title: Impact of missing data mechanism on the estimate of change: a case study on cognitive function and polypharmacy among older persons.
abstract: Longitudinal studies typically suffer from incompleteness of data. Attrition is a major problem in studies of older persons since participants may die during the study or are too frail to participate in follow-up examinations. Attrition is typically related to an individual's health; therefore, ignoring it may lead to too optimistic inferences, for example, about cognitive decline or changes in polypharmacy. The objective of this study is to compare the estimates of level and slope of change in 1) cognitive function and 2) number of drugs in use between the assumptions of ignorable and non-ignorable missingness. This study demonstrates the usefulness of latent variable modeling framework. The results suggest that when the missing data mechanism is not known, it is preferable to conduct analyses both under ignorable and non-ignorable missing data assumptions.
authors: Kuopio Research Centre of Geriatric Care, University of Eastern Finland, Kuopio, Finland ; School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland.
authors: Piia
authors: P
authors: Lavikainen
authors: Department of Mathematics and Statistics, University of Jyväskylä, Jyväskylä, Finland.
authors: Esko
authors: E
authors: Leskinen
authors: Kuopio Research Centre of Geriatric Care, University of Eastern Finland, Kuopio, Finland ; School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland.
authors: Sirpa
authors: S
authors: Hartikainen
authors: Department of Social Research, University of Helsinki, Helsinki, Finland.
authors: Jyrki
authors: J
authors: Möttönen
authors: Department of Geriatrics, Institute of Public Health and Clinical Nutrition, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland.
authors: Raimo
authors: R
authors: Sulkava
authors: Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Turku, Finland.
authors: Maarit J
authors: MJ
authors: Korhonen
keywords: Mini-Mental State Examination; attrition; latent variable modeling; longitudinal; number of drugs; older persons