Consistency Of Treatment Effect Research Articles

Consistency between Treatment Effects on Clinical and Brain Atrophy Outcomes in Alzheimer’s Disease Trials

BackgroundLongitudinal changes in volumetric MRI outcome measures have been shown to correlate well with longitudinal changes in clinical instruments and have been widely used as biomarker outcomes in clinical trials for Alzheimer’s disease (AD). While instances of discordant findings have been noted in some trials, especially the recent amyloid-removing therapies, the overall relationship between treatment effects on brain atrophy and clinical outcomes, and how it might depend on treatment target or mechanism, clinical instrument or imaging variable is not yet clear.ObjectiveTo systematically assess the consistency and therapeutic class-dependence of treatment effects on clinical outcomes and on brain atrophy in published reports of clinical trials conducted in mild cognitive impairment (MCI) and/or AD.DesignQuantitative review of the published literature. The consistency of treatment effects on clinical and brain atrophy outcomes was assessed in terms of statistical agreement with hypothesized equal magnitude effects (e.g., 30% slowing of both) and nominal directional concordance, as a function of therapeutic class.SettingInterventional randomized clinical trials.ParticipantsMCI or AD trial participants.InterventionTreatments included were those that involved ingestion or injection of a putatively active substance into the body, encompassing both pharmacological and controlled dietary interventions.MeasurementsEach trial included in the analysis reported at least one of the required clinical outcomes (ADAS-Cog, CDR-SB or MMSE) and at least one of the required imaging outcomes (whole brain, ventricular or hippocampal volume).ResultsData from 35 trials, comprising 185 pairwise comparisons, were included. Overall, the 95% confidence bounds overlapped with the line of identity for 150/185 (81%) of the imaging-clinical variable pairs. The greatest proportion of outliers was found in trials of anti-amyloid antibodies that have been shown to dramatically reduce the level of PET-detectable amyloid plaques, for which only 13/33 (39%) of observations overlapped the identity line. A Deming regression calculated using all data points yielded a slope of 0.54, whereas if data points from the amyloid remover class were excluded, the Deming regression line had a slope of 0.92. Directional discordance of treatment effects was also most pronounced for the amyloid-removing class, and for comparisons involving ventricular volume.ConclusionOur results provide a frame of reference for the interpretation of clinical and brain atrophy results from future clinical trials and highlight the importance of mechanism of action in the interpretation of imaging results.

Consistency of Treatment Effect with Aflibercept by Baseline Factors in PANORAMA

More eyes treated with intravitreal aflibercept in PANORAMA achieved ≥2-step improvement in DRSS score and fewer developed vision-threatening complications and/or CI-DME versus sham, consistently across all baseline demographic and disease characteristic subgroups assessed.

OC-01 (Varenicline Solution) Nasal Spray for the Treatment of Dry Eye Disease Signs and Symptoms in Subjects with Autoimmune Disease: Integrated Data from ONSET-1 and ONSET-2.

We evaluate the treatment effect of OC-01 (varenicline solution) nasal spray (VNS) in dry eye disease (DED) subjects from two randomized trials who self-reported autoimmune disease (AID). Post hoc subgroup analysis of subjects reporting a history of AID from the integrated OC-01 VNS 0.03 or 0.06 mg and vehicle control (VC) treatment groups of the ONSET-1 and ONSET-2 trials. Mean change in Schirmer test with anesthesia score (STS, mm) and Eye Dryness Score (EDS) from baseline to 28 days was compared between OC-01 VNS and VC groups. Consistency of treatment effect in subjects with and without AID was evaluated using treatment-subgroup interaction terms in ANCOVA models for mean changes from baseline STS and EDS, and in a logistic regression model for proportion achieving ≥10 mm STS improvement. Of the 891 participants, 31 reported comorbid AID. In all models, the treatment-subgroup interaction terms were not significant (p>0.05), indicating consistency of therapeutic effect of OC-01 VNS in subjects with and without AID. In subjects with AID, the treatment difference for STS was 11.8 mm and -9.3 for EDS and difference for proportion of subjects with ≥10 mm STS improvement was 61.1%. The most common adverse event was sneeze (82-84%), graded as mild by 98% of subjects. OC-01 VNS demonstrated consistency in improving both tear production and patient-reported symptoms in subjects with AID, consistent with pivotal ONSET-1 and 2 trial results. Further investigation is warranted, and results may further support use of OC-01 VNS for DED in AID patients.

