Regulatory Issues of Platform Trials: Learnings from EU-PEARL.

Although platform trials have many benefits, the complexity of these designs may result not only in increased methodological but also regulatory and ethical challenges. These aspects were addressed as part of the IMI project EU Patient-Centric Clinical Trial Platforms (EU-PEARL). We reviewed the available guidelines on platform trials in the European Union and the United States. This is supported and complemented by feedback received from regulatory interactions with the European Medicines Agency and the US Food and Drug Administration. Throughout the project we collected the needs of all relevant stakeholders including ethics committees, regulators, and health technology assessment bodies through active dialog and dedicated stakeholder workshops. Furthermore, we focused on methodological aspects and where applicable identified the corresponding guidance. Learnings from the guideline review, regulatory interactions, and workshops are provided. Based on these, a master protocol template was developed. Issues that still need harmonization or clarification in guidelines or where further methodological research is needed are also presented. These include questions around clinical trial submissions in Europe, the need for multiplicity control across the whole master protocol, the use of non-concurrent controls, and the impact of different randomization schemes. Master protocols are an efficient and patient-centered clinical trial design that can expedite drug development. However, they can also introduce additional operational and regulatory complexities. It is important to understand the different requirements of stakeholders upfront and address them in the trial. While relevant guidance is increasing, early dialog with relevant stakeholders can help to further support such designs.

Adaptive platform trials: the impact of common controls on type one error and power.

Platform trials offer a framework to study multiple interventions in one trial with the opportunity of opening and closing arms. The use of common controls can increase efficiency as compared to individual controls. The need for multiplicity adjustment because of common controls is currently a debate among researchers, pharmaceutical companies, and regulators. The impact of common controls on the type one error in a fixed platform trial, i.e. when all treatments start and end recruitment at the same time, has been discussed in the literature before. We complement these findings by investigating the impact of a common control on the type one error and power in a flexible platform trial, i.e. when one arm joins the platform later. We derived the correlation of test statistics to assess the impact of the overlap and compared the results to a trial with individual controls. Furthermore, we evaluate the power, and the impact of multiplicity adjustment on the power in fixed and flexible platform trials. These methodological considerations are complemented by a regulatory guideline review. With multiple arms, the FWER is inflated when no multiplicity adjustment is applied. However, the FWER inflation is smaller with common controls than with individual controls. Even after multiplicity adjustment, a trial with common controls is often beneficial in terms of sample size and power. However, in some cases, the trial with common controls loses the efficiency gain and it might be advisable to run a separate trial rather than joining a platform trial.

On the use of non-concurrent controls in platform trials: a scoping review.

BACKGROUND: Platform trials gained popularity during the last few years as they increase flexibility compared to multi-arm trials by allowing new experimental arms entering when the trial already started. Using a shared control group in platform trials increases the trial efficiency compared to separate trials. Because of the later entry of some of the experimental treatment arms, the shared control group includes concurrent and non-concurrent control data. For a given experimental arm, non-concurrent controls refer to patients allocated to the control arm before the arm enters the trial, while concurrent controls refer to control patients that are randomised concurrently to the experimental arm. Using non-concurrent controls can result in bias in the estimate in case of time trends if the appropriate methodology is not used and the assumptions are not met. METHODS: We conducted two reviews on the use of non-concurrent controls in platform trials: one on statistical methodology and one on regulatory guidance. We broadened our searches to the use of external and historical control data. We conducted our review on the statistical methodology in 43 articles identified through a systematic search in PubMed and performed a review on regulatory guidance on the use of non-concurrent controls in 37 guidelines published on the EMA and FDA websites. RESULTS: Only 7/43 of the methodological articles and 4/37 guidelines focused on platform trials. With respect to the statistical methodology, in 28/43 articles, a Bayesian approach was used to incorporate external/non-concurrent controls while 7/43 used a frequentist approach and 8/43 considered both. The majority of the articles considered a method that downweights the non-concurrent control in favour of concurrent control data (34/43), using for instance meta-analytic or propensity score approaches, and 11/43 considered a modelling-based approach, using regression models to incorporate non-concurrent control data. In regulatory guidelines, the use of non-concurrent control data was considered critical but was deemed acceptable for rare diseases in 12/37 guidelines or was accepted in specific indications (12/37). Non-comparability (30/37) and bias (16/37) were raised most often as the general concerns with non-concurrent controls. Indication specific guidelines were found to be most instructive. CONCLUSIONS: Statistical methods for incorporating non-concurrent controls are available in the literature, either by means of methods originally proposed for the incorporation of external controls or non-concurrent controls in platform trials. Methods mainly differ with respect to how the concurrent and non-concurrent data are combined and temporary changes handled. Regulatory guidance for non-concurrent controls in platform trials are currently still limited.

