Christopher S Coffey

University of Iowa, Iowa City, Iowa, United States

Are you Christopher S Coffey?

Claim your profile

Publications (113)603.34 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study was undertaken to determine the prevalence and correlates of cognitive impairment (CI) and neuropsychiatric symptoms (NPS) in early, untreated patients with Parkinson's disease (PD). Both CI and NPS are common in PD and impact disease course and quality of life. However, limited knowledge is available about cognitive abilities and NPS. Parkinson's Progression Markers Initiative (PPMI) is a multi-site study of early, untreated PD patients and healthy controls (HCs), the latter with normal cognition. At baseline, participants were assessed with a neuropsychological battery and for symptoms of depression, anxiety, impulse control disorders (ICDs), psychosis, and apathy. Baseline data of 423 PD patients and 196 HCs yielded no between-group differences in demographic characteristics. Twenty-two percent of PD patients met the PD-recommended screening cutoff for CI on the Montral Cognitive Assessment (MoCA), but only 9% met detailed neuropsychological testing criteria for mild cognitive impairment (MCI)-level impairment. The PD patients were more depressed than HCs (P < 0.001), with twice as many (14% vs. 7%) meeting criteria for clinically significant depressive symptoms. The PD patients also experienced more anxiety (P < 0.001) and apathy (P < 0.001) than HCs. Psychosis was uncommon in PD (3%), and no between-group difference was seen in ICD symptoms (P = 0.51). Approximately 10% of PD patients in the early, untreated disease state met traditional criteria of CI, which is a lower frequency compared with previous studies. Multiple dopaminergic-dependent NPS are also more common in these patients compared with the general population, but others associated with dopamine replacement therapy are not or are rare. Future analyses of this cohort will examine biological predictors and the course of CI and NPS. © 2015 International Parkinson and Movement Disorder Society. © 2015 International Parkinson and Movement Disorder Society.
    Movement Disorders 03/2015; DOI:10.1002/mds.26170 · 5.63 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Medical and health policy decision-makers require improved design and analysis methods for comparative effectiveness research (CER) trials. In CER trials, there may be limited information to guide initial design choices. In general settings, adaptive designs (ADs) have effectively overcome limits on initial information. However, CER trials have fundamental differences from standard clinical trials including population heterogeneity and a vaguer concept of a “minimum clinically meaningful difference”. The objective of this article is to explore the use of a particular form of ADs for comparing treatments within the CER trial context. To achieve this, the authors review the current state of clinical CER. They also identify areas of CER as particularly strong candidates for application of novel AD and illustrate the potential usefulness of the designs and methods for two group comparisons. The authors found that ADs can stabilize power. Furthermore, the designs ensure adequate power for true effects are at least at clinically significant pre-planned effect size, or when variability is larger than expected. The designs allow for sample size savings when the true effect is larger or when variability is smaller than planned. The authors conclude that ADs in CER have great potential to allow trials to successfully and efficiently make important comparisons.
    Clinical Research and Regulatory Affairs 11/2014; DOI:10.3109/10601333.2014.977490
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Objective To determine if asthma control improves in patients who receive physician–pharmacist collaborative management (PPCM) during visits to primary care medical offices.DesignProspective pre–post study of patients who received the intervention in primary care offices for 9 months. The primary outcome was the sum of asthma-related emergency department (ED) visits and hospitalizations at 9 months before, 9 months during, and 9 months after the intervention. Events were analyzed using linear mixed-effects regression. Secondary analysis was conducted for patients with uncontrolled asthma (Asthma Control Test [ACT] less than 20). Additional secondary outcomes included the ACT, the Asthma Quality of Life Questionnaire by Marks (AQLQ-M) scores, and medication changes.InterventionPharmacists provided patients with an asthma self-management plan and education and made pharmacotherapy recommendations to physicians when appropriate.ResultsOf 126 patients, the number of emergency department (ED) visits and/or hospitalizations decreased 30% during the intervention (p=0.052) and then returned to preenrollment levels after the intervention was discontinued (p=0.83). Secondary analysis of patients with uncontrolled asthma at baseline (ACT less than 20), showed 37 ED visits and hospitalizations before the intervention, 21 during the intervention, and 33 after the intervention was discontinued (p=0.019). ACT and AQLQ-M scores improved during the intervention (ACT mean absolute increase of 2.11, AQLQ-M mean absolute decrease of 4.86, p<0.0001) and sustained a stable effect after discontinuation of the intervention. Inhaled corticosteroid use increased during the intervention (p=0.024).Conclusions The PPCM care model reduced asthma-related ED visits and hospitalizations and improved asthma control and quality of life. However, the primary outcome was not statistically significant for all patients. There was a significant reduction in ED visits and hospitalizations during the intervention for patients with uncontrolled asthma at baseline. Our findings support the need for further studies to investigate asthma outcomes achievable with the PPCM model.
