a. Prevalence of mild or greater aortic regurgitation by duration of exposure compared with controls. Adapted from data presented in Jollis, et al (reference ). b. Rationale for present study using data from figure 2a. The controls are considered to provide an estimate of the background or baseline risk of AR prior to exposure (shown in dark grey). Prevalent cases beyond this estimated background rate were considered to have arisen during the period of drug exposure, thus providing an estimate of incidence (white portion of bars).