On model-based time trend adjustments in platform trials with non-concurrent controls.

BACKGROUND: Platform trials can evaluate the efficacy of several experimental treatments compared to a control. The number of experimental treatments is not fixed, as arms may be added or removed as the trial progresses. Platform trials are more efficient than independent parallel group trials because of using shared control groups. However, for a treatment entering the trial at a later time point, the control group is divided into concurrent controls, consisting of patients randomised to control when that treatment arm is in the platform, and non-concurrent controls, patients randomised before. Using non-concurrent controls in addition to concurrent controls can improve the trial's efficiency by increasing power and reducing the required sample size, but can introduce bias due to time trends. METHODS: We focus on a platform trial with two treatment arms and a common control arm. Assuming that the second treatment arm is added at a later time, we assess the robustness of recently proposed model-based approaches to adjust for time trends when utilizing non-concurrent controls. In particular, we consider approaches where time trends are modeled either as linear in time or as a step function, with steps at time points where treatments enter or leave the platform trial. For trials with continuous or binary outcomes, we investigate the type 1 error rate and power of testing the efficacy of the newly added arm, as well as the bias and root mean squared error of treatment effect estimates under a range of scenarios. In addition to scenarios where time trends are equal across arms, we investigate settings with different time trends or time trends that are not additive in the scale of the model. RESULTS: A step function model, fitted on data from all treatment arms, gives increased power while controlling the type 1 error, as long as the time trends are equal for the different arms and additive on the model scale. This holds even if the shape of the time trend deviates from a step function when patients are allocated to arms by block randomisation. However, if time trends differ between arms or are not additive to treatment effects in the scale of the model, the type 1 error rate may be inflated. CONCLUSIONS: The efficiency gained by using step function models to incorporate non-concurrent controls can outweigh potential risks of biases, especially in settings with small sample sizes. Such biases may arise if the model assumptions of equality and additivity of time trends are not satisfied. However, the specifics of the trial, scientific plausibility of different time trends, and robustness of results should be carefully considered.

Radiotherapeutic management of cervical lymph node metastases from an unknown primary site - experiences from a large cohort treated with modern radiation techniques.

PURPOSE: To analyze management and outcomes following (chemo)radiation therapy in patients with cervical lymph node metastases from an unknown primary site (CCUP) in a large single-center cohort. METHODS: Between 2008 and 2019, 58 patients with CCUP were treated with (chemo)radiation therapy at the University of Freiburg Medical Center and were included in this analysis. Overall survival (OS), locoregional progression-free survival (PFS) and distant metastasis-free survival (DMFS) were calculated using the Kaplan-Meier method. The use of diagnostic procedures and their impact on oncological outcomes was analyzed by Cox regression, and treatment-related toxicities were quantified. RESULTS: Median follow-up was 29.9 months (range 4.6-121.9). Twenty-one patients (36.2%) received definitive RT, 35 (60.3%) underwent adjuvant RT, and 2 (3.4%) were treated for oligometastatic disease. Concurrent chemotherapy was prescribed in 40 patients (69.0%). 89.6% of patients completed the prescribed RT, and 65.0% completed the prescribed simultaneous chemotherapy. Locoregional recurrence was observed in 7 patients (12.1%) and distant metastases in 13 cases (22.4%). OS was 81,1, 64.9% and 56,6% after 1, 3 and 5 years, respectively. Univariate analysis of age, gender, extracapsular spread, tumor grading, neck dissection, diagnostic utilization of 18F-fluorodeoxyglucose positron-emission tomography and concomitant chemotherapy showed no effect on OS (p > 0.05 for all), while smoking was significantly associated with decreased survival (p < 0.05). There was a trend towards impaired OS for patients with advanced nodal status (pN3) (p = 0.07). Three patients (5.2%) experienced grade 3 radiation dermatitis, and 12 (22.4%) developed grade 3 and 1 (1.7%) grade 4 mucositis. CONCLUSIONS: RT of the panpharynx and cervical lymph nodes with concurrent chemotherapy in case of risk factors demonstrated good locoregional control, but the metachronous occurrence of distant metastases limited survival and must be further addressed.