    Pharmacotherapy 10/2014; 34(10). DOI:10.1002/phar.1468 · 2.31 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background and Purpose-The Secondary Prevention of Small Subcortical Stroke trial (SPS3) recruited participants meeting clinical and radiological criteria for symptomatic lacunes. Individuals randomized to dual antiplatelet therapy with clopidogrel and aspirin had an unanticipated increase in all-cause mortality compared with those assigned to aspirin. We investigated the factors associated with mortality in this well-characterized population. Methods-We identified independent predictors of mortality among baseline demographic and clinical factors by Cox regression analysis in participants of the SPS3 trial. Separately, we examined the effect on mortality of nonfatal bleeding during the trial. Results-During a mean follow-up of 3.6 years, the mortality rate was 1.78% per year for the 3020 participants (mean age, 63 years). Significant independent predictors of mortality at study entry were age, diabetes mellitus, history of hypertension, systolic blood pressure (hazard ratio [HR], 1.3 per 20 mm Hg increase), serum hemoglobin <13 g/dL (HR, 1.6), renal function (HR, 1.3 per estimated glomerular filtration rate decrease of 20 mL/min), and body mass index (HR, 1.8 per 10 kg/m(2) decrease). Participants with ischemic heart disease (P=0.01 for interaction) and normotensive/prehypertensive participants (P=0.03 for interaction) were at increased risk if assigned to dual antiplatelet therapy. Nonfatal major hemorrhage increased mortality in both treatment arms (HR, 4.5; 95% confidence interval, 3.1-6.6; P<0.001). Conclusions-Unexpected interactions between assigned antiplatelet therapy and each of ischemic heart disease and normal/prehypertensive status accounted for increased mortality among patients with recent lacunar stroke given dual antiplatelet therapy. Despite extensive exploratory analyses, the mechanisms underlying these interactions are uncertain.
    Stroke 08/2014; 45(10). DOI:10.1161/STROKEAHA.114.005789 · 6.02 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Interventional Management of Stroke (IMS) III is a randomized, parallel arm trial comparing the approach of intravenous tissue plasminogen activator followed by endovascular treatment with intravenous tissue plasminogen activator alone in patients with acute ischemic stroke presenting <3 hours of symptom onset. The trial intended to enroll 900 subjects to ensure adequate statistical power to detect an absolute 10% difference in the percentage of subjects with good outcome, defined as modified Rankin Scale score of 0 to 2 at 3 months. In April 2012, after 656 subjects were randomized, further enrollment was terminated by the National Institute of Neurological Disorders and Stroke based on the prespecified criterion for futility using conditional power <20%. Conditional power was defined as the likelihood of finding statistical significance at the end of the study, given the accumulated data to date and with the assumption that a minimum hypothesized difference of 10% truly exists between the 2 groups. The evolution of study data leading to futility determination is described, including the interaction between the unblinded study statisticians and the Data and Safety Monitoring Board in the complex deliberation of analysis results. The futility boundary was crossed at the trial's fourth interim analysis. At this point, based on the conditional power criteria, the Data and Safety Monitoring Board recommended termination of the trial. Even in spite of prespecified interim analysis boundaries, interim looks at data pose challenges in interpretation and decision making, underscoring the importance of objective stopping criteria. Unique identifier: NCT00359424.
