Clinical Trials

❘❙❚■ Chapter 36 | Use of FiguresFigure 10. A line graph showing how mean systolic blood pressure (SBP) changes after randomizationby treatment (bar stands for ± one standard error) (n = 2028).135Treatment ATreatment B130SBP (mm Hg)125120Baseline 6 12 18 24 3036Follow-up (months)Caution should be employed regarding scales. When the length of time betweenobservations is not uniform and the x-axis is not scaled accordingly then thegraph might not reflect the data accurately. Similarly, if two line graphs arecompared then they must be on the same scale, otherwise visual comparisons willbe meaningless.Spaghetti plotsIf we consider the simple situation where we have separate line graphs showingthe PK profile for each individual in a study, these lines could be combined in asingle graph, sometimes called a spaghetti plot (Figure 11). Spaghetti plots arejust several line graphs that have been overlaid. These plots are useful for PK databecause they allow an assessment of the patterns of drug absorption and elimination,and also allow you to examine the between-subject variation. If individual linesare not all in the same direction or do not peak to the same degree then patientsare exhibiting different responses to the drug, and further examination will bewarranted to investigate the reasons for this.420