When compliance fails, which is to blame: the patient or the appliance?

In the early years of my life as an orthodontist I sometimes heard comments about the behavior of patients undergoing treatment. These comments were targeted at patients’ compliance in the use of the orthodontic appliance itself or its accessories, such as intermaxillary elastics, headgear, etc.. Such remarks were often uttered disapprovingly. “That’s a lousy patient. Never wears his headgear,” or “No way, she’ll never wear her removable appliance.” That’s the crux of this editorial. When compliance fails, which is to blame: the patient or the appliance? This issue is deeply rooted in the scientific method and in the design of different clinical trials as well as in how we read and understand research articles. To illustrate this point, try to envisage the following hypothetical scenario. A study is conducted to compare the efficacy of two different treatment protocols. A total of 300 patients are involved in the research and are randomly distributed among three groups. One hundred patients for treatment A, 100 for B and 100 in a control group. These treatments could be, for example, (A) new device for Class II correction and (B) extraoral appliance. In this study, 82 patients completed the treatment in group A (new appliance) and 93 in group B (headgear). The hypothetical results, excluding the control group, are gathered in Table 1. The results of our study show different hypothetical success rates. Treatment A (new appliance) had a success rate of 97.5% while treatment B (headgear) had a success rate of 92.5%. Now comes the intriguing question: Which is the best treatment in light of these results? The answer is clear. Treatment B (headgear), with a 92.5% success rate, apparently proved BETTER than treatment A (new appliance), with a 97.5% success rate. That’s right, the treatment with the lower success rate was the best treatment for Class II correction. Why? The number of individuals who completed the treatment in both groups was different. It was smaller in treatment A (new appliance) than in treatment B (headgear). We have compelling reason to take this difference into account as part of the treatment outcomes. In other words, most people give up on the new appliance because it is unsightly, or very uncomfortable, or because it has some negative feature that leads to lower rates of compliance. This fact should always be weighed when comparing treatments, or even when evaluating a series of cases.