A guide to the design and analysis of small clinical studies

Oxidation‑reduction potential parameters worsen following intraarterial therapy in patients with reduced collateral circulation and middle cerebral artery occlusions

Collateral circulation is important for cerebral perfusion in acute ischemic strokes. Monitoring the oxidation-reduction potential (ORP) may be useful to assess collateral status or treatment efficacy. The objectives of the present study were to determine if the ORP was associated with collateral circulation status in middle cerebral artery (MCA) occlusions and to identify patterns in the ORP and the collateral circulation status among patients treated with intraarterial therapy (IAT) over time. The present pilot study was nested within a prospective cohort study measuring the ORP of the peripheral venous plasma of stroke patients. The population included in the present study were patients with MCA (M1/M2) occlusions. Two ORP parameters were examined: Static ORP (sORP; mV), indicating oxidative stress, and capacity ORP (cORP; µC), indicating antioxidant reserves. Collateral status was retrospectively graded using Miteff's system as good (grade 1) or reduced (grade 2/3). Comparisons were made between collateral status groups (reduced vs. good collaterals) in all patients, within a subset including only patients who received IAT, and between thrombolysis in cerebral infraction scale score (TICI) groups (0-2a vs. 2b/3). The Fisher's exact test, Student's t-test and Wilcoxon tests were used (α<0.20). The 19 patients were categorized based on their collaterals: Good collaterals (53%) and reduced collaterals (47%). The baseline characteristics were similar with the exception that the patients with good collaterals had a lower international normalized ratio (P=0.12) and were more likely to have a stroke on the left side (P=0.18) or to have a mismatch (P=0.05). The admission sORP values were comparable (169.5 vs. 164.2 mV; P=0.65), as was admission cORP (P=0.73). When considering only the patients who received IAT (n=12), admission sORP (P=0.69) and cORP (P=0.90) were also statistically similar. On day 2, after IAT, both groups experienced a worsening in ORP measures; however, the patients with good collaterals had a significantly lower sORP (169.4 vs. 203.5 mV; P=0.02) and a higher cORP (0.2 vs. 0.1 µC; P=0.002) compared with the patients with reduced collaterals. Neither sORP nor cORP were significantly different between TICI score groups on admission or on day 2. Upon discharge, patients with a TICI of 2b-3 had a significantly better sORP (P=0.03) and cORP (P=0.12) compared with those with a TICI of 0-2a. In conclusion, upon patient admission, the ORP parameters were not significantly different between the collateral circulation status groups for MCA occlusions. The ORP parameters worsened after IAT regardless of the collateral circulation status; however, after IAT, on day 2, patients with good collaterals experienced less oxidative stress (sORP) and had higher antioxidant reserves (cORP) than patients with reduced collaterals.

Psoriasis improvements and inflammatory biomarker normalization with secukinumab: the randomized ObePso-S study

BACKGROUND

The IL-17A inhibitor secukinumab has demonstrated consistent efficacy and safety in patients with moderate-to-severe plaque psoriasis, with normalization of molecular and histopathologic psoriasis markers.

OBJECTIVE

To investigate treatment effects of secukinumab on clinical signs and psoriatic inflammation markers over 52 weeks in patients with psoriasis.

METHODS

In the ObePso-S study (NCT03055494), patients with psoriasis were randomized 2:1 to receive secukinumab 300 mg (n = 54) or placebo (n = 28), stratified by body weight (<90 or ≥90 kg), for 52 weeks. At Week 12, patients receiving placebo were switched to secukinumab. Psoriasis Area and Severity Index improvement of 90% (PASI90) and Investigator's Global Assessment modified 2011 0/1 responses were assessed at Weeks 12 and 52. Immunohistochemistry for keratin 16 (K16) and gene expression profiles were evaluated in lesional and non-lesional skin biopsies collected at baseline, Week 12, and Week 52.

RESULTS

Of patients receiving secukinumab, 55.8% and 59.6% achieved PASI90 at Weeks 12 and 52, respectively. K16 was absent in 93.1% of Week 12 PASI90 responders and 93.6% of Week 52 PASI90 responders, which mirrored the down-regulated expression of psoriatic inflammation. Week 52 PASI90 non-responders experienced regression of clinical and inflammatory marker responses toward baseline levels. Lower control of inflammatory gene expression at Week 12 was associated with suboptimal clinical responses at Week 52.