Prevalence and relevance of impaired left ventricular function in chronic moderate regurgitation of native aortic valves.

Background: Reduced ejection fraction (EF) in chronic moderate aortic regurgitation (AR) could be either due to a late remodelling response after longstanding moderate AR, or could represent a specific phenotype of cardiomyopathy (CMP) with concomitant AR. The aim of this study was to analyse progression of left ventricular (LV) impairment in moderate AR.Methods: All patients in our echocardiography database between 2005 and 2016 were screened to identify pure chronic moderate AR, excluding significant coronary artery disease (CAD) or concomitant valve disease. Remaining 152 patients were divided into three groups: (a) preserved systolic LV function; (b) reduced LV EF and prediagnosed concomitant cardiomyopathy (CMP); (c) reduced LV EF without prediagnosed CMP.Results: The majority patients (group A = 66%) had preserved systolic LV function, remaining oligosymptomatic with stable LVEDD at follow-up. Non-CMP patients with reduced EF at baseline (group C = 18%) were significantly older (group C: 74 vs. group A: 61 years, p < .001) whereas left ventricular end-diastolic diameter (LVEDD) significantly increased over time (p = .046). Development of renal insufficiency, atrial fibrillation and NYHA > II were significant risk factors linked to the worsening of LV function in patients with moderate AR.Conclusion: Preserved LV EF and LVEDD remain stable over a long lasting period in the majority of patients. However, these data suggest that some patients develop reduced LV EF, even without progression of AR to severe, especially if renal insufficiency or atrial fibrillation are present.

Bone density and pain response following intensity-modulated radiotherapy versus three-dimensional conformal radiotherapy for vertebral metastases - secondary results of a randomized trial.

BACKGROUND: This was a prespecified secondary analysis of a randomized trial that analyzed bone density and pain response following fractionated intensity-modulated radiotherapy (IMRT) versus three-dimensional conformal radiotherapy (3DCRT) for palliative management of spinal metastases. METHODS/MATERIALS: Sixty patients were enrolled in the single-institutional randomized exploratory trial, randomly assigned to receive IMRT or 3DCRT (30 Gy in 10 fractions). Along with pain response (measured by the Visual Analog Scale (VAS) and Chow criteria), quantitative bone density was evaluated at baseline, 3, and 6 months in both irradiated and unirradiated spinal bodies, along with rates of pathologic fractures and vertebral compression fractures. RESULTS: Relative to baseline, bone density increased at 3 and 6 months following IMRT by a median of 24.8% and 33.8%, respectively (p < 0.01 and p = 0.048). These figures in the 3DCRT cohort were 18.5% and 48.4%, respectively (p < 0.01 for both). There were no statistical differences in bone density between IMRT and 3DCRT at 3 (p = 0.723) or 6 months (p = 0.341). Subgroup analysis of osteolytic and osteoblastic metastases showed no differences between groups; however, mixed metastases showed an increase in bone density over baseline in the IMRT (but not 3DCRT) arm. The 3-month rate of the pathological fractures was 15.0% in the IMRT arm vs. 10.5% in the 3DCRT arm. There were no differences in pathological fractures at 3 (p = 0.676) and 6 (p = 1.000) months. The IMRT arm showed improved VAS scores at 3 (p = 0.037) but not 6 months (p = 0.430). Using Chow criteria, pain response was similar at both 3 (p = 0.395) and 6 (p = 0.732) months. CONCLUSIONS: This the first prospective investigation evaluating the impact of IMRT vs. 3DCRT on bone density. Along with pain response and pathologic fracture rates, significant rises in bone density after 3 and 6 months were similar in both cohorts. Future randomized investigations with larger sample sizes are recommended. TRIAL REGISTRATION: NCT, NCT02832830 . Registered 14 July 2016.

