Concordance of Four Methods of Disability Assessment Using Performance in the Home as the Criterion Method JOAN C. ROGERS, 1 MARGO B. HOLM, 1 SCOTT BEACH, 1 RICHARD SCHULZ, 1 JOSEPH CIPRIANI, 2 ANDREA FOX, 3 AND TERENCE W. STARZ 1 Objective. To determine the concordance of 4 methods of disability assessment with the criterion method. Performance testing in the home was selected as the criterion. Methods. The task performance of 57 community-dwelling older women (>70 years) with knee osteoarthritis was examined through self report, proxy report, clinical judgment based on impairment measures, performance testing in an occupational therapy clinic, and performance testing in participants’ homes. The 26 tasks represented 4 domains of daily living activities: 5 functional mobility, 3 personal care, 14 cognitively oriented instrumental activities of daily living (IADL), and 4 physically oriented IADL. Results. In general, self reports and proxy reports had the highest concordance with in-home performance test results. Nonetheless, even for these methods, depending on task domain, the rate of discordance ranged from 31% to 54%, being least in personal care and greatest in the physically oriented IADL. Conclusion. Disability estimates based on self reports, proxy reports, clinical judgments, and hospital performance-based assessments are not interchangeable with in-home task performance. KEY WORDS. Functional assessment; Disability evaluation; ADL/IADL; Measurement. INTRODUCTION Assessing functional status is an integral component of arthritis care. The cumulative effects of disease-associated and age-related impairments are manifested in daily life. The capacity to perform basic activities of daily living (BADL), such as dressing and bathing, and instrumental activities of daily living (IADL), such as shopping for food and managing finances, is a salient marker of overall health, a critical determinant of the ability to live indepen- dently, and a major indicator of the help needed when functional status is impaired. The American College of Physicians (1), Royal College of Physicians of London (2), and the World Health Organization (3) all have endorsed the inclusion of functional assessment in effective patient management. Despite the importance of assessing function in BADL and IADL in the care of patients with arthritis, little is known about the relative concordance of the various meth- ods used to obtain this information. Self report question- naires, such as the Western Ontario and McMaster Univer- sities Osteoarthritis Index (4), the Health Assessment Questionnaire (5), and the Arthritis Impact Measurement Scales (6), support a client-centered, subjective approach. In contrast, the Functional Independence Measure (7) and the Klein-Bell Activities of Daily Living Scale (8), where patients are actually observed carrying out their daily ac- tivities in either a simulated (e.g., occupational therapy clinic) or naturalistic (e.g., home or nursing home) setting, reflect an objective, performance-based measurement ap- proach. Compared with objective methods, subjective methods are easy to learn, require less skill to administer, are less time consuming to administer, and are less costly. If the yield from subjective and objective methods is com- parable, disability would be defined similarly by either option, and subjective methods would be preferred be- cause of their cost effectiveness. Supported by a grant from the National Institute on Aging and the Agency for Healthcare Policy and Quality (AG08947). 1 Joan C. Rogers, PhD, Margo B. Holm, PhD, Scott Beach, PhD, Richard Schulz, PhD, Terence W. Starz, MD: Univer- sity of Pittsburgh, Pittsburgh, Pennsylvania; 2 Joseph Cipri- ani, EdD: College Misericordia, Dallas, Pennsylvania; 3 An- drea Fox, MD: University of Pittsburgh and VA Pittsburgh GRECC, Pittsburgh, Pennsylvania. Address correspondence to Dr. Joan C. Rogers, 5017 Forbes Tower, School of Health and Rehabilitation Sci- ences, Pittsburgh, PA 15260. E-mail: jcr@pitt.edu. Submitted for publication April 14, 2002; accepted in revised form October 21, 2002. Arthritis & Rheumatism (Arthritis Care & Research) Vol. 49, No. 5, October 15, 2003, pp 640 – 647 DOI 10.1002/art.11379 © 2003, American College of Rheumatology ORIGINAL ARTICLE 640