On "Diagnosis of fall risk in Parkinson disease..." Dibble et al. Phys Ther. 2008;88:323-332.

Dibble et al (1) have addressed an important question regarding the methods used for determining the risk for falling in patients with Parkinson disease. My reason for writing this letter is not to take issue with their methods and findings, but rather to raise a question about some of the terminology that was used. In this article, several terms and phrases were used that link the concept of risk with the concept of diagnosis--for example, "diagnosis of fall risk," "fall risk diagnosis," and "ruling out a diagnosis of fall risk." The question is whether doing so is a good idea.

Let's first take a look at definitions for each of the concepts. According to Fletcher and colleagues in their textbook, Clinical Epidemiology: The Essentials, (2) risk is described as "the likelihood that people who are exposed to certain factors ('risk factors') will subsequently develop a particular disease," and risk factors are defined as "characteristics that are associated with an increased risk of becoming diseased." The definition of the word "diagnosis" is a bit messy, in part because the word has 2 quite different meanings, 1 referring to the diagnostic process, and the other to the diagnostic label. A common understanding of the connection between the 2 meanings is that (1) the outcome of the diagnostic process might be the assignment of a diagnostic label, and (2) the patient has the disease or condition specified by the label.

Now let's consider the paradox created by some of the wording used in this article. If a diagnosis is attached to a condition that a patient already has, why would we need to consider the risk of developing the condition? If risk is the likelihood of developing a condition, not a condition per se, can it really be said to be diagnosed? The authors of this article note that several other investigators (3-6) have "called for alternative means of diagnosing fall risk." Although the authors of the cited articles do suggest that alternative means are needed, none of them uses the word "diagnosis" in conjunction with the process of either quantifying risk or identifying risk factors. Given the "risk" for confusion, perhaps it would be useful to disentangle the concepts of risk and diagnosis by using terms like "identification" and "estimation" when referring to risk factors and risk, respectively, instead of using the word "diagnosis."

Barbara J Norton

BJ Norton, PT, PhD, is Associate Professor for the Program in Physical Therapy, Washington University, in St Louis, Mo.

This letter was posted as a Rapid Response on March 14, 2008, at www.ptjournal.org.

References

(1) Dibble LE, Christensen J, Ballard DJ, Foreman KB. Diagnosis of fall risk in Parkinson disease: an analysis of individual and collective clinical balance test in interpretation. Phys Ther. 2008;88:323-332.

(2) Fletcher RH, Fletcher SW, Wagner EH. Clinical Epidemiology: The Essentials. Philadelphia, Pa: Lippincott Williams & Wilkins; 1996.

(3) Lim LI, van Wegen EE, de Goede CJ, et al. Measuring gait and gait-related activities in Parkinson's patients own home environment: a reliability, responsiveness and feasibility study. Parkinsonism Relat Disord. 2005;11:19-24.

(4) Behrman AL, Light KE, Flynn SM, Thigpen MT. Is the functional reach test useful for identifying falls risk among individuals with Parkinson's disease? Arch Phys Meal Rehabil. 2002;83:538-542.

(5) Jacobs JV, Horak FB, Tran VK, Nutt JG. Multiple balance tests improve the assessment of postural stability in subjects with Parkinson's disease. J Neurol Neurosurg Psychiatry. 2006;77:322-326.

(6) Pickering RM, Grimbergen YA, Rigney U, et al. A meta-analysis of six prospective studies of falling in Parkinson's disease. Mov Disord. 2007;22:1892-1900.

[DOI: 10.2522/ptj.2008.88.5.679.1]

Author Response

We appreciate the thoughtful comments of Dr Norton in her reading of our recent article and welcome the opportunity to respond. During the evolution of this research and writing of this manuscript, our research group had many conversations regarding the appropriate terminology to describe the examination of the potential for falls in Parkinson disease (PD). Some of Norton's comments regarding the terminology echoed some of our own conversations. Rather than euphemistically use the terms "identification" or "imbalance," we consciously chose the terms "diagnosis" and "fall risk" in an effort to directly address the problem that we hope can be treated. In response, we wish to acknowledge Dr Norton's concerns but not debate whether "diagnosis" or "fall risk" were appropriate terms, but rather to clarify critical elements for optimal clinical decision making in the management of people with PD and our research agenda toward this end.

When physical therapists examine a person with a progressive neurologic disease such as PD, their mode of practice should encompass traditional tertiary preventive care of the current problems (eg, treating bradykinesia during gait, addressing bed mobility limitations). (1) In addition, optimal care should encompass secondary prevention; that is, awareness and treatment of complications of the disease process that are likely to occur in the future (eg, falls). (2,3)

As with many clinical decisions, in the context of PD, diagnosis or identification of a movement problem amenable to treatment is an imprecise endeavor. In order to provide the appropriate secondary preventive care, physical therapists must have accurate clinical measures to rule in or rule out target conditions that may respond to preventive or risk reduction treatments. Toward this end, our study sought to advocate for critical analysis of clinical balance test choice and interpretation rather than the blind acceptance of an individual test or cutoff score.

Above all concerns regarding terminology, the clinical relevance of being able to accurately apply a label to a patient that directs treatment (4) cannot be understated. Without question, further work remains. Prospective confirmation of the accuracy of these tests is needed, as are examinations of the efficacy of fall prevention and fall-risk reduction programs for persons with PD.

Leland E Dibble, K Bo Foreman, D James Ballard, Jesse Christensen

LE Dibble, PT, PhD, ATC, is Associate Professor (Clinical) at the University of Utah, Department of Physical Therapy, Salt Lake City, Utah.

This letter was posted as a Rapid Response on March 28, 2008, at www.ptjournal.org.

References

(1) Morris ME. Movement disorders in people with Parkinson disease: a model for physical therapy. Phys Ther. 2000;80:578-597.

(2) Bloem BR, Steijns JA, Smits-Engelsman BC. An update on falls. Curt Opin Neurol. 2003;16:15-26.

(3) Keus SH, Bloem BR, Hendriks EJ, et al. Practice Recommendations Development Group. Evidence-based analysis of physical therapy in Parkinson's disease with recommendations for practice and research. Mov Disord. 2007;22:451-460.

(4) Guide to Physical Therapist Practice. 2nd ed. Alexandria, Va: American Physical Therapy Association; 2003:32-38, 307.

[DOI: 10.2522/ptj.2008.88.5.679.2]