For pure pathogen-killing power, it’s hard to beat a surgeon’s hand scrub. Ask any clinician, and she’ll tell you how thoroughly chlorhexidine disinfects skin. If she’s a microbiologist, she’ll even explain to you the biocide’s mechanism of action–provided you’re still listening. But how would the practice fare, say, as a method of cold and flu prevention on a college campus? Your skepticism here would seem justified. After all, it’s hard to sterilize a cough in the dining hall.
Efficacy and effectiveness. It’s unfortunate their phonetics are so close, because while the terms do refer to relative locations along a continuum, they’re the furthest thing from synonyms, as the ever accumulating literature on the topic will attest.
In this post and the one that follows, I’d like to offer some clarity on efficacy vs. effectiveness and illustrate the value that each type of analysis offers. If nothing else, what emerges should provide an introduction to the concepts for those new to clinical research. But I have a more speculative aim, too. I’d like propose standards for assessing trial technology through each of these lenses. Why? Because while we’ve been asking whether a particular technology does what it’s explicitly designed to do, as we should and must, we may have forgotten to ask a critical follow-up question: Does it improve the pace and reliability of our research?