CONCLUSION

Sustained clinical responses with secukinumab were associated with rapid and sustained normalization of K16 and inflammatory gene expression in most patients. Molecular anti-inflammatory effects of secukinumab at Week 12 were associated with clinical responses at Week 52.

Changes in frontal plane kinematics over 12-months in individuals with the Percutaneous Osseointegrated Prosthesis (POP)

BACKGROUND

A bone-anchored prosthesis (BAP) eliminates the need for a conventional socket by attaching a prosthesis directly to the user's skeleton. Currently, limited research addresses changes in gait mechanics post BAP implantation.

OBJECTIVE

Examine changes in frontal plane movement patterns after BAP implantation.

METHODS

Participants were individuals with unilateral transfemoral amputation (TFA) enrolled in the US Food and Drug Administration (FDA) Early Feasibility Study examining the Percutaneous Osseointegrated Prosthesis (POP). The participants completed overground gait assessments using their conventional socket and at 6-weeks, 12-weeks, 6-months, and 12-months following POP implantation. Statistical parameter mapping techniques were used in examining changes in frontal plane kinematics over the 12-months and differences with reference values for individuals without limb loss.

RESULTS

Statistically significant deviations were found pre-implantation compared to reference values for hip and trunk angles during prosthetic limb stance phase, and for pelvis and trunk relative to the pelvis angles during prosthetic limb swing. At 6-weeks post-implantation, only the trunk angle demonstrated a statistically significant reduction in the percent of gait cycle with deviations relative to reference values. At 12-months post-implantation, results revealed frontal plane movements were no longer statistically different across the gait cycle for the trunk angle compared to reference values, and less of the gait cycle was statistically different compared to reference values for all other frontal plane patterns analyzed. No statistically significant within-participant differences were found for frontal plane movement patterns between pre-implantation and 6-weeks or 12-months post-implantation.

CONCLUSIONS

Deviations from reference values displayed prior to device implantation were reduced or eliminated 12-months post-implantation in all frontal plane patterns analyzed, while within-participant changes over the 12-month period did not reach statistical significance. Overall, the results suggest the transition to a BAP aided in normalizing gait patterns in a sample of relatively high functioning individuals with TFA.

Chronic Migraine Preventive Treatment by Prefrontal-Occipital Transcranial Direct Current Stimulation (tDCS): A Proof-of-Concept Study on the Effect of Psychiatric Comorbidities

Chronic migraine (CM) is often complicated by medication overuse headache (MOH) and psychiatric comorbidities that may influence the clinical outcome. This study aimed to investigate the relationship between psychiatric comorbidities and the effect of transcranial direct current stimulation (tDCS) in patients with CM with or without MOH. We recruited 16 consecutive CM patients who had an unsatisfactory response to at least three pharmacological preventive therapies. They were treated with anodal right-prefrontal and cathodal occipital tDCS (intensity: 2 mA, time: 20 min) three times per week for 4 weeks. All patients underwent a psychopathological assessment before and after treatment, and five of them were diagnosed with bipolar disorder (BD). After treatment, all the patients showed a significant decrease of severe and overall headache days per month. Despite having a higher migraine burden at baseline, patients with CM and BD showed a significantly greater reduction of severe headaches and psychiatric symptoms. Overall, tDCS seems to be effective in the treatment of CM patients with a poor response to different classes of pharmacological therapies, whereas BD status positively influences the response of migraineurs to tDCS.