    Stroke 04/2014; 45(5). DOI:10.1161/STROKEAHA.113.003925 · 6.02 Impact Factor
  • Journal of the American Society of Hypertension 04/2014; 8(4):e126. DOI:10.1016/j.jash.2014.03.288 · 2.68 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Inflammatory biomarkers predict incident and recurrent cardiac events, but their relationship to stroke prognosis is uncertain. We hypothesized that high-sensitivity C-reactive protein (hsCRP) predicts recurrent ischemic stroke after recent lacunar stroke. Levels of Inflammatory Markers in the Treatment of Stroke (LIMITS) was an international, multicenter, prospective ancillary biomarker study nested within Secondary Prevention of Small Subcortical Strokes (SPS3), a phase III trial in patients with recent lacunar stroke. Patients were assigned in factorial design to aspirin versus aspirin plus clopidogrel, and higher versus lower blood pressure targets. Patients had blood samples collected at enrollment and hsCRP measured using nephelometry at a central laboratory. Cox proportional hazard models were used to calculate hazard ratios (HRs) and 95% confidence intervals (95% CIs) for recurrence risks before and after adjusting for demographics, comorbidities, and statin use. Among 1244 patients with lacunar stroke (mean age, 63.3±10.8 years), median hsCRP was 2.16 mg/L. There were 83 recurrent ischemic strokes (including 45 lacunes) and 115 major vascular events (stroke, myocardial infarction, and vascular death). Compared with the bottom quartile, those in the top quartile (hsCRP >4.86 mg/L) were at increased risk of recurrent ischemic stroke (unadjusted HR, 2.54; 95% CI, 1.30-4.96), even after adjusting for demographics and risk factors (adjusted HR, 2.32; 95% CI, 1.15-4.68). hsCRP predicted increased risk of major vascular events (top quartile adjusted HR, 2.04; 95% CI, 1.14-3.67). There was no interaction with randomized antiplatelet treatment. Among recent lacunar stroke patients, hsCRP levels predict the risk of recurrent strokes and other vascular events. hsCRP did not predict the response to dual antiplatelets. Unique identifier: NCT00059306.
    Stroke 03/2014; 45(3):707-16. DOI:10.1161/STROKEAHA.113.004562 · 6.02 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Adaptive designs are increasingly used in clinical trials. The Drug Information Association’s Adaptive Design Scientific Working Group (ADSWG) works to foster collaboration among regulatory agencies, academia, and pharmaceutical and biotech companies to further the science of adaptive clinical development. The ADSWG Survey Subteam has collected data on the usage of adaptive designs in clinical research from multiple sources, including a recent ADSWG survey regarding the perception and usage of adaptive designs in academia and industry for studies between 2008 and 2011, as well as barriers to usage; a literature review examining publications of adaptive design methodology and usage between 2000 and 2011; and a trial registry review of adaptive design references from 1996 to 2011. The comprehensive results of the ADSWG 2012 survey are provided in this article with comparisons to our previous 2008 survey, the literature and registry reviews, and recent surveys carried out by the US Food and Drug Administration (FDA) and the European Medicines Agency. Results of the ADSWG 2012 survey illustrate that industry and academia are showing more enthusiasm for adaptive trials, accompanied by an increase in the number of trials using designs described as less well understood in the FDA draft guidance on adaptive designs, published in 2010. The increased use of these methods in exploratory trials is consistent with the FDA draft guidance. The survey also identified several examples of successful marketing applications supported by confirmatory trials utilizing adaptive designs that were considered, at least at the time of the draft guidance, as less well understood. While some of the technological barriers to adaptive design usage identified in the 2008 survey are now less common, there are several important persistent barriers to usage. Organizations can help overcome these barriers through education, preplanning, and early engagement in discussions with the regulators.
    Therapeutic Innovation and Regulatory Science 02/2014; DOI:10.1177/2168479014522468
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: With advances in the understanding of the pathophysiology of dystonia, novel therapeutics are being developed. Such therapies will require clinical investigation ranging from exploratory studies to examine safety, tolerability, dosage selection, and preliminary efficacy to confirmatory studies to evaluate efficacy definitively. As dystonia is a rare and complex disorder with clinical and etiological heterogeneity, clinical trials will require careful consideration of the trial design, including enrollment criteria, concomitant medication use, and outcome measures. Given the complexities of designing and implementing efficient clinical trials, it is important for clinicians and statisticians to collaborate closely throughout the clinical development process and that each has a basic understanding of both the clinical and statistical issues that must be addressed. To facilitate designing appropriate clinical trials in this field, we review important general clinical trial and regulatory principles, and discuss the critical components of trials with an emphasis on considerations specific to dystonia. Additionally, we discuss designs used in early exploratory, late exploratory, and confirmatory phases, including adaptive designs.
