Beyond Dueling Models Commentary Responding to: Guralnik JM, Ferrucci L. The Challenge of Understanding the Disablement Process in Older Persons and Freedman V. Adopting the ICF Language for Studying Late-life Disability: A Field of Dreams?

I’D like to begin by thanking Drs Guralnik, Ferrucci, and Freedman for their thoughtful reflections in response to my guest editorial, Toward a Common Language of Disablement (1). These efforts will initiate an important dialogue within gerontology that I believe will be very useful in furthering the study of late-life disability. The commentators and I agree that there is merit in having an internationally agreed-upon language and framework for the study of late-life disability. Where opinions diverge is over whether or not the ICF in its current form is worthy of embrace by the U.S. gerontological community (2). Let me remind readers of the journal of some recent history with respect to disability frameworks. For almost 30 years, two prominent disability frameworks were in widespread use around the globe (3). One is the International Classification of Impairment, Disability, and Handicap (ICIDH) of the World Health Organization (WHO) used widely outside the United States (4). A second framework is Nagi’s Disablement Model that is used widely within the United States (5). There are several variations on these two major models (6,7). Although the ICIDH and Nagi formulations include the concept of disability, unfortunately they do not define them the same way. In Nagi’s model, the concept of disability is defined as limitation in performing socially defined roles and tasks expected of an individual within a sociocultural and physical environment; disability, as defined by Nagi, represented the expression of a physical or a mental limitation in a social context. In contrast, the ICIDH defined disability as any restriction of lack (resulting from an impairment) of ability to perform an activity in the manner or within the range considered normal for a human being. In the past, if a researcher wished to publish in a journal that used the ICIDH, one had to define disability one way, but if you were publishing within a U.S. journal that used Nagi’s language, one had to define it another way. When researchers read and/or reviewed the worldwide disability literature one could not always tell which disability concept and definition was being used. For years, dueling disability models created a considerable barrier to scientific discourse as well as communication across disciplines and, in my view, impeded the advance of knowledge in disability research. After almost three decades, it seems time to acknowledge that using different disability models and definitions has not facilitated advances in the field of disability research. I think we need to try another approach. I agree with the commentators that the ICF contains important shortcomings, problems that I have written about, and am trying to address in my own research (8–10). As Chair of the Institute of Medicine (IOM) Committee that published the 2007 report, The Future of Disability in America, I recall the vigorous debates the committee had over whether it should create its own disability framework and definitions as past IOM disability committees have done. The Committee struggled over whether to endorse the ICF and call for efforts to refine and improve the ICF. I remain convinced that the IOM Committee achieved the right balance when we reached the following unanimous decision: The committee recommends that the National Center for Health Statistics, the US Census Bureau, the Bureau of Labor Statistics, and other relevant government units involved in disability monitoring should adopt the International Classification of Functioning, Health, and Disability (ICF) as their conceptual framework and should actively promote continued refinements to improve the framework's scope and utility for disability monitoring and research. … Achieving universally accepted and understood terminology, language, and concepts with which to describe and discuss the concept of disability will remove one barrier to progress in disability research and public policy. This will not happen immediately, but, rather, will involve a long term process of further movement toward the adoption and application of the ICF conceptual framework combined with continued efforts to refine and improve that framework and to develop tools and methods for applying it. (11) The ICF is not in its final form. Like the WHO’s International Classification of Diseases, the ICF is intended to undergo future revision (12,13). One challenge is to conduct research on the ICF that can be used to influence those future revisions. Work such as that being done by the National Health and Aging Trends Study that Dr Freedman writes about is instrumental in tackling several key operational concerns raised by Drs Guralnik and Ferrucci on how best to measure ICF concepts. Much work remains to be done to improve the ICF framework. Whether one is focused on early-onset, middle-age, or late-life disability, achieving agreement on disability concepts and definitions is a critical first step for describing and measuring different aspects of disability and understanding its epidemiology, prevention, and treatment. Using a common disability language should increase the comparability of disability research findings and make our research more useful to decision makers. The ICF is an important first step toward achieving this goal and for this reason should be embraced, used, and improved by the gerontological community.