Sweat and saliva cortisol response to stress and nutrition factors

Cortisol is a biomarker for stress monitoring; however, the biomedical and clinical relevance is still controversial due to the complexity of cortisol secretion mechanisms and their circadian cycles as well as environmental factors that affect physiological cortisol level, which include individual mood and dietary intake. To further investigate this multifaceted relationship, a human pilot study examined cortisol concentration in sweat and saliva samples collected from 48 college-aged participants during aerobic exercise sessions along with mental distress and nutrition surveys. Enzyme-linked immunosorbent assays determined highly significant differences between apocrine-dominant sweat (AP), saliva before exercise (SBE), and saliva after exercise (SAE) cortisol concentration (AP-SBE: p = 0.0017, AP-SAE: p = 0.0102). A significantly greater AP cortisol concentration was detected in males compared to females (p = 0.0559), and significant SAE cortisol concentration differences were also recorded between recreational athletes and non-athletes (p = 0.044). However, Kessler 10 Psychological Distress Scale (K10) scores, an examination administered to deduce overall wellness, provided no significant differences between males and females or athletes and non-athletes in distress levels, which statistically signifies a direct relationship to cortisol was not present. For further analysis, dietary intake from all participants was considered to investigate whether a multiplexed association was prevalent between nutrition, mood, and cortisol release. Significant positive correlations between AP cortisol, SAE cortisol, K10 scores, and fat intake among female participants and athletes were discovered. The various machine learning algorithms utilized the extensive connections between dietary intake, overall well-being, sex factors, athletic activity, and cortisol concentrations in various biofluids to predict K10 scores. Indeed, the understanding of physiochemical stress response and the associations between studied factors can advance algorithm developments for cortisol biosensing systems to mitigate stress-based illnesses and improve an individual's quality of life.

Generate-Boost: study protocol for a prospective, multicenter, randomized controlled, double-blinded phase II trial to evaluate efficacy and safety of bortezomib in patients with severe autoimmune encephalitis

BACKGROUND

Autoimmune encephalitis is a new spectrum of autoimmune disorders of the central nervous system (CNS), which are characterized by pathogenic autoantibodies against neuronal surface antigens. Clinical presentations range from acute to subacute encephalopathy with neurological and psychiatric symptoms, and life-threatening autonomic dysfunction in severe cases. There exist no approved therapies nor is data available from controlled clinical trials. Patients are usually treated with diverse combinations of immunotherapy. However, effect of immunotherapy on antibody-producing cells and thus on levels of pathogenic autoantibodies is insufficient. Therefore, therapeutic response is sometimes prolonged with necessity of long-time intensive care treatment and also irreversible deficits occur in severe cases. This trial will investigate the efficacy and safety of bortezomib, a proteasome inhibitor known to selectively deplete plasma cells, in patients with severe autoimmune encephalitis who have been treated with rituximab with insufficient response.

METHODS

Generate-Boost is an investigator-initiated, multicenter, double-blinded, randomized controlled phase II trial which will be conducted in specialized neurological hospitals within the GENERATE (GErman NEtwork for Research on AuToimmune Encephalitis) network in Germany. Adult patients with severe autoimmune encephalitis (modified Rankin scale, mRS ≥ 3), autoantibodies against neuronal surface antigens, and pretreatment with rituximab are eligible for study participation. Fifty patients will be randomized 1:1 and undergo up to 3 cycles (each 21 days with 4 s. c. applications) of bortezomib or placebo. All patients will receive concomitant medication with dexamethasone, acyclovir and co-trimoxazole. The primary efficacy endpoint is the mRS score 17 weeks after first treatment application. Secondary endpoints are neurocognitive function, antibody titers, markers of neuronal cell damage, length of ICU/hospital stay, and mRS and Glasgow coma scale scores throughout the trial up to week 17. General and bortezomib-specific adverse events are monitored continuously.

DISCUSSION

The expected outcome of the study is to obtain first reliable data on a hypothesis-driven therapeutic option in severe and difficult-to-treat autoimmune encephalitis. If treatment with bortezomib is beneficial in these cases, this will be the basis for implementation in the current guidelines.

TRIAL REGISTRATION

Clinicaltrials.gov , NCT03993262 . Registered June 20, 2019; German Clinical Trials Register, DRKS00017497.

Associations between non-anaemic iron deficiency and outcomes following surgery for colorectal cancer: An exploratory study of outcomes relevant to prospective observational studies

Iron deficiency is common in colorectal cancer. Despite perioperative guidelines advocating for the correction of non-anaemic iron deficiency prior to major surgery, the impact of this pathology on postoperative outcome is unclear.