    Journal of the American Society for Experimental NeuroTherapeutics 11/2013; 11(1). DOI:10.1007/s13311-013-0221-6 · 3.88 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: IMPORTANCE We observed a significant correlation between cerebrospinal fluid (CSF) levels of tau proteins and α-synuclein, but not β-amyloid 1-42 (Aβ1-42), and lower concentration of CSF biomarkers, as compared with healthy controls, in a cohort of entirely untreated patients with Parkinson disease (PD) at the earliest stage of the disease studied so far. OBJECTIVE To evaluate the baseline characteristics and relationship to clinical features of CSF biomarkers (Aβ1-42, total tau [T-tau], tau phosphorylated at threonine 181 [P-tau181], and α-synuclein) in drug-naive patients with early PD and demographically matched healthy controls enrolled in the Parkinson's Progression Markers Initiative (PPMI) study. DESIGN, SETTING, AND PARTICIPANTS Cross-sectional study of the initial 102 research volunteers (63 patients with PD and 39 healthy controls) of the PPMI cohort. MAIN OUTCOMES AND MEASURES The CSF biomarkers were measured by INNO-BIA AlzBio3 immunoassay (Aβ1-42, T-tau, and P-tau181; Innogenetics Inc) or by enzyme-linked immunosorbent assay (α-synuclein). Clinical features including diagnosis, demographic characteristics, motor, neuropsychiatric, and cognitive assessments, and DaTscan were systematically assessed according to the PPMI study protocol. RESULTS Slightly, but significantly, lower levels of Aβ1-42, T-tau, P-tau181, α-synuclein, and T-tau/Aβ1-42 were seen in subjects with PD compared with healthy controls but with a marked overlap between groups. Using multivariate regression analysis, we found that lower Aβ1-42 and P-tau181 levels were associated with PD diagnosis and that decreased CSF T-tau and α-synuclein were associated with increased motor severity. Notably, when we classified patients with PD by their motor phenotypes, lower CSF Aβ1-42 and P-tau181 concentrations were associated with the postural instability-gait disturbance-dominant phenotype but not with the tremor-dominant or intermediate phenotype. Finally, we found a significant correlation of the levels of α-synuclein with the levels of T-tau and P-tau181. CONCLUSIONS AND RELEVANCE In this first report of CSF biomarkers in PPMI study subjects, we found that measures of CSF Aβ1-42, T-tau, P-tau181, and α-synuclein have prognostic and diagnostic potential in early-stage PD. Further investigations using the entire PPMI cohort will test the predictive performance of CSF biomarkers for PD progression.
    08/2013; 70(10). DOI:10.1001/jamaneurol.2013.3861
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: There is a growing interest in therapies that may augment motor recovery that could be initiated in the acute stroke unit and maintained through the rehabilitation period. Homogenization of the currently fragmented stroke clinicometrics is necessary before such multidisciplinary trials can be conducted. The supplementary motor scale of the NIH Stroke Scale (SMS-NIHSS) is a simple and reliable scale for assessing proximal and distal motor function in the upper and lower extremities. We hypothesized that the currently underutilized SMS-NIHSS is a valid tool for assessing motor recovery with prognosticative value. Methods: We performed an analysis of SMS-NIHSS scores recorded in 1,281 patients enrolled in the Trial of ORG 10172 in Acute Stroke Treatment (TOAST). We plotted the probability of a favorable outcome (FO) and very favorable outcome (VFO) at 3 months based on the baseline SMS-NIHSS scores. In order to better study the relationship between SMS-NIHSS and 3-month functional outcome, we performed multivariate logistic regression analyses using both FO and VFO as outcome measures. Analyses were adjusted for potential confounders such as age, sex, side of the lesion, time from symptom onset to emergency room arrival, temperature, systolic blood pressure, blood glucose level and treatment group assignment (ORG 10172 vs. placebo). We also calculated the Spearman correlation coefficient between the SMS-NIHSS, Barthel Index (BI) and Glasgow Outcome Score (GOS) obtained at the 3-month visit. Results: The mean SMS-NIHSS scores were 8.18 at baseline and 4.68 at 3 months. The SMS-NIHSS scores showed a gradual improvement during the first 3 months after stroke. There was a linear relationship between the baseline SMS-NIHSS scores and the probability of an FO or VFO at 3 months. The SMS-NIHSS baseline score was an independent predictor of FO (OR = 0.86; 95% CI 0.84-0.87; p < 0.0001) and VFO (OR = 0.85; 95% CI 0.84-0.87; p < 0.0001) at 3 months after adjusting for confounders. The degree of improvement in the SMS-NIHSS scores from baseline to 3 months was also independently associated with FO and VFO (p < 0.0001). At 3 months, SMS-NIHSS scores showed a strong correlation with the BI (r = -0.70; p < 0.0001) and GOS (r = 0.73; p < 0.0001). Conclusions: The SMS-NIHSS is a valid scale for assessing motor recovery with prognosticative value, and may be sensitive to changes during recovery. Given that the SMS-NIHSS is an extension of the widely accepted NIHSS, it could be easily implemented in trials conducted in a variety of clinical research settings, including acute stroke hospitals and rehabilitation units.
