Scott Gavura, BScPhm, MBA, RPh, works in the Ontario cancer system and has a professional interest in improving the cost-effective use of drugs at the population level, primarily focusing on evaluating new drugs. He is a registered pharmacist in Ontario. He blogs on the Science-Based Pharmacy blog which he describes as “Turning an eye on the profession, separating fact from fiction on both sides of the counter”. This post originally appeared on the Science-Based Medicine blog.
One of the most interesting aspects of working as a community-based pharmacist is the insight you gain into the actual effectiveness of the different health interventions. You can see the most elaborate medication regimens developed, and then see what happens when the “rubber really hits the road”: when patients are expected to manage their own treatment plan. Not only do we get feedback from patients, there’s a semi-objective measure we can use — the prescription refill history.
The clinical trial, from where we derive much of our evidence on treatments, is very much an idealized environment. The relationship to the “real world” may be tenuous. Patients in trials are usually highly selected, typically those that are able to comply with the intervention planned. They may need to be free of any other diseases which could complicate evaluation. Patients that qualify for enrollment enter an environment where active monitoring is the norm, and may be far more intense than normal clinical practice. All of these factors mean that trial results may be meaningful, but not completely generalizable to the patient that may eventually be given the intervention. It’s for this reason we use the term “efficacy” to describe clinical trial results, while “effectiveness” is what we’re more interested in: those real-word effects that are far more relevant, yet more elusive to our decision-making. Efficacy measures a drug’s effect on an endpoint, and estimates risk and benefit in a particular setting. Effectiveness adds in real-world tolerance, the ability to tolerate the regimen, and all the other factors that are present when real patients take a drugs under less-than-ideal conditions. Consequently, effectiveness is a much more useful predictor of outcome than efficacy. Unfortunately, measurements of real-world effectiveness, possibly as a “phase 4″ or real-world trial, are rarely conducted. For the rest of Scott’s post click here.
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Scott Gavura, BScPhm, MBA, RPh, works in the Ontario cancer system and has a professional interest in improving the cost-effective use of drugs at the population level, primarily focusing on evaluating new drugs. He is a registered pharmacist in Ontario. He blogs on the 
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