Thesis (Ph. D.)--UCLA, 2007. / Vita. Includes bibliographical references (leaves 330-341).

Thesis (M.A.)--Carleton University, 1991. / Also available in electronic format on the Internet.

Thesis (M.A.) -- University of Tennessee, Knoxville, 2006. / Title from title page screen (viewed on June 12, 2006). Thesis advisor: G. Kurt Piehler. Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (p. 89-97).

This thesis maps the growth of the use of internet technologies in randomised controlled trials in health care and public health, and explores the methodological and ethical issues that arise from their use from the perspective of researchers and participants. Online clinical trials are growing in number, and claim to offer benefits for researchers and participants, providing solutions to some of the inherent problems associated with traditional trials. However, little is known about how many internet-based trials have been conducted, what methodological research has been undertaken, or what impact the new technologies might have on researcher or participant experience. The thesis followed a step-by-step approach, using information science, research synthesis, and qualitative methods. The creation of a database of internet-based clinical trials established that they have grown rapidly in number, use internet technologies primarily to deliver an intervention, predominantly in behavioural, mental health, or life-style public health settings. A two-stage systematic review, comprising a descriptive map and a qualitative synthesis, established what is known about the methods, conduct or participant experience in internet-based trials. A qualitative primary study was then carried out, based on the findings of the review, to further explore the views, attitudes and experiences of researchers, participants and the public, into the motivations, benefits or barriers to taking part in internet-based clinical trials. Themes emerging from the research suggest complex interactions between design and technology, particularly in the area of participant characteristics and choice; convenience versus intrusion; impact of time and place; the pace of change and impact of societal changes in the use of technology. A range of ethical considerations emerged, including the nature of informed consent, ethical approval, and the need for a systematic approach to patient and public involvement. Recommendations are made to help inform and improve research practice in the digital age.

Phase II clinical trials aim to potentially screen out ineffective and identify effective therapies to move forward to randomized phase III trials. Single-arm studies remain the most utilized design in phase II oncology trials, especially in scenarios where a randomized design is simply not practical. Due to concerns regarding excessive toxicity or ineffective new treatment strategies, interim analyses are typically incorporated in the trial, and the choice of statistical methods mainly depends on the type of primary endpoints. For oncology trials, the most common primary objectives in phase II trials include tumor response rate (binary endpoint) and progression disease-free survival (time-to-event endpoint). Interim strategies are well-developed for both endpoints in single-arm phase II trials. The advent of molecular targeted therapies, often with lower toxicity profiles from traditional cytotoxic treatments, has shifted the drug development paradigm into establishing evidence of biological activity, target modulation and pharmacodynamics effects of these therapies in early phase trials. As such, these trials need to address simultaneous evaluation of safety as well as proof-of-concept of biological marker activity or changes in continuous tumor size instead of binary response rates. In this dissertation, we extend a predictive probability design for binary outcomes in the single-arm clinical trial setting and develop two interim designs for continuous endpoints, such as continuous tumor shrinkage or change in a biomarker over time. The two-stage design mainly focuses on the futility stopping strategies, while it also has the capacity of early stopping for efficacy. Both optimal and minimax designs are presented for this two-stage design. The multi-stage design has the flexibility of stopping the trial early either due to futility or efficacy. Due to the intense computation and searching strategy we adopt, only the minimax design is presented for this multi-stage design. The multi-stage design allows for up to 40 interim looks with continuous monitoring possible for large and moderate effect sizes, requiring an overall sample size less than 40. The stopping boundaries for both designs are based on predictive probability with normal likelihood and its conjugated prior distributions, while the design itself satisfies the pre-specified type I and type II error rate constraints. From simulation results, when compared with binary endpoints, both designs well preserve statistical properties across different effect sizes with reduced sample size. We also develop an R package, PPSC, and detail it in chapter four, so that both designs can be freely accessible for use in future phase II clinical trials with the collaborative efforts of biostatisticians. Clinical investigators and biostatisticians have the flexibility to specify the parameters from the hypothesis testing framework, searching ranges of the boundaries for predictive probabilities, the number of interim looks involved and if the continuous monitoring is preferred and so on.

