If so, the presence of RKF could be an effect modifier of the association of FGF23 with mortality and cardiovascular disease, which may explain the difference in the hazard associated with elevated FGF23 between incident versus prevalent hemodialysis patients, and between short-term versus long-term hemodialysis patients, as well as between hemodialysis patients with versus without RKF. Here, FGF23 is linked to cardiovascular disorder.