Problem:
Two types of blood pressure medication, warfarin and aspirin, were compared in stroke patients. 170 stroke patients were included in a cross-over trial. Each patient took warfarin for a period, with the administration order at random. 38 stroke patients' blood pressure was reduced while they were on warfarin, and 72 patients were on aspirin. 42 stroke patients did well on both warfarin and aspirin, and 18 stroke patients died of heart attack and failed to complete the trial.
a) Draw a 2 by 2 table Warfarin reduced BP Warfarin No BP Change Total Aspirin reduced BP 42 72 114 Aspirin no BP change 38 18 56 Total 80 90 170
b) Is there any evidence of a difference in the effect between the medications? [Assume the level for statistical significance is 0.05]
c) Write a summary of what the results show.