Variability in measuring (instrumental) activities of daily living functioning and functional decline in hospitalized older medical patients: a systematic review Bianca M. Buurman a, * , Barbara C. van Munster a,b , Johanna C. Korevaar b , Rob J. de Haan c , Sophia E. de Rooij a a Department of Internal Medicine and Geriatrics, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands b Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Centre, University of Amsterdam, The Netherlands c Clinical Research Unit, Academic Medical Centre, University of Amsterdam, The Netherlands Accepted 23 July 2010 Abstract Objective: To study instruments used and definitions applied in order to measure (instrumental) activities of daily living (I [ADL]) functioning and functional decline in hospitalized older medical patients. Study Design: We systematically searched Medline, Embase, and the Cochrane Database of Systematic Reviews from 1990 to January 2010. Articles were included if they (1) focused on acute hospitalization for medical illness in older patients; (2) described the instrument used to measure functioning; and (3) outlined the clinical definition of functional decline. Two reviewers independently extracted data. Results: In total, 28 studies were included in this review. Five different instruments were used to measure functioning: the Katz ADL index, the IADL scale of Lawton and Brody, the Barthel index, Functional Independence Measure, and Care Needs Assessment. Item con- tent and scoring between and within the instruments varied widely. The minimal amount for decline, as defined by the authors, referred to a decrease in functioning between 2.4% and 20.0%. Conclusion: This review shows there is a large variability in measuring (I)ADL functioning of older hospitalized patients and a large range of clinical definitions of functional decline. These conceptual and clinimetric barriers hamper the interpretation and comparison of functional outcome data of epidemiological and clinical studies. Ó 2011 Elsevier Inc. All rights reserved. Keywords: Functional decline; Systematic review; Measurement; Older patient; Hospitalized; Activities of daily living; Instrumental activities of daily living 1. Introduction Acute hospitalization in older patients is not without risk because these patients are more prone to adverse events as compared with younger patients [1,2]. An important nega- tive health outcome in this population is functional decline. Functional decline can lead to (permanent) disability and may lead to a prolonged hospital stay, institutionalization, and even death [3e5]. Medical patients are a vulnerable group for functional decline. They often present to the hospital with deterioration in functioning, as a result of an acute exacerbation of chronic multimorbid conditions. Not only in daily practice but also in clinical research, functional decline has become a key outcome after hospi- talization in older patients, supported by the working group on functional outcome measures in clinical trails [6]. Activ- ities of daily living (ADL) and instrumental activities of daily living (IADL) are an essential part of patients’ func- tional status, as is also demonstrated in the International Classification of Functioning from the World Health Organization (WHO) [7]. ADL and IADL functioning are located centrally in this model and affected by disease, impairment, personal factors, and environmental factors. Many studies focus on functional decline after acute hospitalization in older patients. A review of McCusker et al. [8] already pointed out that there is a large variability in studies on functional decline in terms of study design, analysis, and time of follow-up. In this article, however, relatively little attention has been given to the measurement itself and the applied definitions of functional decline. Uni- formity in measuring functional decline is essential for appraising study results and conducting meta-analyses. To * Corresponding author. Department of Internal Medicine, Geriatric section, Room F4-108, Academic Medical Centre, PO Box 22660, 1100 DD, Amsterdam, The Netherlands. Tel.: þ31-205665991; fax: þ31-205669325. E-mail address: B.m.vanes@amc.uva.nl (B.M. Buurman). 0895-4356/$ - see front matter Ó 2011 Elsevier Inc. All rights reserved. doi: 10.1016/j.jclinepi.2010.07.005 Journal of Clinical Epidemiology 64 (2011) 619e627