AGING WITH LONG-TERM PHYSICAL DISABILTY: THE ROLE OF SECONDARY CONDITIONS Heather J. Moulton Submitted in partial fulfillment of the requirements for the degree of Doctor of Public Health in the Mailman School of Public Health COLUMBIA UNIVERSITY 2014 © 2014 Heather J. Moulton All rights reserved ABSTRACT Aging with Long-Term Physical Disability: The Role of Secondary Conditions Heather J. Moulton Objectives: The purpose of this study is to advance the understanding of secondary conditions experienced by persons aging with the long-term disabilities of polio and rheumatoid arthritis and the consequences of these declines in health and function on disability bed days. Additionally, it explores the effects of the timing and severity of onset of disability characteristics on the frequency and consequences of secondary conditions. A life course conceptual framework with the Institute of Medicine’s model of disablement is used to frame and anchor disability and life events. Methods: In-depth structured in-home interviews were conducted on 216 individuals with polio and 186 individuals with rheumatoid arthritis. They consisted of objective and subjective self-reports of current status and prior condition. The survey was a regional cross- sectional, group comparison design with a cross-sequential sampling and data analytic framework. Scale development for data reduction was utilized to obtain parsimonious measures for the models. Linear regression was then performed to test the models for three outcome variables (number of chronic secondary conditions, increases in functional limitations and number of disability bed days in six months) in a theorized order for the polio and RA samples individually. Results: There was partial support for within-sample hypotheses for both polio and rheumatoid arthritis regarding interrelationships and disability bed days in past six months. No significant differences were found across subsamples for the effects of timing and severity of onset of disability characteristics, predicting chronic secondary conditions, predicting increase in functional limitations, and the number of disability bed days in six months. Similarities were found between the two samples when examining subgroup predictors on the three outcomes above. Chronic secondary conditions predicted (p<.05 for both subsamples) increase in functional limitations and increase in mobility was a significant predictor (p<.001 for both subsamples) of increase in functional limitations. Discussion: There were limited findings for these data. Judgment must be withheld with respect to the hypotheses. The analyses did not yield enough predictive strength to make comparisons possible across subsamples. Likewise, in examining similarities, only general, descriptive statements could be made. The subjective nature of disability is an immense challenge in cross disability research for comparability within disabilities and across disabilities. TABLE OF CONTENTS LIST OF TABLES ...........................................................................................................................v LIST OF FIGURES ...................................................................................................................... vii ACKNOWLEDGEMENTS ......................................................................................................... viii DEDICATION .................................................................................................................................x I. INTRODUCTION ................................................................................................................1 A. Statement of the Problem .........................................................................................5 B. Study Goals ..............................................................................................................6 II. LITERATURE REVIEW .....................................................................................................8 A. Disablement .............................................................................................................8 1. The Nagi Model & The Institute of Medicine .........................................................8 2. International Classification of Impairments, Disease, and Handicap ......................9 3. The Disablement Process .......................................................................................10 4. The International Classification of Function, Disease, and Health .......................10 B. Aging with Disability .............................................................................................12 C. Secondary Conditions ............................................................................................13 1. Symptoms ..........................................................................................................15 2. Chronic Conditions ................................................................................................16 3. Functional Limitations and Functional Disability .................................................21 D. Public Health’s Role in Disability .........................................................................23 E. Disability Groups: Polio and Rheumatoid Arthritis ...............................................25 1. Poliomyelitis and Post-Polio Syndrome ................................................................26 i 2. Rheumatoid Arthritis .............................................................................................31 III. CONCEPTUAL FRAMEWORK AND HYPOTHESES ...................................................37 A. Life Course, Disability Trajectory and Disablement .............................................37 B. Models....................................................................................................................42 C. Conceptual Models and Hypotheses ......................................................................46 1. Polio Hypotheses ...................................................................................................46 a. Interrelationships Among Components ........................................................ 46 b. Unique Disability Characteristics ................................................................. 47 c. Disability Bed Days ...................................................................................... 47 2. Rheumatoid Arthritis Hypotheses ..........................................................................48 a. Interrelationships Among Components ........................................................ 48 b. Unique Disability Characteristics ................................................................. 48 c. Disability Bed Days ...................................................................................... 49 3. Comparison of Disability Group Differences........................................................49 IV. METHODS .........................................................................................................................51 A. Study Design For Secondary Data .........................................................................51 1. Instrumentation ......................................................................................................51 2. Study Sample .........................................................................................................55 3. Sample Demographics ...........................................................................................58 4. Data Collection ......................................................................................................60 B. Model Development for Present Analyses ............................................................60 1. Scale Development ................................................................................................60 2. Predictive Model ....................................................................................................63 ii 3. Final Analysis ........................................................................................................63 V. RESULTS: SCALE DEVELOPMENT .............................................................................65 A. Increases (Change) in Symptoms ...........................................................................65 B. Increases (Change) in Functional Limitations .......................................................66 1. Basic Activities of Daily Living ............................................................................66 2. Instrumental Activities of Daily Living .................................................................68 3. Mobility ..........................................................................................................69 C. Number of Chronic Secondary Health Conditions ................................................72 D. Changes in Model Based on Scale Development Results .....................................73 1. Increase in Functional Limitations .........................................................................73 2. Chronic Secondary Conditions ..............................................................................74 3. Summary ..........................................................................................................75 VI. RESULTS: MODEL TESTING ........................................................................................76 A. Interrelationships Among Components .................................................................77