    Cerebrovascular Diseases 07/2013; 36(1):69-73. DOI:10.1159/000351514 · 3.70 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper examines baseline characteristics from a prospective, cluster-randomized trial in 32 primary care offices. Offices were first stratified by percentage of minorities and level of clinical pharmacy services and then randomized into 1 of 3 study groups. The only differences between randomized arms were for marital status (P=.03) and type of insurance coverage (P<.001). Blood pressures (BPs) were similar in Caucasians and minority patients, primarily blacks, who were hypertensive at baseline. On multivariate analyses, patients who were 65 years and older had higher systolic BP (152.4±14.3 mm Hg), but lower diastolic BP (77.3±11.8 mm Hg) compared with those younger than 65 years (147.4±15.0/88.6±10.6 mm Hg, P<.001 for both systolic and diastolic BP). Other factors significantly associated with higher systolic BP were a longer duration of hypertension (P=.04) and lower basal metabolic index (P=.011). Patients with diabetes or chronic kidney disease had a lower systolic BP than those without these conditions (P<.0001). BP was similar across racial and socioeconomic groups for patients with uncontrolled hypertension in primary care, suggesting that patients with uncontrolled hypertension and an established primary care relationship likely have different reasons for poor BP control than other patient populations.
    Journal of Clinical Hypertension 06/2013; 15(6):404-12. DOI:10.1111/jch.12091 · 2.36 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background Migraine is one of the most common health problems for children and adolescents. If not successfully treated, it can impact patients and families with significant disability due to loss of school, work, and social function. When headaches become frequent, it is essential to try to prevent the headaches. For children and adolescents, this is guided by extrapolation from adult studies, a limited number of small studies in children and adolescents and practitioner preference. The aim of the Childhood and Adolescent Migraine Prevention (CHAMP) study is to determine the most effective preventive agent to use in children and adolescents. MethodsCHAMP is a double-blinded, placebo-controlled, multicenter, comparative effectiveness study of amitriptyline and topiramate for the prevention of episodic and chronic migraine, designed to mirror real-world practice, sponsored by the US National Institute of Neurological Disorders and Stroke/National Institutes of Health (U01NS076788). The study will recruit 675 subjects between the ages of 8 and 17 years old, inclusive, who have migraine with or without aura or chronic migraine as defined by the International Classification of Headache Disorders, 2nd Edition, with at least 4 headaches in the 28 days prior to randomization. The subjects will be randomized in a 2:2:1 (amitriptyline: topiramate: placebo) ratio. Doses are weight based and will be slowly titrated over an 8-week period to a target dose of 1 mg/kg of amitriptyline and 2 mg/kg of topiramate. The primary outcome will be a 50% reduction in headache frequency between the 28-day baseline and the final 28 days of treatment (weeks 20-24). Conclusions The goal of the CHAMP study is to obtain level 1 evidence for the effectiveness of amitriptyline and topiramate in the prevention of migraine in children and adolescents. If this study proves to be positive, it will provide information to the practicing physician as how to best prevent migraine in children and adolescents and subsequently improve the disability and outcomes.
    Headache The Journal of Head and Face Pain 05/2013; 53(5). DOI:10.1111/head.12105 · 2.94 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: Studies have demonstrated that physician/pharmacist collaboration can improve management of chronic conditions. OBJECTIVE: The purpose of this study was to determine whether a correlation exists between existing clinical pharmacy services within a practice-based research network (PBRN) and provider attitudes and beliefs regarding implementing a new pharmacy intervention based on the Theory of Planned Behavior (TPB). METHODS: A validated survey was completed by one clinical pharmacist from each office. This instrument evaluated the current clinical pharmacy services provided in the medical office. TPB instruments were developed that measured beliefs concerning implementation of a clinical pharmacy intervention for either blood pressure or asthma. The pharmacy services and TPB surveys were then administered to physicians and pharmacists in 32 primary care offices throughout the United States. RESULTS: Physicians returned 321 (35.9%) surveys, while pharmacists returned 40 (75.5%). The Cronbach's alpha coefficients generally ranged from 0.65 to 0.98. TPB subscale scores were lower in offices rated with lower pharmacy service scores, but these differences were not statistically significant. There was no correlation between clinical pharmacy service score and providers' TPB subscale scores. In both the hypertension and asthma groups, pharmacists scores were significantly higher than physicians' scores on the attitudes subscale in the multivariate analysis (P < 0.001 and P < 0.05, respectively). CONCLUSIONS: Pharmacists consistently scored higher than physicians on the TPB, indicating that they felt the hypertension or asthma intervention would be more straightforward for them to implement than did physicians. There was no significant correlation between clinical pharmacy service scores and attitudes toward implementing a future physician/pharmacist collaborative intervention using the TPB. Future studies should investigate the ability of the TPB instrument to predict implementation of a similar intervention in offices of physicians never exposed to clinical pharmacy services.