Local response and pathologic fractures following stereotactic body radiotherapy versus three-dimensional conformal radiotherapy for spinal metastases - a randomized controlled trial.

BACKGROUND: This was a prespecified secondary analysis of a randomized trial, which analyzed bone density following stereotactic body radiotherapy (SBRT) versus conventional three-dimensional conformal radiotherapy (3DCRT) as part of palliative management of painful spinal metastases. METHODS: Fifty-five patients were enrolled in this single-institutional randomized exploratory trial (NCT02358720). Participants were randomly assigned to receive SBRT (single-fraction 24 Gy) or 3DCRT (30 Gy/10 fractions). Quantitative bone density was evaluated at baseline, 3 and 6 months in both irradiated and unirradiated spinal bodies, along with rates of pathologic fractures and vertebral compression fractures. RESULTS: As compared to baseline, bone density became significantly higher at 3 and 6 months following SBRT by a median of 33.8% and 72.1%, respectively (p < 0.01 for both). These figures in the 3DCRT cohort were 32.9% and 41.2%, respectively (p < 0.01 for both). There were no statistical differences in bone density between SBRT and 3DCRT at 3 (p = 0.629) or 6 months (p = 0.327). Subgroup analysis of osteolytic metastases showed an increase in bone density relative to baseline in the SBRT (but not 3DCRT) arm. Bone density in unaffected vertebrae did not show substantial changes in either group. The 3-month incidence of new pathological fractures was 8.7% in the SBRT arm vs. 4.3% in the 3DCRT arm. CONCLUSIONS: Despite high ablative doses in the SBRT arm, the significant increase in bone density after 3 and 6 months was similar to that of 3DCRT. Our trial demonstrated a moderate rate of subsequent pathological fracture after SBRT. Future randomized investigations with larger sample sizes are recommended. TRIAL REGISTRATION: www.clinicaltrials.gov : NCT02358720 on 9nd of February 2015.

Cost-Effectiveness of Carbon Ion Radiation Therapy for Skull Base Chordoma Utilizing Long-Term (10-Year) Outcome Data.

BACKGROUND/AIM: Carbon ion radiotherapy (CIRT) offers high conformality and ability to dose-escalate skull base chordomas, with promising clinical data. However, it is an imperative measure to economically justify the use of such high-priced new technologies. Herein, we investigated the cost-effectiveness of CIRT compared to photon radiotherapy (PRT) using 10-year outcome data extrapolated to a 34-year time frame. MATERIALS AND METHODS: Data regarding costs of PRT, as well as 10-year outcomes were obtained from published sources. Corresponding figures for CIRT were acquired from institutional and published sources. Adjustment was made in order to compare both cost figures, including elimination of additional financing and follow-up, so that only direct costs of treatment and the cost of progression were compared between both modalities. The incremental cost-effectiveness ratio (ICER) was calculated as the difference in cost between both modalities divided by the difference in 34-year quality-adjusted life-year (QALY) outcomes. The annual gross domestic product per capita cost-effectiveness threshold definition (as recommended by the WHO) was employed. RESULTS: The total cost of a complete course of CIRT (20-22 fractions) was €31,538.21. After removal of financing and follow-up costs, the adjusted direct cost of CIRT utilized for comparison was €18,957.78. In a previous publication, the cost of PRT was €4,700.00. ICERs were based upon these direct cost figures and the average of reported 10-year progression-free survival (PFS) values with PRT (41.1%) and CIRT (54%), as well as gained PFS years (10.66 years CIRT, 8.58 years PRT). QALYs were 6.65 for photon RT and 8.26 for CIRT, a difference of 1.61 discounted lifetime QALYs for patients treated with CIRT. The overall ICER was €8,855.76/QALY. If the cost of progression/recurrence treated with imatinib were included into the calculation, the total ICER was €170.61/QALY. CONCLUSION: CIRT is a highly cost-effective option to treat chordoma.

