Spineline - September/October 2017

Introduction

A primary goal of spine care clinicians is to practice evidence-based medicine to maximize the chances of a favorable outcome for their patients. Pain, a subjective experience, is the reason most patients consult spine specialists. When patients improve, we usually attribute the decreased pain to the specific effect of the treatment. But there are other reasons patients might feel better that include the natural history of the condition, regression to or toward the mean, and the placebo response. These factors should be considered when we assess a good response to treatment and when we evaluate the literature.

Efficacy versus Effectiveness

The distinction between efficacy and effectiveness is useful when interpreting the literature and considering the reasons patients feel better. Efficacy is the superiority of an intervention compared to a placebo as demonstrated in a randomized controlled trial (RCT) under ideal conditions. 1, 2 The research subjects are tightly selected, the clinicians are specially trained and there are usually no concurrent interventions. 1 Put another way, the specific efficacy of the treatment being tested is the overall response to treatment minus the placebo effect and other nonspecific factors mentioned above. 3

Effectiveness, on the other hand, is the overall beneficial effect of a treatment compared to baseline. It is what we aim for in clinical work. In research, effectiveness asks if the treatment is likely to work in a real-world setting. 1 The research setting is an everyday clinical setting with a heterogeneous subject population such as would be seen in practice and there might well be concurrent interventions. 1 Effectiveness includes the specific effect of the treatment, the placebo effect, regression to the mean, and in a research setting, perhaps the Hawthorne effect.

It follows then, that in an RCT, if the treatment and the placebo groups demonstrate similar good results, it can be said that there is no proven efficacy, but since both groups show improvement, there is “proven” effectiveness. Two studies on acupuncture for chronic low back pain (CLBP) illustrate this concept. 2 In each, there were three arms: true acupuncture, sham acupuncture and treatment as usual (TAU). True and sham acupuncture produced roughly the same good outcome, and both were significantly better that TAU. So, true acupuncture did not demonstrate efficacy (no difference from sham). However, because but both sham and true acupuncture were better than TAU, the studies demonstrated effectiveness.

Some Reasons Patients Feel Better

Specific Effect of Treatment

Medical practice should be based on the best available published evidence, ie, results of one or more RCTs. We presume, and it is likely so, that the most probable reason for improvement in an RCT is the specific effect of the treatment. RCTs require very tightly controlled conditions, specially trained providers, and more.

Yet even in such a well-controlled setting, a meaningful number of subjects randomized to a placebo group also improve. It might be instructive to look at some of the explanations for the improvement in research subjects who receive placebo and patients who receive ineffective or unproven treatments.