Because sometimes we have good reasons to believe something works even without an RCT, and it would be unethical to withhold such treatment. (Not to mention tha

Because sometimes we have good reasons to believe something works even without an RCT, and it would be unethical to withhold such treatment. (Not to mention that there is a continuum of RCT quality, so it's unclear what would even count and "proven".) The classic tongue-in-cheek example is parachutes: > Objectives: To determine whether parachutes are effective in preventing major trauma related to gravitational challenge. > Design: Systematic review of randomised controlled trials. > Main outcome measure: Death or major trauma, defined as an injury severity score > 15. > Results: We were unable to identify any randomised controlled trials of parachute intervention. > Conclusions: As with many interventions intended to prevent ill health, the effectiveness of parachutes has not been subjected to rigorous evaluation by using randomised controlled trials. Advocates of evidence based medicine have criticised the adoption of interventions evaluated by using only observational data. We think that everyone might benefit if the most radical protagonists of evidence based medicine organised and participated in a double blind, randomised, placebo controlled, crossover trial of the parachute. https://www.bmj.com/content/327/7429/1459 https://www.bmj.com/content/327/7429/1459