Quality of Life and Radiation-induced Late Toxicity Following Intensity-modulated Versus Three-dimensional Conformal Radiotherapy for Patients with Spinal Bone Metastases: Results of a Randomized Trial.

BACKGROUND/AIM: Quality of life (QOL) is becoming increasingly important to appraise the value of a particular oncologic intervention. This was a prespecified secondary analysis of a randomized trial (NCT02832830) of intensity-modulated radiotherapy (IMRT) versus conventional three-dimensional conformal radiotherapy (3DCRT) as part of palliative management of symptomatic spinal metastases. This study examined QOL, fatigue, emotional distress, and late toxicities between patients having received IMRT versus 3DCRT. MATERIALS AND METHODS: Sixty patients were enrolled in this single-institutional randomized exploratory trial in which all patients received 30 Gy in 10 fractions. The EORTC QLQ-BM22, EORTC QLQ-FA13, and QSC-R10 questionnaires were utilized to evaluate QOL, fatigue, and emotional distress, respectively; endpoints were evaluated at baseline, and at 3, and 6 months. Late (6 months) toxicities were assessed according to the LENT-SOMA criteria. RESULTS: Mean follow-up was 192 days (IQR=77-285). Although QOL was similar between groups, patients in the IMRT arm experienced lower physical (p=0.011) and emotional (p=0.017) fatigue at 6 months. Emotional distress was also lower in IMRT-treated patients after six months (p=0.039). Cohen's effect size confirmed the clinically significant improvement of these findings. Late toxicities occurred infrequently and were similar between arms. CONCLUSION: This is the first randomized study evaluating QOL between IMRT and 3DCRT to palliate vertebral metastases. IMRT resulted in reduced physical and emotional fatigue as well as emotional distress. IMRT should be further studied for these patients given these outcomes.

Survival and Stability of Patients with Urothelial Cancer and Spinal Bone Metastases after Palliative Radiotherapy.

BACKGROUND: The aim of the study was to analyze survival and stability of patients with urothelial cell cancer and spinal bone metastases (SBM) after radiotherapy (RT). Furthermore, to assess the effects of RT on bone mineral density (BMD) as a local response in SBM after RT. PATIENTS AND METHODS: Survival of 38 patients with 132 SBM from urothelial cancer, treated from January 2000 to January 2012, was calculated. Stability of irradiated thoracic and lumbar SBM was retrospectively evaluated in computed tomography (CT) scans using the validated Taneichi et al. score. Difference in BMD, measured in Hounsfield units (HU), of the SBM before and at 3 and 6 months after RT was analyzed. RESULTS: All patients died during follow-up. Overall survival (OS) after 6 months, 1 year and 2 years was 90%, 80% and 40%, respectively. Bone survival (BS) was 85%, 64% and 23% after 6 months, 1 year and 2 years, respectively. Survival from start of RT (RTS) was 42% after 6 months, 18% after 1 year and 5% after 2 years. Only 11% received bisphosphonates. Stability did not improve at 3 or 6 months after RT. BMD increased by 25.0 HU ± 49.7 SD after 3 months (p = 0.001) and by 24.2 HU ± 52.2 SD after 6 months (p = 0.037). Pain relief (> 2 points on the visual analogue scale) was achieved in only 27% of patients. CONCLUSIONS: Benefit from palliative RT of painful or unstable SBM is limited in these patients and they should be carefully selected for RT. Shorter fractionation schedules may be preferred and outcome may improve with concomitant bisphosphonates.

The influence of fractionated radiotherapy on the stability of spinal bone metastases: a retrospective analysis from 1047 cases.

