Intention to treat and per protocol analysis in clinical trials

Nephrology (Carlton). 2020 Jul;25(7):513-517. doi: 10.1111/nep.13709. Epub 2020 Mar 15.


In clinical epidemiology, experimental studies usually take the form of randomized controlled clinical trials (RCTs). The data analysis of an RCT can be performed by using two complementary strategies, that is according to the intention to treat (ITT) principle and the per protocol (PP) analysis. By using the ITT approach, investigators aim to assess the effect of assigning a drug whereas by adopting the PP analysis, researchers investigate the effect of receiving the assigned treatment, as specified in the protocol. Both ITT and PP analyses are essentially valid but they have different scopes and interpretations dependent on the context.

Keywords: intention to treat analysis; per protocol analysis; randomized clinical trials.

Publication types

  • Review

MeSH terms

  • Clinical Protocols / standards
  • Humans
  • Intention to Treat Analysis / methods*
  • Randomized Controlled Trials as Topic / methods*
  • Reproducibility of Results