Does Menopausal Status Affect Dry Eye Disease Treatment Outcomes with OC-01 (Varenicline Solution) Nasal Spray? A PostHoc Analysis of ONSET-1 and ONSET-2 Clinical Trials.

This study sought to compare the efficacy of OC-01 (varenicline solution) nasal spray for treatment of dry eye disease (DED) in postmenopausal women (PM+) versus women who were not postmenopausal (PM-). This was a posthoc subgroup analysis of data integrated from two prior randomized controlled clinical trials, ONSET-1 and ONSET-2. Women randomized to treatment with OC-01 (varenicline solution) nasal spray 0.03mg or vehicle control (VC) whose self-reported menopausal status (PM+ versus PM-) was known were included. Outcomes included the treatment difference (the OC-01 [varenicline solution] nasal spray change from baseline [CFB] minus VC CFB) in Schirmer test score (STS, mm) with anesthesia and the eye dryness score (EDS) measured on a 100-mm visual analog scale (0 = no discomfort, 100 = maximal discomfort). Least-squares mean treatment differences were derived from analysis of covariance (ANCOVA) models. Overall, 449 female participants in the ONSET-1 and ONSET-2 trials randomized to the OC-01 (varenicline solution) nasal spray 0.03mg or VC groups were included in this analysis. The treatment-menopausal status interaction terms in the STS and EDS ANCOVA and logistic regression models were not statistically significant (p > 0.05), indicating consistency of treatment effect between the PM- and PM+ groups. The treatment difference in STS was similar in the PM- and PM+ groups (6.7 and 5.5mm, respectively). The treatment difference in EDS was similar in the PM- and PM+ groups (- 5.5 and - 4.1, respectively). OC-01 (varenicline solution) nasal spray demonstrated similar efficacy in promoting natural tear production and improving symptoms in both PM- and PM+ groups. As menopausal-related hormonal changes may be associated with more severe DED, these results may support OC-01 (varenicline solution) nasal spray as an effective treatment for DED in women regardless of presenting menopausal status. Posthoc subgroup analysis of data integrated from ONSET-1 (ClinicalTrials.gov identifier NCT03636061) and ONSET-2 (ClinicalTrials.gov identifier NCT04036292).

The Friends of Cancer Research Real-World Data Collaboration Pilot 2.0: Methodological Recommendations from Oncology Case Studies.

The purpose of this study was to evaluate the potential collective opportunities and challenges of transforming real‐world data (RWD) to real‐world evidence for clinical effectiveness by focusing on aligning analytic definitions of oncology end points. Patients treated with a qualifying therapy for advanced non‐small cell lung cancer in the frontline setting meeting broad eligibility criteria were included to reflect the real‐world population. Although a trend toward improved outcomes in patients receiving PD‐(L)1 therapy over standard chemotherapy was observed in RWD analyses, the magnitude and consistency of treatment effect was more heterogeneous than previously observed in controlled clinical trials. The study design and analysis process highlighted the identification of pertinent methodological issues and potential innovative approaches that could inform the development of high‐quality RWD studies.

Change in HbA1c Across the Baseline HbA1c Range in Type 2 Diabetes Patients Receiving Once-Weekly Dulaglutide Versus Other Incretin Agents.

IntroductionThis exploratory post hoc analysis investigated the relative changes in glycated haemoglobin (HbA1c) in patients with type 2 diabetes mellitus (T2DM) treated with dulaglutide versus active comparators across a continuous range of baseline HbA1c values using data from three phase III randomised controlled trials.MethodsData from patients receiving once-weekly dulaglutide 0.75 and 1.5 mg, once-daily sitagliptin 100 mg, once-daily liraglutide 1.8 mg or twice-daily exenatide 10 μg in the intent-to-treat populations in the AWARD-5, AWARD-6 and AWARD-1 trials were analysed using last observation carried forward analysis of covariance. Starting with the predefined statistical model from each study, the type of association between HbA1c baseline and change at 26 weeks was modelled. Consistency of treatment effect was assessed via treatment-by-baseline HbA1c interaction terms.ResultsImprovements in HbA1c occurred in all treatment groups across the entire baseline HbA1c range. The relationship between HbA1c baseline and magnitude of change was linear in all treatment groups, with greater reductions in patients with higher baseline HbA1c values. Across the continuum of baseline HbA1c values, patients treated with dulaglutide 1.5 mg achieved a similar mean HbA1c reduction to patients receiving liraglutide 1.8 mg and a greater reduction than patients receiving twice-daily exenatide or sitagliptin. In AWARD-5, the treatment-by-baseline HbA1c interaction P value (0.001) demonstrated progressively greater HbA1c reduction in dulaglutide-treated compared with sitagliptin-treated patients as baseline HbA1c increased.ConclusionOur results suggest that dulaglutide is an appropriate therapeutic option for patients with T2DM across a wide range of baseline HbA1c values, including those with poor metabolic control.FundingEli Lilly and Company.Plain Language SummaryPlain language summary available for this article.Electronic Supplementary MaterialThe online version of this article (10.1007/s13300-019-0625-3) contains supplementary material, which is available to authorized users.