BACKGROUND: The effect of radiotherapy, in particular the application of different multi-fraction schedules in the management of unstable spinal bone metastases (SBM), is incompletely understood. This study aims to compare the radiological response regarding various dose and fractionation schedules of radiotherapy in the palliative treatment of SBM. METHODS: We retrospectively assessed 1047 patients with osteolytic SBM, treated with palliative radiotherapy at our department between 2000 and 2015. Lung cancer (40.2%), breast (16.7%) and renal cancer (15.2%) were the most common solid tumors in this study. Different common multi-fraction regimen (5x4Gy, 10x3Gy, 14 × 2.5Gy and 20x2Gy) were compared with regard to radiological response and recalcification at 3 and 6 months after radiotherapy. The Taneichi score was used for classification of osteolytic SBM. RESULTS: Median follow up was 6.3 months. The median overall survival (OS) in the short-course radiotherapy (SCR) group using less than 10 treatment fractions was 5.5 months vs. 9.5 months in the long-course radiotherapy (LCR) group using in excess of 10 fractions (log rank p < .0001). Overall survival (OS) in the SCR group after 3 and 6 months was 66.8 and 49.1%, respectively vs 80.9 and 61.5%, respectively in the LCR group. 17.6% (n = 54/306) and 31.1% (n = 89/286) of unstable SBM were classified as stable in the SCR group at 3 and 6 months post radiotherapy, respectively (p < .001 for both). In the LCR group, 24.1% (n = 28/116) and 34.2% (n = 38/111) of unstable SBM were stabilized after 3 and 6 months, respectively (p < .001 for both). CONCLUSIONS: Our study shows no significant difference in stabilization achieving recalcification rates between multi-fraction schedules (SCR vs. LCR) in the palliative management of unstable SBM. Both groups with multi-fraction regimen demonstrate a stabilizing effect following 3 and 6 months after radiotherapy.

Bright light therapy versus physical exercise to prevent co-morbid depression and obesity in adolescents and young adults with attention-deficit / hyperactivity disorder: study protocol for a randomized controlled trial.

BACKGROUND: The risk for major depression and obesity is increased in adolescents and adults with attention-deficit / hyperactivity disorder (ADHD) and adolescent ADHD predicts adult depression and obesity. Non-pharmacological interventions to treat and prevent these co-morbidities are urgently needed. Bright light therapy (BLT) improves day-night rhythm and is an emerging therapy for major depression. Exercise intervention (EI) reduces obesity and improves depressive symptoms. To date, no randomized controlled trial (RCT) has been performed to establish feasibility and efficacy of these interventions targeting the prevention of co-morbid depression and obesity in ADHD. We hypothesize that the two manualized interventions in combination with mobile health-based monitoring and reinforcement will result in less depressive symptoms and obesity compared to treatment as usual in adolescents and young adults with ADHD. METHODS: This trial is a prospective, pilot phase-IIa, parallel-group RCT with three arms (two add-on treatment groups [BLT, EI] and one treatment as usual [TAU] control group). The primary outcome variable is change in the Inventory of Depressive Symptomatology total score (observer-blinded assessment) between baseline and ten weeks of intervention. This variable is analyzed with a mixed model for repeated measures approach investigating the treatment effect with respect to all three groups. A total of 330 participants with ADHD, aged 14 - < 30 years, will be screened at the four study centers. To establish effect sizes, the sample size was planned at the liberal significance level of α = 0.10 (two-sided) and the power of 1-ß = 80% in order to find medium effects. Secondary outcomes measures including change in obesity, ADHD symptoms, general psychopathology, health-related quality of life, neurocognitive function, chronotype, and physical fitness are explored after the end of the intervention and at the 12-week follow-up. DISCUSSION: This is the first pilot RCT on the use of BLT and EI in combination with mobile health-based monitoring and reinforcement targeting the prevention of co-morbid depression and obesity in adolescents and young adults with ADHD. If at least medium effects can be established with regard to the prevention of depressive symptoms and obesity, a larger scale confirmatory phase-III trial may be warranted. TRIAL REGISTRATION: German Clinical Trials Register, DRKS00011666. Registered on 9 February 2017. ClinicalTrials.gov, NCT03371810. Registered on 13 December 2017.

Sustainable reduction of antibiotic-induced antimicrobial resistance (ARena) in German ambulatory care: study protocol of a cluster randomised trial.

