Clinical Trials

Clinical Trials: A Practical Guide ■❚❙❘Figure 5. A linear regression line for the systolic blood pressure (SBP) data for the 10 subjects receivinga drug for hypertension.1506SBP (mm Hg)14013012011010090101739458261017394582610173945826101739548261379548Baseline24Time (weeks)68The numbering on the lines refers to the subject’s number in the trial.ConclusionThe key issues when choosing which method of summary measure analysis to use arethe questions you wish to answer and the type of data collected. The summarymeasures chosen need to have a clear clinical relevance and should be deduced at thedesign stage. In most trials, more than one summary measure may be used to analyzerepeated measurement data, to address different aspects of the study question.References1. Diggle PJ, Liang KY, Zeger SL. Analysis of Longitudinal Data. Oxford: Clarendon Press, 1994.2. Brown H, Prescott R. Applied Mixed Models in Medicine. Chichester: John Wiley & Sons, 1999.3. Everitt BS. The analysis of repeated measures: a practical review with examples.Statistician 1995:44:113–35.4. Touloumi G, Pocock SJ, Babiker A, et al. Impact of missing data due to selective dropoutsin cohort studies and clinical trials. Epidemiology 2002:13:347–55.5. Dunn G, Pickles A. Longitudinal data analysis. Overview. In: Armitage P, Colton T, editors.Encyclopedia of Biostatistics. New York: John Wiley & Sons, 1998:2352–63.327