Inference and Decision Making for 21st-Century Drug Development and Approval

ABSTRACT

The cost and time of pharmaceutical drug development continue to grow at rates that many say are unsustainable. These trends have enormous impact on what treatments get to patients, when they get them and how they are used. The statistical framework for supporting decisions in regulated clinical development of new medicines has followed a traditional path of frequentist methodology. Trials using hypothesis tests of “no treatment effect” are done routinely, and the p-value < 0.05 is often the determinant of what constitutes a “successful” trial. Many drugs fail in clinical development, adding to the cost of new medicines, and some evidence points blame at the deficiencies of the frequentist paradigm. An unknown number effective medicines may have been abandoned because trials were declared “unsuccessful” due to a p-value exceeding 0.05. Recently, the Bayesian paradigm has shown utility in the clinical drug development process for its probability-based inference. We argue for a Bayesian approach that employs data from other trials as a “prior” for Phase 3 trials so that synthesized evidence across trials can be utilized to compute probability statements that are valuable for understanding the magnitude of treatment effect. Such a Bayesian paradigm provides a promising framework for improving statistical inference and regulatory decision making.     

REVIEWS

Bailey, C. E. (Ed.) (2000). Children in therapy: Using the family as a resource. Doherty, W. J. (2001). Take back your marriage: Sticking together in a world that pulls us apart. New York: Guilford. Larson, J. H. (2000). Should we stay together? A scientically proven method for evaluating your relationship and improving its chances for long‐term success. Weiner‐Davis, M. (2001). The divorce remedy: The proven 7‐step program for saving your marriage.     

The Persistent Problem of Colorism: Skin Tone, Status, and Inequality

Colorism is a persistent problem for people of color in the USA. Colorism, or skin color stratification, is a process that privileges light-skinned people of color over dark in areas such as income, education, housing, and the marriage market. This essay describes the experiences of African Americans, Latinos, and Asian Americans with regard to skin color. Research demonstrates that light-skinned people have clear advantages in these areas, even when controlling for other background variables. However, dark-skinned people of color are typically regarded as more ethnically authentic or legitimate than light-skinned people. Colorism is directly related to the larger system of racism in the USA and around the world. The color complex is also exported around the globe, in part through US media images, and helps to sustain the multibillion-dollar skin bleaching and cosmetic surgery industries.     

Use of Technology in Delivering Career Services Worldwide

The authors review the trends in the use of computers in the delivery and support of career guidance and counseling identified at the symposium International Perspectives on Career Development. The papers presented emphasized that 20th‐century computer‐based systems continue to be used, mainly delivered via the World Wide Web. These systems are enhanced through audio, video, graphics, strategies to provide needs assessment, and support by cybercounselors or expert system design. The papers also revealed a new trend: the use of elegant Web sites to store and search immense libraries of resources needed by professionals and clients and to facilitate communication and collaboration among professionals in cyberspace. Concerns, issues, and resources related to many areas, including the readiness of clients to use computer‐based systems, were also raised; existing sources of guidelines are noted.     

Who am I? Concepts of disability and their implications for people with learning difficulties

The relationship between concepts of disability, group membership and self-concept was examined. It was argued that people with learning difficulties have been categorised, by non-disabled people, as 'belonging' to a devalued social group with a rigid boundary based on IQ level. Findings from studies of self-concept have shown little evidence of a sense of belonging. It was suggested that people with learning difficulties may prefer not to identify with this social group because of the negative effect it may have on their self-esteem. The analysis based on intergroup and social identity theories proposed that people with learning difficulties may be encouraged in creating a positive self-concept by abandoning the IQ criterion for social categorisation; softening the boundaries between disabled and non-disabled people; and adopting collective rather than individual strategies for social change.     

Assessing accuracy of a continuous screening test in the presence of verification bias

Summary.  In studies to assess the accuracy of a screening test, often definitive disease assessment is too invasive or expensive to be ascertained on all the study subjects. Although it may be more ethical or cost effective to ascertain the true disease status with a higher rate in study subjects where the screening test or additional information is suggestive of disease, estimates of accuracy can be biased in a study with such a design. This bias is known as verification bias. Verification bias correction methods that accommodate screening tests with binary or ordinal responses have been developed; however, no verification bias correction methods exist for tests with continuous results. We propose and compare imputation and reweighting bias-corrected estimators of true and false positive rates, receiver operating characteristic curves and area under the receiver operating characteristic curve for continuous tests. Distribution theory and simulation studies are used to compare the proposed estimators with respect to bias, relative efficiency and robustness to model misspecification. The bias correction estimators proposed are applied to data from a study of screening tests for neonatal hearing loss.