BACKGROUND: Despite many initiatives to enhance the rational use of antibiotics, there remains substantial room for improvement. The overall aim of this study is to optimise the appropriate use of antibiotics in German ambulatory care in patients with acute non-complicated infections (respiratory tract infections, such as bronchitis, sinusitis, tonsillitis and otitis media), community-acquired pneumonia and non-complicated cystitis, in order to counter the advancing antimicrobial resistance development. METHODS: A three-armed cluster randomised trial will be conducted in 14 practice networks in two German federal states (Bavaria and North Rhine-Westphalia) and an added cohort that reflects standard care. The trial is accompanied by a process evaluation. Each arm will receive a different set of implementation strategies. Arm A receives a standard set, comprising of e-learning on communication with patients and quality circles with data-based feedback for physicians, information campaigns for the public, patient information material and performance-based additional reimbursement. Arm B receives this standard set plus e-learning on communication with patients and quality circles with data-based feedback tailored for non-physician health professionals of the practice team and information material for tablet computers (culture sensitive). Arm C receives the standard set as well as a computerised decision support system and quality circles in local multidisciplinary groups. The study aims to recruit 193 practices which will provide data on 23,934 patients each year (47,867 patients in total). The outcome evaluation is based on claims data and refers to established indicators of the European Surveillance of Antimicrobial Consumption Network (ESAC-Net). Primary and secondary outcomes relate to prescribing of antibiotics, which will be analysed in multivariate regression models. The process evaluation is based on interviews with surveys among physicians, non-physician health professionals of the practice team and stakeholders. A patient survey is conducted in one of the study arms. Interview data will be qualitatively analysed using thematic framework analysis. Survey data of physicians, non-physician health professionals of the practice team and patients will use descriptive and exploratory statistics for analysis. DISCUSSION: The ARena trial will examine the effectiveness of large scale implementation strategies and explore their delivery in routine practice. TRIAL REGISTRATION: ISRCTN, ISRCTN58150046 . Registered 24 August 2017.

Blinded sample size recalculation in clinical trials incorporating historical data.

Recruiting sufficient patients within an acceptable time horizon is an issue for most clinical trials and is especially challenging in the field of rare diseases. It is therefore an attractive option to include historical data from previous (pilot) trials in the current study thus reducing the recruitment burden. In clinical trials with binary endpoint, the required sample size does not only depend on the type I error rate, the power, and the treatment group difference but additionally on the overall event rate. However, there is usually some uncertainty in the planning phase about the value of this nuisance parameter. We present methods for blinded sample size recalculation in the setting of two-arm superiority trials with historical control data where the overall rate is estimated mid-course and the sample size is recalculated accordingly. The operating characteristics of the method are investigated in terms of actual type I error rate, power, and expected sample size. Application is illustrated with a clinical trial example in patients with systemic sclerosis, a rare connective tissue disorder.

Long-Term Outcome of Steroid-Resistant Nephrotic Syndrome in Children.

We investigated the value of genetic, histopathologic, and early treatment response information in prognosing long-term renal outcome in children with primary steroid-resistant nephrotic syndrome. From the PodoNet Registry, we obtained longitudinal clinical information for 1354 patients (disease onset at >3 months and <20 years of age): 612 had documented responsiveness to intensified immunosuppression (IIS), 1155 had kidney biopsy results, and 212 had an established genetic diagnosis. We assessed risk factors for ESRD using multivariate Cox regression models. Complete and partial remission of proteinuria within 12 months of disease onset occurred in 24.5% and 16.5% of children, respectively, with the highest remission rates achieved with calcineurin inhibitor-based protocols. Ten-year ESRD-free survival rates were 43%, 94%, and 72% in children with IIS resistance, complete remission, and partial remission, respectively; 27% in children with a genetic diagnosis; and 79% and 52% in children with histopathologic findings of minimal change glomerulopathy and FSGS, respectively. Five-year ESRD-free survival rate was 21% for diffuse mesangial sclerosis. IIS responsiveness, presence of a genetic diagnosis, and FSGS or diffuse mesangial sclerosis on initial biopsy as well as age, serum albumin concentration, and CKD stage at onset affected ESRD risk. Our findings suggest that responsiveness to initial IIS and detection of a hereditary podocytopathy are prognostic indicators of favorable and poor long-term outcome, respectively, in children with steroid-resistant nephrotic syndrome. Children with multidrug-resistant sporadic disease show better renal survival than those with genetic disease. Furthermore, histopathologic findings may retain prognostic relevance when a genetic diagnosis is established.