Mortality after coronary artery bypass grafting versus percutaneous coronary intervention with stenting for coronary artery disease: a pooled analysis of individual patient data

Numerous randomised trials have compared coronary artery bypass grafting (CABG) with percutaneous coronary intervention (PCI) for patients with coronary artery disease. However, no studies have been powered to detect a difference in mortality between the revascularisation strategies. We did a systematic review up to July 19, 2017, to identify randomised clinical trials comparing CABG with PCI using stents. Eligible studies included patients with multivessel or left main coronary artery disease who did not present with acute myocardial infarction, did PCI with stents (bare-metal or drug-eluting), and had more than 1 year of follow-up for all-cause mortality. In a collaborative, pooled analysis of individual patient data from the identified trials, we estimated all-cause mortality up to 5 years using Kaplan-Meier analyses and compared PCI with CABG using a random-effects Cox proportional-hazards model stratified by trial. Consistency of treatment effect was explored in subgroup analyses, with subgroups defined according to baseline clinical and anatomical characteristics. We included 11 randomised trials involving 11 518 patients selected by heart teams who were assigned to PCI (n=5753) or to CABG (n=5765). 976 patients died over a mean follow-up of 3·8 years (SD 1·4). Mean Synergy between PCI with Taxus and Cardiac Surgery (SYNTAX) score was 26·0 (SD 9·5), with 1798 (22·1%) of 8138 patients having a SYNTAX score of 33 or higher. 5 year all-cause mortality was 11·2% after PCI and 9·2% after CABG (hazard ratio [HR] 1·20, 95% CI 1·06-1·37; p=0·0038). 5 year all-cause mortality was significantly different between the interventions in patients with multivessel disease (11·5% after PCI vs 8·9% after CABG; HR 1·28, 95% CI 1·09-1·49; p=0·0019), including in those with diabetes (15·5% vs 10·0%; 1·48, 1·19-1·84; p=0·0004), but not in those without diabetes (8·7% vs 8·0%; 1·08, 0·86-1·36; p=0·49). SYNTAX score had a significant effect on the difference between the interventions in multivessel disease. 5 year all-cause mortality was similar between the interventions in patients with left main disease (10·7% after PCI vs 10·5% after CABG; 1·07, 0·87-1·33; p=0·52), regardless of diabetes status and SYNTAX score. CABG had a mortality benefit over PCI in patients with multivessel disease, particularly those with diabetes and higher coronary complexity. No benefit for CABG over PCI was seen in patients with left main disease. Longer follow-up is needed to better define mortality differences between the revascularisation strategies. None.

Practical Recommendations for Regional Consistency Evaluation in Multi-Regional Clinical Trials with Different Endpoints

ABSTRACTIn recent years, there is an increasing trend to conduct multi-regional clinical trials (MRCT) for drug development in pharmaceutical industry. A carefully designed MRCT could be used in supporting the new drug's approval in different regions simultaneously. The primary objective of an MRCT is to investigate the drug's overall efficacy across regions while also assessing the drug's performance in some specific regions. In order to claim the study drug's efficacy and get drug approval in some specific region(s), the local regulatory authority may require the sponsors to provide evidence of consistency in the treatment effect between the overall patient population and the local region. Usually, the regional specific consistency requirement needs to be pre-specified before the study conduct and the consistency in treatment effect between the region(s) of interest and overall population will be evaluated at the final analysis. In this article, we evaluate the consistency requirements in multi-regional clinical trials for different endpoints, that is, continuous, binary, and survival endpoints. We also compare the different consistency requirements of the same endpoint/measurement if multiple consistency requirements are enforced and our recommendations for each endpoint/measurement will be made based on the comprehensive consideration.

