Dealing with Possible Baseline Inequalities Between Experimental Groups - The Case of Motor Learning

One important concept of experimental design is the random assignment of participants to experimental groups. This randomization process is used to prevent selection bias, as well as to provide a strong basis for a cause-and-effect relationship between the independent variable/s and the dependent variable/s. In small sample sizes, simple randomization may not provide equal groups at baseline for one or more of the variables, and therefore more restricted types of randomization, such as the stratified permuted-block randomization, can be used. A code was written to calculate the probability that simple randomization will not lead to equality between groups at baseline, and then an example of stratified permuted-block randomization was examined. The findings suggest that for certain variables that are commonly measured in experiments in motor learning, there is a relatively high probability that groups will not be equal at baseline after simple randomization. This observation reflects the small sample sizes usually found in the literature on motor learning. However, stratified permuted-block randomization does lead to greater equality among groups. Implications for researchers are discussed, and a flowchart is proposed that will allow researchers to decide whether to use simple or stratified randomization.

Rationale and design of the MarrowStim PAD Kit for the Treatment of Critical Limb Ischemia in Subjects with Severe Peripheral Arterial Disease (MOBILE) trial investigating autologous bone marrow cell therapy for critical limb ischemia

OBJECTIVE

Critical limb ischemia (CLI) continues to place a significant encumbrance on patients and the health care system as it progresses to limb loss and long-term disability. Traditional methods of revascularization offer a significant benefit; however, for one-third of CLI patients, these surgical options are not technically possible or patency is severely limited by disease burden (deemed "poor-option" for revascularization). In a previous phase I trial, we demonstrated intramuscular injection of concentrated bone marrow aspirate (cBMA) via MarrowStim (Zimmer Biomet, Warsaw, Ind) harvest is safe and may decrease major amputation in patients with CLI unfit for surgical revascularization. Therefore, we describe and rationalize the MarrowStim PAD Kit for the Treatment of Critical Limb Ischemia in Subjects with Severe Peripheral Arterial Disease (MOBILE) trial, a study geared to provide the pivotal proof of efficacy of cBMA in CLI.

METHODS

MOBILE is a multicenter, randomized, double-blind, placebo-controlled trial designed to assess the efficacy of intramuscular injections of cBMA in promoting amputation-free survival in patients with poor-option CLI. Patients (aged >21 years) with rest pain or tissue loss resulting from advanced peripheral arterial disease, as characterized by ankle-brachial index (<0.6), toe-brachial index (<0.4), or transcutaneous pressure of oxygen (<50 mm Hg), were eligible for inclusion if surgical revascularization was not possible secondary to advanced disease.

RESULTS

Treatment and 1-year follow-up of 152 patients enrolled in MOBILE are completed. Long-term follow-up is ongoing. Currently, we are in the process of unblinding the initial results for preliminary data analysis.

CONCLUSIONS

If successful, MOBILE could add definitive, high-quality evidence in support of cBMA for the treatment of poor-option CLI patients and provide an additional modality for patients who face amputation secondary to advanced limb ischemia.

OARSI Clinical Trials Recommendations: Design, conduct, and reporting of clinical trials for knee osteoarthritis

The goal of this document is to update the original OARSI recommendations specifically for the design, conduct, and reporting of clinical trials that target symptom or structure modification among individuals with knee osteoarthritis (OA). To develop recommendations for the design, conduct, and reporting of clinical trials for knee OA we initially drafted recommendations through an iterative process. Members of the working group included representatives from industry and academia. After the working group members reviewed a final draft, they scored the appropriateness for recommendations. After the members voted we calculated the median score among the nine members of the working group who completed the score. The document includes 25 recommendations regarding randomization, blocking and stratification, blinding, enhancing accuracy of patient-reported outcomes (PRO), selecting a study population and index knee, describing interventions, patient-reported and physical performance measures, structural outcome measures, biochemical biomarkers, and reporting recommendations. In summary, the working group identified 25 recommendations that represent the current best practices regarding clinical trials that target symptom or structure modification among individuals with knee OA. These updated recommendations incorporate novel technologies (e.g., magnetic resonance imaging (MRI)) and strategies to address the heterogeneity of knee OA.

CONSORT 2010 explanation and elaboration: updated guidelines for reporting parallel group randomised trials

Overwhelming evidence shows the quality of reporting of randomised controlled trials (RCTs) is not optimal. Without transparent reporting, readers cannot judge the reliability and validity of trial findings nor extract information for systematic reviews. Recent methodological analyses indicate that inadequate reporting and design are associated with biased estimates of treatment effects. Such systematic error is seriously damaging to RCTs, which are considered the gold standard for evaluating interventions because of their ability to minimise or avoid bias. A group of scientists and editors developed the CONSORT (Consolidated Standards of Reporting Trials) statement to improve the quality of reporting of RCTs. It was first published in 1996 and updated in 2001. The statement consists of a checklist and flow diagram that authors can use for reporting an RCT. Many leading medical journals and major international editorial groups have endorsed the CONSORT statement. The statement facilitates critical appraisal and interpretation of RCTs. During the 2001 CONSORT revision, it became clear that explanation and elaboration of the principles underlying the CONSORT statement would help investigators and others to write or appraise trial reports. A CONSORT explanation and elaboration article was published in 2001 alongside the 2001 version of the CONSORT statement. After an expert meeting in January 2007, the CONSORT statement has been further revised and is published as the CONSORT 2010 Statement. This update improves the wording and clarity of the previous checklist and incorporates recommendations related to topics that have only recently received recognition, such as selective outcome reporting bias. This explanatory and elaboration document-intended to enhance the use, understanding, and dissemination of the CONSORT statement-has also been extensively revised. It presents the meaning and rationale for each new and updated checklist item providing examples of good reporting and, where possible, references to relevant empirical studies. Several examples of flow diagrams are included. The CONSORT 2010 Statement, this revised explanatory and elaboration document, and the associated website (www.consort-statement.org) should be helpful resources to improve reporting of randomised trials.

