Asking questions changes health-related behavior: an updated systematic review and meta-analysis

OBJECTIVES: The question-behavior effect (QBE) refers to whether asking people questions can result in changes in behavior. Such changes in behavior can lead to bias in trials. This study aims to update a systematic review of randomized controlled trials investigating the QBE, in light of several large preregistered studies being published. STUDY DESIGN AND SETTING: A systematic search for newly published trials covered 2012 to July 2018. Eligible trials randomly allocated participants to measurement vs. non-measurement control conditions or to different forms of measurement. Studies that reported health-related behavior as outcomes were included. RESULTS: = 54%). In an analysis restricted to studies with a low risk of bias, the QBE remained small but significant. There was positive evidence of publication bias. CONCLUSION: This update shows a small but significant QBE in trials with health-related outcomes but with considerable unexplained heterogeneity. Future trials with lower risk of bias are needed, with preregistered protocols and greater attention to blinding.