Before and After StudyLasagna plots to visualize results in surgical studies

- A lasagna plot is a new method to graphically display longitudinal data.
- The lasagna plots gave a clear overview of multiple end points after surgical interventions.
- The lasagna plots demonstrated new observations and improved the interpretation of the results.

BackgroundA lasagna plot is a graphical tool that can display multiple longitudinal outcomes. To our knowledge, lasagna plots have not been used in publications of surgical studies before. The objective of this study was to demonstrate the results of surgical randomized controlled trials (RCTs) with lasagna plots in order to assess whether this can lead to new observations of the data presented in the original studies.Material and MethodsLasagna plots were created with R for an RCT comparing endovascular and open repair for patients with a ruptured abdominal aortic aneurysm (AJAX trial), an RCT comparing laparoscopy or open surgery combined with either fast track or standard care for patients with colon cancer (LAFA trial) and an RCT comparing preoperative biliary drainage and early surgery for patients with pancreatic cancer (DROP trial).ResultsRegarding the AJAX trial, the original article had reported the rate of outcomes at 30 days after repair in two tables. The plots additionally demonstrated the moments of occurrence, increase and decrease of multiple outcomes such as renal replacement therapy and occurrence of death within one plot. These observations were not presented in the original article. The lasagna plots of the LAFA and DROP trial revealed similar new observations on multiple longitudinal outcomes.ConclusionBy revealing new observations of the previously published data, lasagna plots generate new hypotheses and theories regarding the outcomes. As such, lasagna plots may be a useful addition to traditional tables and figures and could improve the interpretation of results.