Lag-censoring analysis: lights and shades.

'Intention-to-treat' (ITT) analysis is the recommended approach for the data analysis of randomized clinical trials (RCT). ITT analysis considers patients in the active or in the control arm as originally allocated by randomization, independently of their actual adherence to the assigned treatment. Lag-censoring analysis is a statistical method which takes into account the compliance of patients to the study protocol because the investigator censors a patient when or shortly after he/she stops the treatment being tested. Herein we describe the methodology underlying lag-censoring analysis in general terms and by considering the application of this technique in the analysis of a large RCT in haemodialysis patients, the Evaluation of Cinacalcet Hydrochloride Therapy to Lower Cardiovascular Events (EVOLVE) trial. Use and misuse of this technique are discussed.