A pragmatic group sequential, placebo-controlled, randomised trial to determine the effectiveness of glyceryl trinitrate for retained placenta (GOT-IT): a study protocol.

INTRODUCTION: A retained placenta is diagnosed when the placenta is not delivered following delivery of the baby. It is a major cause of postpartum haemorrhage and treated by the operative procedure of manual removal of placenta (MROP). METHODS AND ANALYSIS: The aim of this pragmatic, randomised, placebo-controlled, double-blind UK-wide trial, with an internal pilot and nested qualitative research to adjust strategies to refine delivery of the main trial, is to determine whether sublingual glyceryl trinitrate (GTN) is (or is not) clinically and cost-effective for (medical) management of retained placenta. The primary clinical outcome is need for MROP, defined as the placenta remaining undelivered 15 min poststudy treatment and/or being required within 15 min of treatment due to safety concerns. The primary safety outcome is measured blood loss between administration of treatment and transfer to the postnatal ward or other clinical area. The primary patient-sided outcome is satisfaction with treatment and a side effect profile. The primary economic outcome is net incremental costs (or cost savings) to the National Health Service of using GTN versus standard practice. Secondary outcomes are being measured over a range of clinical and economic domains. The primary outcomes will be analysed using linear models appropriate to the distribution of each outcome. Health service costs will be compared with multiple trial outcomes in a cost-consequence analysis of GTN versus standard practice. ETHICS AND DISSEMINATION: Ethical approval has been obtained from the North-East Newcastle & North Tyneside 2 Research Ethics Committee (13/NE/0339). Dissemination plans for the trial include the Health Technology Assessment Monograph, presentation at international scientific meetings and publication in high-impact, peer-reviewed journals. TRIAL REGISTRATION NUMBER: ISCRTN88609453; Pre-results.

Investigating the relationship between predictability and imbalance in minimisation: a simulation study.

BACKGROUND: The use of restricted randomisation methods such as minimisation is increasing. This paper investigates under what conditions it is preferable to use restricted randomisation in order to achieve balance between treatment groups at baseline with regard to important prognostic factors and whether trialists should be concerned that minimisation may be considered deterministic. METHODS: Using minimisation as the randomisation algorithm, treatment allocation was simulated for hypothetical patients entering a theoretical study having values for prognostic factors randomly assigned with a stipulated probability. The number of times the allocation could have been determined with certainty and the imbalances which might occur following randomisation using minimisation were examined. RESULTS: Overall treatment balance is relatively unaffected by reducing the probability of allocation to optimal treatment group (P) but within-variable balance can be affected by any P <1. This effect is magnified by increased numbers of prognostic variables, the number of categories within them and the prevalence of these categories within the study population. CONCLUSIONS: In general, for smaller trials, probability of treatment allocation to the treatment group with fewer numbers requires a larger value P to keep treatment and variable groups balanced. For larger trials probability of allocation values from P = 0.5 to P = 0.8 can be used while still maintaining balance. For one prognostic variable there is no significant benefit in terms of predictability in reducing the value of P. However, for more than one prognostic variable, significant reduction in levels of predictability can be achieved with the appropriate choice of P for the given trial design.

Use of randomisation in clinical trials: a survey of UK practice.

BACKGROUND: In healthcare research the randomised controlled trial is seen as the gold standard because it ensures selection bias is minimised. However, there is uncertainty as to which is the most preferred method of randomisation in any given setting and to what extent more complex methods are actually being implemented in the field. METHODS: In this paper we describe the results of a survey of UK academics and publicly funded researchers to examine the extent of the use of various methods of randomisation in clinical trials. RESULTS: Trialists reported using simple randomisation, permuted blocks and stratification more often than more complex methods such as minimisation. Most trialists believed that simple randomisation is suitable for larger trials but there is a high probability of possible imbalance between treatment groups in small trials. It was thought that groups should be balanced at baseline to avoid imbalance and help face-validity. However, very few respondents considered that more complex methods offer any advantages. CONCLUSIONS: This paper demonstrates that for most UK trialists the preferred method of randomisation is using permuted blocks of varying random length within strata. This method eliminates the problem of predictability while maintaining balance across combinations of factors. If the number of prognostic factors is large, then minimisation can be used to provide treatment balance as well as balance over these factors. However, only those factors known to affect outcome should be considered.

Long-term follow-up for mortality and cancer in a randomized placebo-controlled trial of vitamin D(3) and/or calcium (RECORD trial).

CONTEXT: Vitamin D or calcium supplementation may have effects on vascular disease and cancer. OBJECTIVE: Our objective was to investigate whether vitamin D or calcium supplementation affects mortality, vascular disease, and cancer in older people. DESIGN AND SETTING: The study included long-term follow-up of participants in a two by two factorial, randomized controlled trial from 21 orthopedic centers in the United Kingdom. PARTICIPANTS: Participants were 5292 people (85% women) aged at least 70 yr with previous low-trauma fracture. INTERVENTIONS: Participants were randomly allocated to daily vitamin D(3) (800 IU), calcium (1000 mg), both, or placebo for 24-62 months, with a follow-up of 3 yr after intervention. MAIN OUTCOME MEASURES: All-cause mortality, vascular disease mortality, cancer mortality, and cancer incidence were evaluated. RESULTS: In intention-to-treat analyses, mortality [hazard ratio (HR) = 0.93; 95% confidence interval (CI) = 0.85-1.02], vascular disease mortality (HR = 0.91; 95% CI = 0.79-1.05), cancer mortality (HR = 0.85; 95% CI = 0.68-1.06), and cancer incidence (HR = 1.07; 95% CI = 0.92-1.25) did not differ significantly between participants allocated vitamin D and those not. All-cause mortality (HR = 1.03; 95% CI = 0.94-1.13), vascular disease mortality (HR = 1.07; 95% CI = 0.92-1.24), cancer mortality (HR = 1.13; 95% CI = 0.91-1.40), and cancer incidence (HR = 1.06; 95% CI = 0.91-1.23) also did not differ significantly between participants allocated calcium and those not. In a post hoc statistical analysis adjusting for compliance, thus with fewer participants, trends for reduced mortality with vitamin D and increased mortality with calcium were accentuated, although all results remain nonsignificant. CONCLUSIONS: Daily vitamin D or calcium supplementation did not affect mortality, vascular disease, cancer mortality, or cancer incidence.

The method of minimization for allocation to clinical trials. a review.

Minimization is a largely nonrandom method of treatment allocation for clinical trials. We conducted a systematic literature search to determine its advantages and disadvantages compared with other allocation methods. Minimization was originally proposed by Taves and by Pocock and Simon. The latter paper introduces a family of allocation methods of which Taves' method is the simplest example. Minimization aims to ensure treatment arms are balanced with respect to predefined patient factors as well as for the number of patients in each group. Further extensions of the method have also been proposed by other authors. Simulation studies show that minimization provides better balanced treatment groups when compared with restricted or unrestricted randomization and that it can incorporate more prognostic factors than stratified randomization methods such as permuted blocks within strata. Some more computationally complex methods may give an even better performance. Concerns over the use of minimization have centered on the fact that treatment assignments may be predicted with certainty in some situations and on the implications for the analysis methods used. It has been suggested that adjustment should always be made for minimization factors when analyzing trials where minimization is the allocation method used. The use of minimization may sometimes result in added organizational complexity compared with other methods. Minimization has been recommended by many commentators for use in clinical trials. Despite this it is still rarely used in practice. From the evidence presented in this review, we believe minimization to be a highly effective allocation method and recommend its wider adoption in the conduct of randomized controlled trials.