Sample size determination for a specific region in multiregional clinical trials with multiple co-primary endpoints.

Recently, multi-regional clinical trials (MRCTs), which incorporate subjects from many countries/regions around the world under the same protocol, have been widely conducted by many global pharmaceutical companies. The objective of such trials is to accelerate the development process for a drug and shorten the drug’s approval time in key markets. Several statistical methods have been purposed for the design and evaluation of MRCTs, as well as for assessing the consistency of treatment effects across all regions with one primary endpoint. However, in some therapeutic areas (e.g., Alzheimer’s disease), the clinical efficacy of a new treatment may be characterized by a set of possibly correlated endpoints, known as multiple co-primary endpoints. In this paper, we focus on a specific region and establish three statistical criteria for evaluating consistency between the specific region and overall results in MRCTs with multiple co-primary endpoints. More specifically, two of those criteria are used to assess whether the treatment effect in the region of interest is as large as that of the other regions or of the regions overall, while the other criterion is used to assess the consistency of the treatment effect of the specific region achieving a pre-specified threshold. The sample size required for the region of interest can also be evaluated based on these three criteria.

Functional lesional neurosurgery for tremor—a protocol for a systematic review and meta-analysis

IntroductionThe recent introduction of incision-less lesional neurosurgery using Gamma Knife and MRI-guided focused ultrasound has revived interest in lesional treatment options for tremor disorders. Preliminary literature researches reveal that the...

Unified additional requirement in consideration of regional approval for multiregional clinical trials

ABSTRACTTo speed up the process of bringing a new drug to the market, more and more clinical trials are being conducted simultaneously in multiple regions. After demonstrating the overall drug’s efficacy across regions, the regulatory and drug sponsor may also want to assess the drug’s effect in specific region(s). Most of the recent approaches imposed a uniform criterion to assess the consistency of treatment effects between the interested region(s) and the entire study population regardless of the number of regions in multiregional clinical trials (MRCT). As a result, the needed sample size to achieve the desired probability of satisfying the regional requirement could be huge and implausible for the trial sponsors to implement.In this paper, we propose a unified additional requirement for regional approval by differing the parameters in the additional requirement depending on the number of planned regions. In particular, the values of the parameters are determined by a reasonable sample size increase with the desired probability satisfying the additional requirement. Considering the practicality of the global trial or sample size increase, we recommend specific values of the parameters for a different number of planned regions. We also introduce the assurance probability curve to evaluate the performance of different regional requirements.

Stability and Consistency of Treatment Effect With Liposomal Amikacin for Inhalation (LAI) as Add-on Therapy in Patients With Pulmonary Nontuberculous Mycobacterial (PNTM) Infection

Stability and Consistency of Treatment Effect With Liposomal Amikacin for Inhalation (LAI) as Add-on Therapy in Patients With Pulmonary Nontuberculous Mycobacterial (PNTM) Infection

Consistency of treatment effect across the range of baseline HbA1c in patients with type 2 diabetes mellitus (T2DM) treated with once-weekly dulaglutide or comparators in AWARD-1, -5 and -6

Objective: To characterise the relative effects of once-weekly dulaglutide (DU) and active comparators on change in HbA1c across the continuous range of baseline HbA1c values.

Statistical Considerations on Subgroup Analysis in Clinical Trials

The objective of subgroup analysis of a clinical trial is to investigate consistency or heterogeneity of the treatment effect across subgroups, defined based on background characteristics. As such, subgroup analysis plays an essential role in the interpretation of the clinical trial findings. Consistency of treatment effect across trial subgroups indicates that the average treatment effect is in general applicable regardless of the specific background characteristics. Substantial heterogeneity in treatment effect may be indicative that treatment benefit pertains only to a subset of the population. However, heterogeneity in the observed treatment effect across subgroups can arise due to chance as a result of partitioning the population into several subgroups. Furthermore, as it is known, clinical trials are generally not powered for detecting heterogeneity, thus statistical tests may miss detection of existing heterogeneity due to low power. In this article, we aim to: (i) outline the major issues underlying subgroup analysis in clinical trials and provide general statistical guidance for interpretation of its findings, (ii) provide statistical perspectives on the design and analysis of a clinical trial that aims for establishing efficacy in a targeted subgroup along with that of its overall population, and (iii) highlight some of the underlying assumptions and issues relevant to Bayesian subgroup analysis, subgroup considerations for noninferiority trials, personalized medicine, subgroup misclassification, and finally, subgroup analysis for safety assessment.