Measuring sensorineural disability in preterm children using a public health screening strategy: a randomised controlled trial

AIM

To assess the efficacy of a preterm-targeted screening programme against the routine Australian National Health Medical Research Council (NHMRC) universal child health screening programme to detect disability in a general practice setting in children born < or =31 weeks gestation at 12-months of age.

METHODS

Multi-centred trial involving 202 preterm children randomised to receive the preterm-targeted or NHMRC programme. Primary outcome, correct identification of neurosensory disability by general practitioners assessed against gold standard paediatric assessments. Sensitivity analysis estimated interrater agreement and screening accuracy. Secondary outcomes, post natal depression (PND), parental stress, health service use, screening programme helpfulness and correct identification of levels of disability severity.

RESULTS

Of the 195 infants with data on the primary outcome in the preterm-targeted group, their general practitioners correctly identified the disability status of 61/93 (65.6%) children, as compared with 69/102 (67.6%) in the NHMRC group (odds ratios (OR) 0.91 95% confidence interval (CI) 0.50, 1.65). Responses where general practitioners were unsure of a child's disability status were coded as incorrect and not paired for sensitivity analysis. Sensitivity analysis for 180 diagnostic pairs showed fair interrater agreement for both groups (preterm-targeted k = 0.30 vs. NHMRC k = 0.29) with screening test results favouring the preterm-targeted group with greater sensitivity (73% vs. 33%) but lower specificity (70% vs. 92%) resulting in more over referrals (30% vs. 8%); however, these had a significantly lower mean Developmental Quotient (DQ) score compared with non-disabled children. PND scores were higher in preterm-targeted group (OR 1.33 95% CI 0.01, 2.66).

CONCLUSION

The preterm-targeted programme used by general practitioners: (i) did not improve overall identification of disability status compared to the NHMRC universal programme (Australian New Zealand Clinical Trails Registry number, ACTRN 12606000472572); however (ii) it did demonstrate greater efficacy as a screening tool in accurately identifying disabled children.

Recommendations for standardization of clinical trials with Allergen Specific Immunotherapy for respiratory allergy. A statement of a World Allergy Organization (WAO) taskforce

Specific Immunotherapy for respiratory allergy is used since about one century and there is now solid documentation of its efficacy. Nevertheless, the methods and experimental designs used in clinical trials are quite heterogeneous and there is no unanimously accepted methodological standard. Many studies are planned with study designs that may not confirm the clinical value of SIT as an effective treatment to reduce disease severity. To ensure that patients are treated based on sound scientific evidence and to minimize the risk of misusing limited financial resources for scientific studies, the World Allergy Organization (WAO) convened a group of experts to provide guidelines for the methodology of future immunotherapy studies. This document summarizes the recommendations for study design, patients' selection, appropriate outcomes and statistical treatment to be used in planning and performing clinical trials with specific immunotherapy.

Sublingual immunotherapy: efficacy--methodology and outcome of clinical trials

Using Medline we identified 39 placebo-controlled, double-blind sublingual immunotherapy (SLIT) studies providing symptom-medication score. These were retrospectively evaluated for evidence of clinical efficacy and quality of study presentation. Clinical efficacy was estimated according to statistical significance and graded as: unequivocal efficacy (statistically significant difference from placebo in both symptom and medication scores or the combined score), which was observed in 28% of studies, possible efficacy (significant improvement in either symptom or medication scores) seen in 33%, and no efficacy (no statistical difference between active treatment and the placebo group), as found in 38% of studies. Generally, studies were limited by the number of patients, showed a high frequency of withdrawals, a short duration of treatment, and insufficient data on randomization. The magnitude of efficacy additional to placebo treatment must be >20% in order to justify the treatment. This review concludes that future SLIT studies should be planned in accordance with international recommendations in order to be conclusive.

Assessment of QTc prolongation for non-cardiac-related drugs from a drug development perspective

It is increasingly likely that non-cardiac-related drugs will need to be routinely analyzed for their ability to prolong cardiac repolarization. This leads to potential problems for drug companies in general and statisticians in particular. A number of issues immediately arise in regard to answering the question, "Does drug X prolong cardiac repolarization?" These include identifying what is the desired outcome, what is the dependent variable, and what analysis method should be used. The purpose of this article is bring to to light some of the issues regarding the analysis of QTc data, the advantages and disadvantages of these analysis methods, and some general recommendations.

Testing for baseline balance in clinical trials

Once the data from a clinical trial are available for analysis it is common practice to carry out 'tests of baseline homogeneity' on prognostic covariates before proceeding to analyse the effects of treatment on outcome variables. It is argued that this practice is philosophically unsound, of no practical value and potentially misleading. Instead it is recommended that prognostic variables be identified in the trial-plan and fitted in an analysis of covariance regardless of their baseline distribution (statistical significance).