We conducted a single-centre, historical cohort study of 141 elective resections for colorectal cancer. We stratified non-anaemic patients into iron deficient and iron replete groups, and collected data on baseline characteristics, preoperative laboratory results, intraoperative events and postoperative outcomes. As this study was an exploratory work for future research, a P-value of 0.25 was considered relevant. Patients in the deficient group demonstrated lower baseline ferritin (median (interquartile range, IQR) 76 (41–141) µg/L versus 207 (140–334) µg/L, P < 0.001) and transferrin saturation (mean (standard deviation, SD) 18% (8%) versus 32% (12%), P < 0.001) than those in the replete group, and lower starting haemoglobin (mean (SD) 138 (10) g/L versus 144 (12) g/L, P = 0.01). The deficient group had increased re-admission (25% (24%) versus 4% (11%), P = 0.15) and all-cause infection (25% (24%) versus 5% (14%), P = 0.24). A decrease of two days in days alive and out of hospital at postoperative day 90 was seen in the deficient group on univariate analysis (median (IQR) 81 (75–84) versus 83 (78–84), P = 0.25). This reduced to 1.24 days in multivariate adjusted quantile regression analysis ( P = 0.22). Days alive and out of hospital at day 90, postoperative re-admission and postoperative infection may be meaningful outcome measures for future prospective observational work examining non-anaemic iron deficiency in patients undergoing major surgery for colorectal cancer.

Effects of Mantra Meditation versus Music Listening on Knee Pain, Function, and Related Outcomes in Older Adults with Knee Osteoarthritis: An Exploratory Randomized Clinical Trial (RCT)

OBJECTIVE

Disease-modifying treatments for OA remain elusive, and commonly used medications can have serious side effects. Although meditation and music listening (ML) have been shown to improve outcomes in certain chronic pain populations, research in OA is sparse. In this pilot RCT, we explore the effects of two mind-body practices, mantra meditation (MM) and ML, on knee pain, function, and related outcomes in adults with knee OA.

METHODS

Twenty-two older ambulatory adults diagnosed with knee OA were randomized to a MM (N=11) or ML program (N=11) and asked to practice 15-20 minutes, twice daily for 8 weeks. Core outcomes included knee pain (Knee Injury and Osteoarthritis Outcome Score [KOOS] and Numeric Rating Scale), knee function (KOOS), and perceived OA severity (Patient Global Assessment). Additional outcomes included perceived stress (Perceived Stress Scale), mood (Profile of Mood States), sleep (Pittsburgh Sleep Quality Index), and health-related quality of life (QOL, SF-36). Participants were assessed at baseline and following completion of the program.

RESULTS

Twenty participants (91%) completed the study (9 MM, 11 ML). Compliance was excellent; participants completed an average of 12.1±0.83 sessions/week. Relative to baseline, participants in both groups demonstrated improvement post-intervention in all core outcomes, including knee pain, function, and perceived OA severity, as well as improvement in mood, perceived stress, and QOL (Physical Health) (p's≤0.05). Relative to ML, the MM group showed greater improvements in overall mood and sleep (p's≤0.04), QOL-Mental Health (p<0.07), kinesiophobia (p=0.09), and two domains of the KOOS (p's<0.09).

CONCLUSIONS

Findings of this exploratory RCT suggest that a simple MM and, possibly, ML program may be effective in reducing knee pain and dysfunction, decreasing stress, and improving mood, sleep, and QOL in adults with knee OA.

Temperature-controlled laminar airflow (TLA) device in the treatment of children with severe atopic eczema: Open-label, proof-of-concept study

BACKGROUND

Children with severe, persistent atopic eczema (AE) have limited treatment options, often requiring systemic immunosuppression.

OBJECTIVE

To evaluate the effect of the temperature-controlled laminar airflow (TLA) treatment in children/adolescents with severe AE.

