On design, methodology and analysis: a randomized controlled trial of radiocontrast media

Barrett, Brendan (1991) On design, methodology and analysis: a randomized controlled trial of radiocontrast media. Masters thesis, Memorial University of Newfoundland.

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Abstract

The preamble to this thesis describes the outline of a randomized trial which was performed to compare the incidence of adverse reactions to ionic high-osmolar and nonionic low-osmolar radiographic contrast media given by intravenous injection or during cardiac catheterization. The objective of the thesis itself is to describe the design, performance and analysis of this trial, while discussing methodologic issues that arose and flaws that occurred. The thesis will explore the consequences of the flaws and will seek to indicate how these might have been avoided or how they may be best dealt with now that they have occurred. -- Chapter 1 provides a background description of radiocontrast media, the history of their development, and an explanation of some terms which are used in relation to contrast throughout the text. -- Chapter 2 describes the scientific rationale for the study to compare the toxicity of ionic high-osmolar and nonionic contrast media. The literature review which forms the basis of this chapter was performed after the study had been completed. However, it is meant to indicate the sort of review which should precede the design of any substantial scientific research. -- Chapter 3 describes the research questions which were posed. This chapter also outlines the relationship .between the questions, existing knowledge about the toxicity of contrast media, and a proposed strategy for the future use of these media. -- Chapter 4 deals with the overall design of the trial and discusses the rationale for the choice of study population and interventions. -- Chapter 5 is concerned with the processes of randomization and blinding that were employed in the trial. There were several deficiencies in the methods of the trial at this point. These are described, along with their possible consequences. Reference is made to methods which would have been more appropriate. -- Chapter 6 discusses the choice of outcomes for the trial. Once again there were flaws in the methods. These are explored in this chapter. The handling of events is also discussed. The analysis and statistical methods used in the trial are discussed in Chapter 7. -- Chapter 8 provides a general review of the methods of economic analyses of health programs. The chapter also discusses some existing economic analyses of the use of contrast media and outlines a proposed economic analysis which will use data from the trial described here. Chapter 9 discusses some ethical issues which arose in relation to the current study. -- Chapter 10 summarizes the major methodological issues which were considered in the thesis.

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