For the Academy of Neurologic Physical Therapy, 2016 is a landmark year. This year the latest Step conference—IV Step: Prevention, Prediction, Plasticity, and Participation—was convened. A conversation with a colleague at IV Step reminded me of the progress we have made since the III Step meeting in 2005. She recalled that at that time, I had gone to the microphone on several occasions to advocate for the use of standardized outcome measures. The following year the Section on Research established the EDGE Taskforce; soon after which the Academy of Neurologic Physical Therapy (at that time called Neurology Section) took the lead on profession-wide efforts to promote the use of standardized outcome measures. The current issue contains the recommendations of the TBI EDGE Task Force; and recommendations of the StrokEDGE, MS EDGE, and SCI EDGE Task Forces are available on the Academy website. We have good reason to celebrate how far we've come!
While the progress we've made in incorporating standardized outcome measures into our practice is momentous, the message that I took away from some of the IV Step presentations gave me pause. In much the same way that we can be enamored with rehabilitation technologies even when the outcomes associated with them are not superior to those obtained with conventional approaches, we can also become enamored with technology-based outcome measures. For example, one presentation described the impressive changes in an electrophysiologic outcome measure associated with a high-tech intervention. However, the change in functional performance associated with the intervention (which required costly equipment and extensive training to use) was modest and not better than has been reported for more clinically accessible forms of intervention directed at similar outcomes.
At the Rehabilitation Research at NIH: Moving the Field Forward conference earlier this summer, one of the panel discussants related a patient case illustrating the dissociation that can be observed between electrophysiologic and performance-based outcome measures.1 He described how a research colleague applied a transcranial magnetic stimulation intervention in a patient with stroke, and excitedly reported his findings related to the change in the fMRI response. However, those listening to the colleague's report pointed out that the patient's arm remained fixed in a flexion contracture and there was no change in the patient's ability to move the limb. The relationship between physiologic biomarkers and performance-based measures is not always direct. It may seem paradoxical but “[w]hile the effect of an intervention on a biomarker does provide direct evidence regarding biological activity, such evidence could be unreliable regarding effects on true clinical efficacy measures even when the biomarker is strongly correlated with these clinical efficacy measures...”.2 In the final analysis, as the scholar Alfred H. S. Korzybski3 reminds us, “[a] map is not the territory,” and the usefulness of the map depends on how well it reflects the actual territory.
The limitations of biological and physiologic markers of change in the nervous system (ie, change at the body structure and function level4) do not mean that they are without value. These measures can have great potential for helping us understand the mechanisms underlying the changes we engender, or hope to engender, in terms of functional performance (ie, at the activities level4). With that said, few patients get excited about higher values of their electromyographic signals, or the enlargement of their fMRI region of interest—what they want is to be able to use a keyboard more efficiently or take a walk around the block with their grandchildren. In clinical practice (and clinical research), it is important that we emphasize—and measure—the change that is meaningful for our patients. It would be a disservice to our patients to make decisions about evidence for practice based on measures that have little value for them, measures that may be only a shadow of the meaningful measures of change. Perhaps, there is a lesson for us in Aesop's parable of the dog with the bone who sees his reflection in the water and loses the real bone for grasping at its shadow.
1. Malec JF. Effective pathways to evidence for rehabilitation. Panel discussion at: Rehabilitation Research at NIH: Moving the Field Forward; May 26, 2016; Bethesda, MD.
2. Fleming TR, Powers JH. Biomarkers and surrogate endpoints in clinical trials. Stat Med. 2012;31(25):2973–2984.
3. Korzybski A. Science and Sanity: An Introduction to Non-Aristotelian Systems and General Semantics. 5th ed. Brooklyn, NY: Institute of General Semantics; 1994:58.
4. World Health Organization. International Classification of Functioning, Disability and Health: ICF. Geneva, Switzerland: World Health Organization; 2001.