METHODS

We recruited 15 children aged 2-16 years with long-standing, severe AE and sensitization to ≥1 perennial inhalant allergen. Run-in period of 6-10 weeks (3 visits) was followed by 12-month treatment with overnight TLA (Airsonett^® , Sweden). The primary outcome was eczema severity (SCORAD-Index and Investigator Global Assessment-IGA). Secondary outcomes included child/family dermatology quality of life and family impact questionnaires (CDQLI, FDQLI, DFI), patient-oriented eczema measure (POEM), medication requirements and healthcare contacts. The study is registered as ISRCTN65865773.

RESULTS

There was a significant reduction in AE severity ascertained by SCORAD and IGA during the 12-month intervention period (P < .001). SCORAD was reduced from a median of 34.9 [interquartile range 28.75-45.15] at Baseline to 17.2 [12.95-32.3] at the final visit, and IGA improved significantly from 4 [3-4] to 2 [1-3]. We observed a significant improvement in FDQLI (16.0 [12.25-19.0] to 12 [8-18], P = .023) and DFI (P = .011), but not CDQLI or POEM. Compared to 6-month period prior to enrolment, there was a significant reduction at six months after the start of the intervention in potent topical corticosteroids (P = .033). The exploratory cluster analysis revealed two strongly divergent patterns of response, with 9 patients classified as responders, and 6 as non-responders.

CONCLUSION AND CLINICAL RELEVANCE

Addition of TLA device to standard pharmacological treatment may be an effective add-on to the management of difficult-to-control AE.

Randomized controlled trial of a parenting program to reduce the risk of child maltreatment in South Africa

Parenting programs in high-income countries have been shown to reduce the risk of child maltreatment. However, there is limited evidence of their effectiveness in low- and middle-income countries. The objective of this study was to examine the initial effects of a parenting program in reducing the risk of child maltreatment in highly-deprived and vulnerable communities in Cape Town, South Africa. Low-income parents (N=68) with children aged three to eight years were randomly assigned to either a group-based parenting program or a wait-list control group. Observational and parent-report assessments were taken at baseline and at immediate post-test after the intervention was delivered. Primary outcomes were parent-report and observational assessments of harsh parenting, positive parenting, and child behavior problems. Secondary outcomes were parent-report assessments of parental depression, parenting stress, and social support. Results indicated moderate treatment effects for increased frequency of parent-report of positive parenting (d=0.63) and observational assessments of parent-child play (d=0.57). Observational assessments also found moderate negative treatment effects for less frequent positive child behavior (d=-0.56). This study is the first randomized controlled trial design to rigorously test the effectiveness of a parenting program on reducing the risk of child maltreatment in sub-Saharan Africa using both observational and self-report assessments. Results provide preliminary evidence of effectiveness of reducing the risk of child maltreatment by improving positive parenting behavior. Further development is required to strengthen program components regarding child behavior management and nonviolent discipline strategies. Future research would benefit from a larger trial with sufficient power to determine program effectiveness.

Imagining Autism: Feasibility of a drama-based intervention on the social, communicative and imaginative behaviour of children with autism

We report the feasibility of a novel, school-based intervention, coined 'Imagining Autism', in which children with autism engage with drama practitioners though participatory play and improvisation in a themed multi-sensory 'pod' resembling a portable, tent-like structure. A total of 22 children, aged 7-12 years, from three UK schools engaged in the 10-week programme. Measures of social interaction, communication and emotion recognition, along with parent and teacher ratings, were collected before and up to 12 months after the intervention. Feasibility was evaluated through four domains: (1) process (recruitment, retention, blinding, inter-rater reliability, willingness of children to engage), (2) resources (space, logistics), (3) management (dealing with unexpected changes, ease of assessment) and (4) scientific (data outcomes, statistical analyses). Overall, the children, parents and teachers showed high satisfaction with the intervention, the amount of missing data was relatively low, key assessments were implemented as planned and evidence of potential effect was demonstrated on several key outcome measures. Some difficulties were encountered with recruitment, test administration, parental response and the logistics of setting up the pod. Following several protocol revisions and the inclusion of a control group, future investigation would be justified to more thoroughly examine treatment effects.