Glomerular filtration rate decline as a surrogate end point in kidney disease progression trials

Chronic kidney disease (CKD) is strongly associated with increased risks of progression to end-stage kidney disease (ESKD) and mortality. Clinical trials evaluating CKD progression commonly use a composite end point of death, ESKD or serum creatinine doubling. However, due to low event rates, such trials require large sample sizes and long-term follow-up for adequate statistical power. As a result, very few interventions targeting CKD progression have been tested in randomized controlled trials. To overcome this problem, the National Kidney Foundation and Food and Drug Administration conducted a series of analyses to determine whether an end point of 30 or 40% decline in estimated glomerular filtration rate (eGFR) over 2-3 years can substitute for serum creatinine doubling in the composite end point. These analyses demonstrated that these alternate kidney end points were significantly associated with subsequent risks of ESKD and death. However, the association between, and consistency of treatment effects on eGFR decline and clinical end points were influenced by baseline eGFR, follow-up duration and acute hemodynamic effects. The investigators concluded that a 40% eGFR decline is broadly acceptable as a kidney end point across a wide baseline eGFR range and that a 30% eGFR decline may be acceptable in some situations. Although these alternate kidney end points could potentially allow investigators to conduct shorter duration clinical trials with smaller sample sizes thereby generating evidence to guide clinical decision-making in a timely manner, it is uncertain whether these end points will improve trial efficiency and feasibility. This review critically appraises the evidence, strengths and limitations pertaining to eGFR end points.

Effects of lanreotide autogel/depot (LAN) in pancreatic neuroendocrine tumors (pNETs): A subgroup analysis from the CLARINET study.

233 Background: The prognosis for patients with metastatic pNETs is generally poor and current treatment options can be complicated by safety considerations. In CLARINET, progression-free survival (PFS) was significantly prolonged with the somatostatin analog LAN 120 mg vs. placebo (PBO) in patients with metastatic grade 1 or 2 (Ki-67 <10%) non-functioning enteropancreatic NETs (hazard ratio [HR] for progressive disease [PD]/death: 0.47 [95% CI: 0.30, 0.73]. Here, we more fully characterize treatment effects in the pNET subgroup. Methods: CLARINET was a 96-week randomized double-blind trial. Patients received LAN 120 mg or PBO every 4 weeks, administered by deep s.c. injection (NCT00353496). Subgroup analyses were undertaken to investigate only the consistency of treatment effects as the study was not otherwise designed or powered for such analyses. Results: 91 patients with pNETs received LAN (n=42) or PBO (n=49). At baseline, mean age was 64 years in both groups; overall, 37% had hepatic tumor loads >25%, 95% had stable disease, 77% had received no previous treatment, and 38% had had previous surgery on the tumor. Median PFS in the pNET subgroup was not reached at study end with LAN vs. 12.1 months [95% CI: 9.4, 18.3] with PBO (HR for PD/death: 0.58 [0.32, 1.04]). (Median PFS for LAN at first planned analysis in the open-label extension study was 29.7 months [12.0, 32.4].) The incidence of adverse events (AEs) in the core study was 88% with both LAN and PBO, and the most common AE was diarrhea (LAN, 43%; PBO, 37%). Treatment-related AEs occurred in 55% of the LAN group and 24% of the PBO group. Serious AEs (SAEs) occurred in 29% vs. 43%, respectively; only three of these patients had treatment-related SAEs (two with LAN, one with PBO). Two patients in each group had AEs leading to withdrawal. Conclusions: The evidence in the pNET subgroup suggesting antitumor effects with LAN together with the favorable long-term safety profile support a positive benefit:risk profile for LAN as a first-line treatment for pNETs. Clinical trial information: NCT00353496.

Effects of lanreotide autogel/depot (LAN) in patients with neuroendocrine tumors (NETs) age 65 or younger versus older than age 65: Subgroup analyses from the CLARINET study.

