

AIM

The value of frequent Carcino-Embryonic Antigen (CEA) measurements and CEA-triggered imaging for detecting recurrent disease in colorectal cancer (CRC) patients was investigated in search for an evidence-based follow-up protocol.

METHODS

This is a randomized-controlled multicenter prospective study using a stepped-wedge cluster design. From October 2010 to October 2012, surgically treated non-metastasized CRC patients in follow-up were followed in eleven hospitals. Clusters of hospitals sequentially changed their usual follow-up care into an intensified follow-up schedule consisting of CEA measurements every two months, with imaging in case of two CEA rises. The primary outcome measures were the proportion of recurrences that could be treated with curative intent, recurrences with definitive curative treatment outcome, and the time to detection of recurrent disease.

RESULTS

3223 patients were included; 243 recurrences were detected (7.5%). A higher proportion of recurrences was detected in the intervention protocol compared to the control protocol (OR = 1.80; 95%-CI: 1.33-2.50; p = 0.0004). The proportion of recurrences that could be treated with curative intent was higher in the intervention protocol (OR = 2.84; 95%-CI: 1.38-5.86; p = 0.0048) and the proportion of recurrences with definitive curative treatment outcome was also higher (OR = 3.12, 95%-CI: 1.25-6.02, p-value: 0.0145). The time to detection of recurrent disease was significantly shorter in the intensified follow-up protocol (HR = 1.45; 95%-CI: 1.08-1.95; p = 0.013).

CONCLUSION

The CEAwatch protocol detects recurrent disease after colorectal cancer earlier, in a phase that a significantly higher proportion of recurrences can be treated with curative intent.

Implementation of a stepped-wedge cluster randomized design in routine public health practice: design and application for a tuberculosis (TB) household contact study in a high burden area of Lima, Peru

Background

We designed a pragmatic stepped-wedge cluster randomized controlled trial in order to evaluate provider-initiated evaluation of household contacts (HCs) of smear positive tuberculosis (TB) cases within a routine TB program in Lima, Peru.

Methods/Design

National TB program (NTP) officers of San Juan de Lurigancho District (Lima, Peru) and university-based researchers jointly designed a pragmatic stepped-wedge cluster randomized trial design in order to evaluate a planned active case finding (ACF) program for all HCs of smear-positive TB cases in 34 district healthcare centres. Randomization of time to intervention initiation was stratified by health centre TB case rate. The ACF intervention included provider-initiated home visits of all new sputum smear positive TB patients in order to evaluate household contacts for active TB. Active TB was diagnosed using symptom screening, sputum screening, chest x-ray and clinical evaluation. Once initiated, ACF was provided by NTP staff and integrated into the routine DOTS TB program activities.

Discussion

This study protocol describes the pragmatic stepped-wedge cluster randomized trial of active household contact evaluations within an NTP. The stepped-wedge design met overlapping needs of local TB programmers and researchers to adequately evaluate the large-scale roll out of a new control program in a TB endemic setting. Multiple planning meetings were required to develop the necessary networks and in order to understand the operations, needs and goals of the NTP staff and researchers collaborating on this project. The advantages and challenges of using this study design in practice and within existing routine TB programs in a middle-income country context are discussed.

Trial registration

ClinicalTrials.gov NCT02174380. Registered 24 Jun 2014

A stepped wedge design for testing an effect of intranasal insulin on cognitive development of children with Phelan-McDermid syndrome: A comparison of different designs

This paper compares the power of the parallel group design, the matched-pairs design, and several options for the stepped wedge and delayed start designs for testing a possible effect of intranasal insulin with respect to placebo on developmental growth of children with a rare disorder like Phelan-McDermid syndrome. A subject-specific linear mixed effects model for the primary outcome developmental age in a longitudinal setting with five time points was assumed. Monte Carlo simulation studies with small sample sizes were applied since the rare disorder prohibits large trials. The stepped wedge designs, which were initially preferred for ethical reasons, appear to be competitive in power to other designs and were in some settings even the best. The assumed statistical model also demonstrates that all of the designs can be viewed as a stepped wedge or delayed treatment design. Our results show that the stepped wedge design is an appropriate alternative for randomized controlled trials on developmental growth with small numbers of participants under the formulated statistical conditions.