IMPACT (Integrated Management of Physician-Delivered Alcohol Care for Tuberculosis patients) is a randomized, controlled effectiveness trial based in Tomsk, Russia, that assesses the effect of oral naltrexone and brief behavioral counseling on tuberculosis outcomes and alcohol use in 200 patients. Tuberculosis physicians without addiction experience delivered interventions as part of routine care over a 6-month period, focusing on alcohol intake reduction to support successful tuberculosis treatment. We describe design, training, and fidelity monitoring using a Russian and American team of physicians, bilingual coders, and supervisors. Culturally appropriate adaptations, limitations, and implications for future trials are discussed. The clinical trial identification number is NCT00675961. Funding came from the National Institutes of Health and National Institute on Drug Abuse.

IMPACT (Integrated Management of Physician-Delivered Alcohol Care for Tuberculosis patients) is a randomized, controlled effectiveness trial based in Tomsk, Russia, that assesses the effect of oral naltrexone and brief behavioral counseling on tuberculosis outcomes and alcohol use in 200 patients. Tuberculosis physicians without addiction experience delivered interventions as part of routine care over a 6-month period, focusing on alcohol intake reduction to support successful tuberculosis treatment. We describe design, training, and fidelity monitoring using a Russian and American team of physicians, bilingual coders, and supervisors. Culturally appropriate adaptations, limitations, and implications for future trials are discussed. The clinical trial identification number is NCT00675961. Funding came from the National Institutes of Health and National Institute on Drug Abuse.

Superiority clinical trials are often designed with a planned interim analysis for the purpose of sample size re-estimation (SSR) when limited information is available at the start of the trial to estimate the required sample size. Typically these trials are designed with a two-arm internal pilot where subjects are enrolled to both treatment arms prior to the interim analysis. Circumstances may sometimes call for a trial with a single-arm internal pilot (enroll only in the control group). For a dichotomous outcome, Herson and Wittes proposed a SSR method (HW-SSR) that can be applied to single-arm internal pilot trials using an unblinded estimate of the control group outcome rate. Previous evaluations of the HW-SSR method reported conflicting results regarding the impact of the method on the two-sided Type I error rate and power of the final hypothesis test. In this research we evaluate the HW-SSR method under the null and alternative hypothesis in various scenarios to investigate the one-sided Type I error rate and power of trials with a two-arm internal pilot. We find that the one-sided Type I error rate is sometimes inflated and that the power is sometimes reduced. We propose a new method, the Critical Value and Power Adjusted Sample Size Re-estimation (CVPA-SSR) algorithm to adjust the critical value cutoff used in the final Z-test and the power critical value used in the interim SSR formula to preserve the nominal Type I error rate and the desired power. We conduct simulations for trials with single-arm and two-arm internal pilots to confirm that the CVPA-SSR algorithm does preserve the nominal Type I error rate and the desired power. We investigate the robustness of the CVPA-SSR algorithm for trials with single-arm and two-arm internal pilots when the assumptions used in designing the trial are incorrect. No Type I error inflation is observed but significant over- or under-powering of the trial occurs when the treatment effect used to design the trial is misspecified.

Platform trials evaluating multiple treatment arms against a shared control are an efficient alternative to multiple two-arm trials. Motivated by a randomized clinical trial of the effectiveness of two neuroprotection devices during aortic valve surgery against a control, this dissertation addresses two open questions in the optimal design of these trials. First, to explore whether multiplicity adjustments are necessary in a platform design, simulation studies evaluating the operating characteristics of platform designs relative to independent two-arm trials were conducted. Under the global null hypothesis, relative to a set of two-arm trials, we found that platform trials have slightly lower familywise error; however, conditional error rates for an experimental treatment being declared effective given another was declared effective are above the nominal alpha-level. Adjusting for multiplicity reduces familywise error, but has little impact on conditional error. These studies show that multiplicity adjustments are unnecessary in platform trials of unrelated treatments. Second, to determine the optimal approach for comparing delayed entry arms to the shared control, five methods for incorporating historical controls into two-arm trials were applied to the analyses of simulated open platform trials and compared to pooling all controls. We found that when response rates are constant, pooling yields the lowest error and most precise, unbiased estimates. However, if drift occurs, pooling results in type I error inflation or deflation depending on the direction of drift, as well as biased estimates. Although superior to naive pooling, none of the alternatives explored guarantee error control or unbiased estimates in the presence of drift. Thus, only concurrent controls should be used as comparators in the primary analysis of confirmatory studies. Finally, these findings were applied to assess the design and analysis of the neuroprotection trial.