367 Background: The somatostatin analog lanreotide Autogel 120 mg significantly prolonged progression-free survival (PFS) vs. placebo (PBO) in patients with metastatic grade 1 or 2 (Ki-67 <10%) non-functioning enteropancreatic NETs (hazard ratio [HR] for progressive disease [PD]/death: 0.47 [95% CI: 0.30, 0.73]). The large size of the trial (n=204) affords an opportunity to examine treatment effects within subgroups of particular interest. Here, we compare PFS and safety data for patients aged ≤65 years vs. aged >65 years. Methods: In this 96-week randomized double-blind trial, patients received LAN 120 mg or PBO every 4 weeks by deep s.c. injection (NCT00353496). Subgroup analyses were undertaken to investigate only the consistency of treatment effects as the study was not otherwise designed or powered for such analyses. Results: Median age (range) was 57 years (30, 65) for thegroup aged ≤65 years and 71 years (66, 92) for the group aged >65 years. Other baseline characteristics were similar between age groups, including tumor origins (≤65 years: pancreatic 43%, midgut 34%; >65 years: pancreatic 46%, midgut 38%) and hepatic tumor loads (>25%: 30% and 37% for ≤65 and >65 years, respectively). Disease was predominantly stable at baseline (94% vs. 98%, respectively). Therapeutic effects of LAN on PFS were similar for the age groups and there were no consistent differences in tolerabilities between age groups (Table). The most common AE was diarrhea irrespective of age and treatment (≤65 years: LAN 36%, PBO 32%; >65 years: LAN 33%, PBO 40%). Conclusions: The treatment effect with LAN in terms of PFS was consistent across age groups and LAN tolerability/safety was favorable in both cases. Clinical trial information: NCT00353496. [Table: see text]

Sample Size Estimation of Multiregional Clinical Trials with Heterogeneous Variability Across Regions

In recent years, global collaboration has become a conventional strategy for new drug development. To accelerate the development process and shorten approval time, the design of multiregional clinical trials (MRCTs) incorporates subjects from many countries around the world under the same protocol. After showing the overall efficacy of a drug in all global regions, one can also simultaneously evaluate the possibility of applying the overall trial results to all regions and subsequently support drug registration in each of them. Several statistical methods have been proposed for the design and evaluation of MRCTs. Most of these approaches, however, assume a common variability of the primary endpoint across regions. In practice, this assumption may not be true, due to differences across regions (e.g., differences in ethnic factors and/or medical culture/practice). In this article, we use a random-effect model for modeling heterogeneous variability across regions for the design and evaluation of MRCTs. We also address consideration on the determination of the number of subjects in a specific region to establish the consistency of treatment effects between the specific region and the entire group.

Graphical assessment of consistency in treatment effect among countries in multi-regional clinical trials

One key objective of a multi-regional clinical trial (MRCT) is to use the trial results to 'bridge' from the global level to local region in support of local registrations. However, data from each individual country are typically limited and the large number of countries will increase the chance of false positive findings. Graphical tools to facilitate identification of potential outlying countries could be useful for country-level assessment. Existing methods such as funnel plot and expected range of treatment effect can substantially increase the false positive rate. The expected range approach can also have a very low power when there are a large number of small countries, which is typical in a MRCT. In this article, we apply normal probability plots, commonly used as a diagnostic tool in linear regression analysis, to assess the differences among countries. Evidence of possible inconsistency, which incorporates both the estimated treatment effect and sample size, is plotted against its expected order statistic. A simulation study is conducted to assess the impact of the negative correlation among residuals due to unequal sample sizes among countries and the performance of the proposed methods compared to existing approaches. The proposed methods tend to have a balanced consideration with substantially smaller false positive rate and reasonable probability to identify outlying countries in realistic scenarios. While much lower than that of commonly used methods, the false positive rates of the proposed methods are not strictly controlled. This may be acceptable for these graphical tools with intention to flag potential outliers for investigation. We recommend routine use of normal probability plots in MRCTs as a tool to identify potential outliers. If the normal probability plot is approximately linear but has heavy tails with a few outlying countries, these potential outliers should be examined carefully to understand the possible reasons.

Qualitative Consistency of Treatment Effects in Multiregional Clinical Trials

Consistency of treatment effects across different regions in multiregional clinical trials (MRCTs) has been an important question for the regulatory authorities. Many consistency definitions are proposed in literature. One of the definitions of consistency is expressed as qualitative consistency, whereas inconsistency is defined as qualitative treatment by region interaction. This article focuses on the qualitative consistency and extends Gail-Simon and Sasabuchi's one-sided multivariate likelihood ratio tests. Simulations are used to evaluate operating characteristics of these qualitative consistency assessment approaches. For a given number of regions, the guideline for setting significance level, and consistency cut-off are explored.