Utility of Bayesian Single-Arm Design in New Drug Application for Rare Cancers in Japan: A Case Study of Phase 2 Trial for Sarcoma

Investigational drugs for rare cancers are often approved based solely on a single-arm phase II trial that primarily evaluates response rate in Japan. Such trials typically use a fixed sample size determined on the basis of the frequentist manner. However, since predicting the speed of patient enrollment is challenging because of the disease rarity, the time needed to complete the enrollment of the fixed number of patients is prolonged in some cases. A Bayesian design without fixing the sample size is useful for single-arm phase II trials of rare cancers. However, the arbitrariness of prior distribution specifications and the frequentist operating characteristics are regulatory issues. We recently started a Bayesian single-arm phase II trial of nivolumab in patients with sarcoma for new drug application in Japan and examined the statistical rationale and design consideration. In the Bayesian design, we specify the minimum and maximum numbers of enrolled patients during the enrollment period and the prior distributions of response rates. Considering these parameters, we obtain the minimum number of responders needed for the positive conclusion of the efficacy of nivolumab for each sample size. Simulation studies demonstrated that the operating characteristics of this design would be acceptable from the frequentist view. The Bayesian design provided an adaptive decision rule for efficacy conclusion for the drug without fixing the sample size. We hope our trial's success will provide a new drug development option for rare cancers in Japan.

Research methods to change clinical practice for patients with rare cancers

Rare cancers are a growing group as a result of reclassification of common cancers by molecular markers. There is therefore an increasing need to identify methods to assess interventions that are sufficiently robust to potentially affect clinical practice in this setting. Methods advocated for clinical trials in rare diseases are not necessarily applicable in rare cancers. This Series paper describes research methods that are relevant for rare cancers in relation to the range of incidence levels. Strategies that maximise recruitment, minimise sample size, or maximise the usefulness of the evidence could enable the application of conventional clinical trial design to rare cancer populations. Alternative designs that address specific challenges for rare cancers with the aim of potentially changing clinical practice include Bayesian designs, uncontrolled n-of-1 trials, and umbrella and basket trials. Pragmatic solutions must be sought to enable some level of evidence-based health care for patients with rare cancers.

The statistical interpretation of pilot trials: should significance thresholds be reconsidered?

BACKGROUND

In an evaluation of a new health technology, a pilot trial may be undertaken prior to a trial that makes a definitive assessment of benefit. The objective of pilot studies is to provide sufficient evidence that a larger definitive trial can be undertaken and, at times, to provide a preliminary assessment of benefit.

METHODS

We describe significance thresholds, confidence intervals and surrogate markers in the context of pilot studies and how Bayesian methods can be used in pilot trials. We use a worked example to illustrate the issues raised.

RESULTS

We show how significance levels other than the traditional 5% should be considered to provide preliminary evidence for efficacy and how estimation and confidence intervals should be the focus to provide an estimated range of possible treatment effects. We also illustrate how Bayesian methods could also assist in the early assessment of a health technology.

CONCLUSIONS

We recommend that in pilot trials the focus should be on descriptive statistics and estimation, using confidence intervals, rather than formal hypothesis testing and that confidence intervals other than 95% confidence intervals, such as 85% or 75%, be used for the estimation. The confidence interval should then be interpreted with regards to the minimum clinically important difference. We also recommend that Bayesian methods be used to assist in the interpretation of pilot trials. Surrogate endpoints can also be used in pilot trials but they must reliably predict the overall effect on the clinical outcome.

Clinical evidence for orphan medicinal products-a cause for concern?

Background

The difficulties associated with organising clinical studies for orphan medicinal products (OMPs) are plentiful. Recent debate on the long-term effectiveness of some OMPs, led us to question whether the initial standards for clinical evidence for OMPs, set by the European Medicines Agency (EMA) at the time of marketing authorization, are too low. Therefore, the aim of this study was to quantitatively evaluate the characteristics and quality of clinical evidence that is presented for OMPs to obtain marketing authorization in Europe, using the new and validated COMPASS tool.

Methods

We quantitatively assessed the characteristics and quality of clinical evidence of the pivotal studies of 64 OMPs as described in the European Public Assessment Report and/or the Scientific Discussion document prepared by the Committee for Human Medicinal Products of the EMA.

