WHO Regional Office for Europe's natural experiment studies project: an introduction to the series

Fiscal, legislative and regulatory interventions now comprise the main WHO recommended ‘best-buys’ for preventing and controlling non-communicable diseases (NCDs). Yet these interventions are not well-suited to rigorous study using clinical trials, as they are often not feasible or ethical outside of smaller pilot studies. Currently we estimate that <1 out of every 10 NCD interventions are subject to real-world evaluation, including actions to ban trans-fat, tobacco control measures in the Framework Convention on Tobacco Control, alcohol minimum pricing and sugar-sweetened beverage taxes.1 This lack of impact evaluation obviates learning from what works, where and why. Without evidence it may also render these programmes more vulnerable to challenges from vested interests who seek to oppose them.