title: Moderators, mediators, and bidirectional relationships in the International Classification of Functioning, Disability and Health (ICF) framework: An empirical investigation using a longitudinal design and Structural Equation Modeling (SEM).
abstract: The International Classification of Functioning, Disability and Health (ICF) published in 2001 describes the consequences of health conditions with three components of impairments in body structures or functions, activity limitations and participation restrictions. Two of the new features of the conceptual model were the possibility of feedback effects between each ICF component and the introduction of contextual factors conceptualized as moderators of the relationship between the components. The aim of this longitudinal study is to provide empirical evidence of these two kinds of effect. Structural equation modeling was used to analyze data from a French population-based cohort of 548 patients with knee osteoarthritis recruited between April 2007 and March 2009 and followed for three years. Indicators of the body structure and function, activity and participation components of the ICF were derived from self-administered standardized instruments. The measurement model revealed four separate factors for body structures impairments, body functions impairments, activity limitations and participation restrictions. The classic sequence from body impairments to participation restrictions through activity limitations was found at each assessment time. Longitudinal study of the ICF component relationships showed a feedback pathway indicating that the level of participation restrictions at baseline was predictive of activity limitations three years later. Finally, the moderating role of personal (age, sex, mental health, etc.) and environmental factors (family relationships, mobility device use, etc.) was investigated. Three contextual factors (sex, family relationships and walking stick use) were found to be moderators for the relationship between the body impairments and the activity limitations components. Mental health was found to be a mediating factor of the effect of activity limitations on participation restrictions.
authors.affiliation: AP-HP, Hôtel-Dieu Hospital, Biostatistics and Epidemiology Department, 1 place du parvis Notre-Dame, 75181 Paris cedex 04, France; Inserm, U1178, Mental Health and Public Health, Université Paris-Sud and Université Paris-Descartes, Maison de Solenn, 97 boulevard du Port-Royal, 75014 Paris, France; Research Unit on Children's Psychosocial Maladjustment, University of Montreal, 3050 Édouard Montpetit, H3T 1J7, Montreal, Quebec, Canada. Electronic address: alex.rouquette@gmail.com.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Rouquette
authors.affiliation: The Arthritis Community Research and Evaluation Unit, Division of Health Care and Outcomes Research, Toronto Western Research Institute, Toronto, Ontario, Canada; Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada; Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada. Electronic address: e.badley@utoronto.ca.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Badley
authors.affiliation: Inserm, U1178, Mental Health and Public Health, Université Paris-Sud and Université Paris-Descartes, Maison de Solenn, 97 boulevard du Port-Royal, 75014 Paris, France; AP-HP, Paul Brousse Hospital, Public Health Department, Villejuif, France. Electronic address: bruno.falissard@gmail.com.
authors.forename: Bruno
authors.initials: B
authors.lastname: Falissard
authors.affiliation: AP-HP, Hôtel-Dieu Hospital, Biostatistics and Epidemiology Department, 1 place du parvis Notre-Dame, 75181 Paris cedex 04, France. Electronic address: timodub@gmail.com.
authors.forename: Timothée
authors.initials: T
authors.lastname: Dub
authors.affiliation: Research Unit APEMAC, EA 4360, Nancy-Université, Université Paris-Descartes, Université Metz Paul Verlaine, Ecole de Santé Publique, Faculté de Médecine, Université de Lorraine, 9 avenue de la Forêt de Haye, BP 184, 54505 Vandoeuvre les Nancy cedex, Paris, France; Université Paris Diderot, Département d'Histoire et de Philosophie des Sciences, UFR Sciences du vivant, 4 rue Elsa Morante, 75205 Paris cedex 13, France. Electronic address: alain.leplege@univ-paris-diderot.fr.
authors.forename: Alain
authors.initials: A
authors.lastname: Leplege
authors.affiliation: AP-HP, Hôtel-Dieu Hospital, Biostatistics and Epidemiology Department, 1 place du parvis Notre-Dame, 75181 Paris cedex 04, France; Research Unit APEMAC, EA 4360, Nancy-Université, Université Paris-Descartes, Université Metz Paul Verlaine, Ecole de Santé Publique, Faculté de Médecine, Université de Lorraine, 9 avenue de la Forêt de Haye, BP 184, 54505 Vandoeuvre les Nancy cedex, Paris, France. Electronic address: joel.coste@htd.aphp.fr.
authors.forename: Joël
authors.initials: J
authors.lastname: Coste
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D004185:Disability Evaluation; D006233:Persons with Disabilities / Q000145:classification / Q000534:rehabilitation* / Q000706:statistics & numerical data; D005246:Feedback; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D038801:International Classification of Diseases / Q000706:statistics & numerical data; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D020370:Osteoarthritis, Knee / Q000503:physiopathology; D011795:Surveys and Questionnaires
keywords: Effect modifier; Epidemiologic; Feedback effects; International Classification of Functioning Disability and Health; Knee; Longitudinal study; Osteoarthritis; Structural Equation Modeling