Results

The 64 OMPs were altogether authorized for 78 orphan indications, for which 117 studies were identified as 'pivotal’ or 'main’ studies. In approximately two thirds of the studies, the allocation was randomized (64.8%) and a control arm was used (68.5%). Half of the studies applied some type of blinding. Only a minority (26.9%) of the studies included a Quality-of-Life (QoL) related endpoint, of which a third claim an improvement in QoL. Upon analyzing the quality of reporting, we found that some aspects (i.e. the endpoints, the sampling criteria, and the interventions) are well described, whereas other items (i.e. a description of the patients and of potential biases) are not reported for all studies.

Conclusions

In conclusion, the pivotal studies that are the basis for marketing authorization of OMPs are a cause for concern, as they exhibit methodological flaws i.e. the lack of QoL-related endpoints as outcome, lack of blinding in the study design and the use of surrogate endpoints. Additionally, there are shortcomings in the reporting of those studies that complicate the interpretation. A more demanding regulatory process for OMPs is needed to guide evidence-based clinical decision-making.

Experimental designs for small randomised clinical trials: an algorithm for choice

Background

Small clinical trials are necessary when there are difficulties in recruiting enough patients for conventional frequentist statistical analyses to provide an appropriate answer. These trials are often necessary for the study of rare diseases as well as specific study populations e.g. children. It has been estimated that there are between 6,000 and 8,000 rare diseases that cover a broad range of diseases and patients. In the European Union these diseases affect up to 30 million people, with about 50% of those affected being children. Therapies for treating these rare diseases need their efficacy and safety evaluated but due to the small number of potential trial participants, a standard randomised controlled trial is often not feasible. There are a number of alternative trial designs to the usual parallel group design, each of which offers specific advantages, but they also have specific limitations. Thus the choice of the most appropriate design is not simple.

Methods

PubMed was searched to identify publications about the characteristics of different trial designs that can be used in randomised, comparative small clinical trials. In addition, the contents tables from 11 journals were hand-searched. An algorithm was developed using decision nodes based on the characteristics of the identified trial designs.

Results

We identified 75 publications that reported the characteristics of 12 randomised, comparative trial designs that can be used in for the evaluation of therapies in orphan diseases. The main characteristics and the advantages and limitations of these designs were summarised and used to develop an algorithm that may be used to help select an appropriate design for a given clinical situation. We used examples from publications of given disease-treatment-outcome situations, in which the investigators had used a particular trial design, to illustrate the use of the algorithm for the identification of possible alternative designs.

Conclusions

The algorithm that we propose could be a useful tool for the choice of an appropriate trial design in the development of orphan drugs for a given disease-treatment-outcome situation.

Serum IL-17F does not predict poor response to IM IFNβ-1a in relapsing-remitting MS

OBJECTIVE

There is a significant unmet need for serum biomarkers in relapsing-remitting multiple sclerosis (RRMS) that are predictive of therapeutic response to disease-modifying therapies. Following a recent Stanford study which reported that pretreatment levels of serum interleukin (IL)-17F could predict poor response to interferon-β (IFNβ) therapy, we sought to validate the finding using samples from a large clinical trial.

METHODS

The validation cohort included 54 good responders (GR) and 64 poor responders (PR) selected from 762 subjects with RRMS from the IM IFNβ-1a dose comparison study (Avonex study C94-805). Subjects were classified as GR and PR based on the number of relapses, Expanded Disability Status Scale score, and new and enlarging T2 lesions on MRI. Serum samples were assayed for IL-17F using a multiplexed Luminex assay and for IL-17F/F using an ELISA. Replicate aliquots from the Stanford study were also assayed to assure reproducibility of methods.

RESULTS

Median pretreatment and post-treatment serum IL-17F levels were not statistically significantly different between GR and PR, and serum IL-7/IL-17F ratios were also not predictive of response status. Replicate aliquots from the Stanford study showed good correlation to their original cohort (r = 0.77).

CONCLUSIONS

We were unable to validate the finding that serum IL-17F is a predictor of PR in a large independent cohort of subjects with RRMS. Differences in patient populations and methodology might explain the failure to validate the results from the Stanford study.