    Research in Social and Administrative Pharmacy 03/2013; 9(6). DOI:10.1016/j.sapharm.2013.01.003 · 2.35 Impact Factor
  • Leslie A McClure, Christopher S Coffey, George Howard
    [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: For studies with two-by-two factorial designs, the complexity of determining an appropriate futility analysis plan is increased as compared to studies where patients are randomized to one treatment. Issues that must be addressed include the possibility of a significant interaction and the need to determine how to proceed given evidence of futility in one arm. Suggested approaches include a two-stage plan, which first assesses futility of the interaction term and proceeds to examine the main effects, given sufficient evidence that no interaction is present, and variations on one-stage plans, which assume the trial will not be stopped for futility in the interaction. PURPOSE: To discuss different approaches to monitoring futility in two-by-two factorial clinical trials and compare their properties. METHODS: We utilized a simulation study, designed to mimic the Secondary Prevention of Small Subcortical Strokes (SPS3) Study, to determine which approach to monitoring futility in two-by-two factorial studies had the most desirable statistical properties. RESULTS: We found that in most scenarios typical of clinical trials, monitoring futility in each arm simultaneously was superior to or as good as monitoring the interaction and then assessing futility in each arm only when the interaction was deemed futile. Monitoring each arm simultaneously lead to early stopping more often when no treatment effect was present, and lower average sample numbers (ASNs). The exception to this was the unlikely case when a qualitative interaction was present. LIMITATIONS: We assumed that one-sided tests were to be performed, and only assessed some of the possible methods for monitoring futility under the study design. CONCLUSIONS: Futility monitoring in two-by-two factorial studies should proceed by assessing each arm simultaneously, rather than monitoring the interaction first. If sizeable interactions are anticipated, study design, rather than study monitoring, should account for this.
    Clinical Trials 02/2013; 10(2). DOI:10.1177/1740774512474374 · 1.94 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The clinical trials community has a never-ending search for dependable and reliable ways to improve clinical research. This exploration has led to considerable interest in adaptive clinical trial designs, which provide the flexibility to adjust trial characteristics on the basis of data reviewed at interim stages. Statisticians and clinical investigators have proposed or implemented a wide variety of adaptations in clinical trials, but specific approaches have met with differing levels of support. Within industry, investigators are actively exploring the benefits and pitfalls associated with adaptive designs (ADs). For example, a Drug Information Association (DIA) working group on ADs has engaged regulatory agencies in discussions. Many researchers working on publicly funded clinical trials, however, are not yet fully engaged in this discussion. We organized the Scientific Advances in Adaptive Clinical Trial Designs Workshop to begin a conversation about using ADs in publicly funded research. Held in November of 2009, the 1&frac12;-day workshop brought together representatives from the National Institutes of Health (NIH), the Food and Drug Administration (FDA), the European Medicines Agency (EMA), the pharmaceutical industry, nonprofit foundations, the patient advocacy community, and academia. The workshop offered a forum for participants to address issues of ADs that arise at the planning, designing, and execution stages of clinical trials, and to hear the perspectives of influential members of the clinical trials community. The participants also set forth recommendations for guiding action to promote the appropriate use of ADs. These recommendations have since been presented, discussed, and vetted in a number of venues including the University of Pennsylvania Conference on Statistical Issues in Clinical Trials and the Society for Clinical Trials annual meeting. To provide a brief overview of ADs, describe the rationale behind conducting the workshop, and summarize the main recommendations that were produced as a result of this workshop. There is a growing interest in the use of adaptive clinical trial designs. However, a number of logistical barriers need to be addressed in order to obtain the potential advantages of an AD. Currently, the pharmaceutical industry is well ahead of academic trialists with respect to addressing these barriers. Academic trialists will need to address important issues such as education, infrastructure, modifications to existing funding models, and the impact on Data and Safety Monitoring Boards (DSMB) in order to achieve the possible benefits of adaptive clinical trial designs.
