We thank Drs. Thorp, Kalantar-Zadeh, and Kopple for their interest in our study, in which we showed that increased baseline BMI is a strong risk factor for ESRD. They questioned whether persons with CKD who are obese have paradoxically better survival than those who are not obese and whether what has been called "reverse epidemiology" could explain our findings.

We would like to emphasize that our study was not limited only to those persons with baseline CKD. Overall, 1036 out of 1471 cases of ESRD developed among individuals who did not have baseline CKD (defined as an estimated glomerular filtration rate of <60 mL/min per 1.73 m², or proteinuria or hematuria by dipstick urinalysis). In the overall cohort, as expected, those with increased BMI had a higher risk for death from any cause (Table).

We also point out that increased BMI remained a risk factor for mortality in the subgroup of persons who had baseline CKD (Table). As shown in Table 3 of our paper, increased BMI was a strong risk factor for ESRD among those with and without baseline CKD. Together, these data strongly argue against the presence of important survival bias as an explanation for our findings.