Comparative validity of seven scoring systems for the instrumental activities of daily living scale in rural elders

Abstract

Lawton and Brody's eight-item Instrumental Activities of Daily Living (IADL) scale is used often with elderly patients but scored in several different ways. We scored the IADL with seven popular procedures ranging from relatively simple to complex (Guttman scores, summed and Rasch scores from dichotomous, trichotomous, and polytomous items) in a sample of rural elders (N = 231). We compared the IADL scales’ prediction of concurrent cognitive functioning, depressive symptoms, psychosocial functioning, and health care use (medications, outpatient visits, inpatient days). Validity coefficients ranged from small to large among outcome variables but were highly consistent across IADL scoring procedures. Consequently, researchers and clinicians may prefer to use simpler IADL scoring procedures with this population.

Acknowledgements

This research was supported in part by grants D04-RH-00242 from the Health Resources and Services Administration and 5-H79-SM-54852 from the Substance Abuse and Mental Health Services Administration. We are grateful to our colleagues for their assistance with this project: Marca Cenatiempo, Doris Fountain, Andrew Lovy, Robin Lukefahr, Robert McClain, and Brenda Sidwell provided clinical support; Cheylynne Bosley, Toviah Cain, and Theresa Taylor provided administrative and research support.