    Clinical Trials 12/2012; 9(6):671-80. DOI:10.1177/1740774512461859 · 1.94 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Lacunar infarcts are a frequent type of stroke caused mainly by cerebral small-vessel disease. The effectiveness of antiplatelet therapy for secondary prevention has not been defined. We conducted a double-blind, multicenter trial involving 3020 patients with recent symptomatic lacunar infarcts identified by magnetic resonance imaging. Patients were randomly assigned to receive 75 mg of clopidogrel or placebo daily; patients in both groups received 325 mg of aspirin daily. The primary outcome was any recurrent stroke, including ischemic stroke and intracranial hemorrhage. The participants had a mean age of 63 years, and 63% were men. After a mean follow-up of 3.4 years, the risk of recurrent stroke was not significantly reduced with aspirin and clopidogrel (dual antiplatelet therapy) (125 strokes; rate, 2.5% per year) as compared with aspirin alone (138 strokes, 2.7% per year) (hazard ratio, 0.92; 95% confidence interval [CI], 0.72 to 1.16), nor was the risk of recurrent ischemic stroke (hazard ratio, 0.82; 95% CI, 0.63 to 1.09) or disabling or fatal stroke (hazard ratio, 1.06; 95% CI, 0.69 to 1.64). The risk of major hemorrhage was almost doubled with dual antiplatelet therapy (105 hemorrhages, 2.1% per year) as compared with aspirin alone (56, 1.1% per year) (hazard ratio, 1.97; 95% CI, 1.41 to 2.71; P<0.001). Among classifiable recurrent ischemic strokes, 71% (133 of 187) were lacunar strokes. All-cause mortality was increased among patients assigned to receive dual antiplatelet therapy (77 deaths in the group receiving aspirin alone vs. 113 in the group receiving dual antiplatelet therapy) (hazard ratio, 1.52; 95% CI, 1.14 to 2.04; P=0.004); this difference was not accounted for by fatal hemorrhages (9 in the group receiving dual antiplatelet therapy vs. 4 in the group receiving aspirin alone). Among patients with recent lacunar strokes, the addition of clopidogrel to aspirin did not significantly reduce the risk of recurrent stroke and did significantly increase the risk of bleeding and death. (Funded by the National Institute of Neurological Disorders and Stroke and others; SPS3 number, NCT00059306.).
    New England Journal of Medicine 08/2012; 367(9):817-25. DOI:10.1056/NEJMoa1204133 · 54.42 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Adaptive designs allow planned modifications based on data accumulating within a study. The promise of greater flexibility and efficiency stimulates increasing interest in adaptive designs from clinical, academic, and regulatory parties. When adaptive designs are used properly, efficiencies can include a smaller sample size, a more efficient treatment development process, and an increased chance of correctly answering the clinical question of interest. However, improper adaptations can lead to biased studies. A broad definition of adaptive designs allows for countless variations, which creates confusion as to the statistical validity and practical feasibility of many designs. Determining properties of a particular adaptive design requires careful consideration of the scientific context and statistical assumptions. We first review several adaptive designs that garner the most current interest. We focus on the design principles and research issues that lead to particular designs being appealing or unappealing in particular applications. We separately discuss exploratory and confirmatory stage designs in order to account for the differences in regulatory concerns. We include adaptive seamless designs, which combine stages in a unified approach. We also highlight a number of applied areas, such as comparative effectiveness research, that would benefit from the use of adaptive designs. Finally, we describe a number of current barriers and provide initial suggestions for overcoming them in order to promote wider use of appropriate adaptive designs. Given the breadth of the coverage all mathematical and most implementation details are omitted for the sake of brevity. However, the interested reader will find that we provide current references to focused reviews and original theoretical sources which lead to details of the current state of the art in theory and practice.
