Fun Fact! One of the first unofficial Randomized Controlled trials (RCT) was done in 1754 to see the effect of treating 12 men with scurvy. They were divided into six pairs and each had different additives in their usual diet. Each pair had a special intervention, with one pair receiving orange and lemons for 6 days of a 14 day trial period. They made a dramatic recovery.
This is how we know citrus fruits treat scurvy.
The first OFFICIAL RCT by modern standards was published in 1948, however. It is a Medical Research Council trial of streptomycin in pulmonary pulmonary tuberculosis (though the whooping cough vaccination trial was started just before it, it was published first).
Evidence based [practice] is the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients. The practice of evidence based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research. By individual clinical expertise we mean the proficiency and judgment that individual clinicians acquire through clinical experience and clinical practice.