Is the relationship between blood pressure and cardiovascular risk dependent on body mass index?

The relationship between blood pressure and cardiovascular mortality according to body mass index has been analyzed in two French prospective studies: the Paris Prospective Study, composed of 7,704 men aged 40-53 years examined in 1967-1972, and the Investigations Pré-Cliniques Study, made up of 19,618 men aged 40-69 years who underwent a checkup in 1970-1980. In the Paris Prospective Study, during a mean follow-up of 11.2 years, 241 cardiovascular deaths occurred, while in the Investigations Pré-Cliniques Study, with a mean follow-up of 7.6 years, 262 cardiovascular deaths occurred. A Cox survival analysis was performed on the data of each study to test the interaction of blood pressure and body mass index in the prediction of cardiovascular risk. Both analyses demonstrate a significant negative interaction, suggesting that a decreasing trend of the relative risk of cardiovascular death with increasing body mass index is better supported by the data than a constant relative risk. These results might have some bearing on the problem of the management of hypertension in overweight subjects.