    Trials 08/2012; 13(1):145. DOI:10.1186/1745-6215-13-145 · 2.12 Impact Factor
    This article is viewable in ResearchGate's enriched format
  • [Show abstract] [Hide abstract]
    ABSTRACT: Object The authors hypothesized that cooling before evacuation of traumatic intracranial hematomas protects the brain from reperfusion injury and, if so, further hypothesized that hypothermia induction before or soon after craniotomy should be associated with improved outcomes. Methods The National Acute Brain Injury Study: Hypothermia I (NABIS:H I) was a randomized multicenter clinical trial of 392 patients with severe brain injury treated using normothermia or hypothermia for 48 hours with patients reaching 33°C at 8.4 ± 3 hours after injury. The National Acute Brain Injury Study: Hypothermia II (NABIS:H II) was a randomized, multicenter clinical trial of 97 patients with severe brain injury treated with normothermia or hypothermia for 48 hours with patients reaching 35°C within 2.6 ± 1.2 hours and 33°C within 4.4 ± 1.5 hours of injury. Entry and exclusion criteria, management, and outcome measures in the 2 trials were similar. Results In NABIS:H II among the patients with evacuated intracranial hematomas, outcome was poor (severe disability, vegetative state, or death) in 5 of 15 patients in the hypothermia group and in 9 of 13 patients in the normothermia group (relative risk 0.44, 95% CI 0.22-0.88; p = 0.02). All patients randomized to hypothermia reached 35°C within 1.5 hours after surgery start and 33°C within 5.55 hours. Applying these criteria to NABIS:H I, 31 of 54 hypothermia-treated patients reached a temperature of 35°C or lower within 1.5 hours after surgery start time, and the remaining 23 patients reached 35°C at later time points. Outcome was poor in 14 (45%) of 31 patients reaching 35°C within 1.5 hours of surgery, in 14 (61%) of 23 patients reaching 35°C more than 1.5 hours of surgery, and in 35 (60%) of 58 patients in the normothermia group (relative risk 0.74, 95%, CI 0.49-1.13; p = 0.16). A meta-analysis of 46 patients with hematomas in both trials who reached 35°C within 1.5 hours of surgery start showed a significantly reduced rate of poor outcomes (41%) compared with 94 patients treated with hypothermia who did not reach 35°C within that time and patients treated at normothermia (62%, p = 0.009). Conclusions Induction of hypothermia to 35°C before or soon after craniotomy with maintenance at 33°C for 48 hours thereafter may improve outcome of patients with hematomas and severe traumatic brain injury. Clinical trial registration no.: NCT00178711.
    Journal of Neurosurgery 07/2012; 117(4):714-20. DOI:10.3171/2012.6.JNS111690 · 3.15 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: When planning clinical trials, decisions regarding sample size are often based on educated guesses of parameters, which may in fact prove to be over- or under-estimates. For example, after initiation of the SPS3 study, published data indicated that the recurrent stroke rates might be lower than initially planned for the study. Failure to account for this could result in an under-powered study. Thus, we performed a sample size re-estimation, and describe the experience herein. We evaluated different scenarios based on a re-estimated overall event rate, including increasing the sample size and increasing the follow-up time, to determine their impact on both type I error and the power to detect the initially planned treatment difference. We found that by increasing the sample size from 2500 to 3000 and by following the patients for one year after the end of recruitment, we would maintain our planned type I error rate, and increase the power to detect the prespecified clinically meaningful difference to between 67% and 87%, depending on the rate of recruitment. We successfully implemented this unplanned design modification in the SPS3 study, in order to allow for sufficient power to detect the planned treatment differences. CLINICAL TRIALS REGISTRATION INFORMATION: Clinical Trials Registration - Unique identifier: NCT00059306.
    Contemporary clinical trials 06/2012; 33(5):1088-93. DOI:10.1016/j.cct.2012.06.007 · 1.51 Impact Factor

Publication Stats

3k Citations
603.34 Total Impact Points


  • 2010–2014
    • University of Iowa
      • Department of Biostatistics
      Iowa City, Iowa, United States
  • 2012
    • University of Texas Health Science Center at San Antonio
      • School of Nursing
      San Antonio, TX, United States
  • 2001–2010
    • University of Alabama at Birmingham
      • Department of Biostatistics
      Birmingham, Alabama, United States
    • Baylor College of Medicine
      Houston, Texas, United States
  • 2009
    • Morehouse School of Medicine
      • Department of Surgery
      Atlanta, Georgia, United States
  • 2008
    • Kansas State University
      • Department of Statistics
      Manhattan, KS, United States
  • 2005
    • University of Alabama
      Tuscaloosa, Alabama, United States
  • 2004
    • University of Toronto
      • Division of Cardiology
      Toronto, Ontario, Canada
  • 2003
    • University of Washington Seattle
      • Department of Medicine
      Seattle, WA, United States
  • 2002
    • Centers for Disease Control and Prevention
      • Epidemiology and Analysis Program Office
      Druid Hills, GA, United States
  • 2000
    • Vanderbilt University
      Nashville, Michigan, United States
  • 1999
    • University of North Carolina at Chapel Hill
      North Carolina, United States