Efficacy vs Effectiveness

Traditional efficacy trials are not enough to guarantee that an intervention will work in the more diverse population seen in the clinic, according to researchers who evaluated the effectiveness of an inhaled drug combination for chronic obstructive pulmonary disease (COPD) in everyday clinical practice (1).

“Efficacy studies are limited in their usefulness to clinicians as they are often restricted in their inclusion criteria, meaning that they show what the drugs can do in a controlled setting but not necessarily what they can do in the real world,” says Jørgen Vestbo, first author and professor of respiratory medicine at the University of Manchester. In fact, the authors suggest that fewer than 10 percent of COPD patients would normally be eligible for efficacy trials, since they typically exclude anyone with a coexisting condition. The investigators carried out a randomized study in patients under the care of general practitioners, without the frequency, monitoring or strict eligibility criteria of a controlled trial, to allow for the variation in adherence, dosing frequency, and inhaler technique seen in unsupervised patients.

Rather than efficacy under ideal conditions, the trial assessed the real-world effectiveness of an inhaled combination of fluticasone furoate and vilanterol. The results showed that a broad population of COPD patients benefitted from the inhalant combination, without a significantly greater risk of adverse effects. The authors argue in their paper that incorporating effectiveness trials as a standard component of the translational process would provide much clearer evidence on which to base clinical decisions.

“It’s not a question of either/or,” says Vestbo, “Efficacy studies are still needed; however, effectiveness studies are also required to ensure that the drugs have the expected effects in the real world.”