Lead-time bias in studies of cinacalcet prescriptions.

Observational studies have suggested a link between higher serum phosphate, calcium, parathyroid hormone levels, and cardiovascular mortality. The administration of cinacalcet has proven efficient in the treatment of secondary hyperparathyroidism among hemodialysis patients. In an observational study by Block et al., cinacalcet treatment is associated with a much improved all-cause and cardiovascular mortality. However, the results should be interpreted cautiously, as observational studies may be influenced by bias. This Commentary discusses the role of some common potential biases.