A double blind randomised controlled trail was performed to assess the effect of vitamins on preventing cardiovascular diseases. 250 were given vitamins while 285 were not. Among those who have been given vitamins, 85 developed the disease while only 40 did not develop the disease from those who were not given the vitamins. Please calculate the risk difference (RD) or attributed risk (AR) for vit-intake compared to non-vit-intake?

Question

Quizplus · Accepted Answer

The risk difference (RD) is calculated as the risk in the exposed group minus the risk in the unexposed group. The risk in the vitamin group is 85/250 = 0.34, and the risk in the non-vitamin group is 245/285 = 0.86. Therefore, RD = 0.34 - 0.86 = -0.52.

A Double Blind Randomised Controlled Trail Was Performed to Assess