Quality of Life Research

, Volume 22, Issue 7, pp 1621–1632 | Cite as

Functional status, life-space mobility, and quality of life: a longitudinal mediation analysis

  • John P. Bentley
  • Cynthia J. Brown
  • Gerald McGwinJr.
  • Patricia Sawyer
  • Richard M. Allman
  • David L. Roth
Article

Abstract

Purpose

Using the Wilson–Cleary model of patient outcomes as a conceptual framework, the impact of functional status on health-related quality of life (HRQoL) among older adults was examined, including tests of the mediation provided by life-space mobility.

Methods

Participants were enrollees in a population-based, longitudinal study of mobility among community-dwelling older adults. Data from four waves of the study equally spaced approximately 18 months apart (baseline, 18, 36, and 54 months) were used for participants who survived at least 1 year beyond the 54-month assessment (n = 677). Autoregressive mediation models using longitudinal data and cross-sectional mediation models using baseline data were evaluated and compared using structural equation modeling.

Results

The longitudinal autoregressive models supported the mediating role of life-space mobility and suggested that this effect is larger for the mental component summary score than the physical component summary score of the SF-12. Evidence for a reciprocal relationship over time between functional status, measured by ADL difficulty, and life-space mobility was suggested by modification indices; these model elaborations did not alter the substantive meaning of the mediation effects. Mediated effect estimates from longitudinal autoregressive models were generally larger than those from cross-sectional models, suggesting that mediating relationships would have been missed or were potentially underestimated in cross-sectional models.

Conclusions

These results support a mediating role for life-space mobility in the relationship between functional status and HRQoL. Functional status limitations might cause diminished HRQoL in part by limiting mobility. Mobility limitations may precede functional status limitations in addition to being a consequence thereof.

Keywords

Wilson–Cleary model Activities of daily living Mobility SF-12 Longitudinal mediation Autoregressive mediation modeling 

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Copyright information

© Springer Science+Business Media Dordrecht 2012

Authors and Affiliations

  • John P. Bentley
    • 1
  • Cynthia J. Brown
    • 2
    • 3
  • Gerald McGwinJr.
    • 4
  • Patricia Sawyer
    • 3
  • Richard M. Allman
    • 5
  • David L. Roth
    • 6
  1. 1.School of PharmacyUniversity of Mississippi UniversityUSA
  2. 2.Birmingham VA Medical CenterUniversity of Alabama at BirminghamBirminghamUSA
  3. 3.Division of Gerontology, Geriatrics, and Palliative CareUniversity of Alabama at BirminghamBirminghamUSA
  4. 4.Department of EpidemiologyUniversity of Alabama at BirminghamBirminghamUSA
  5. 5.Atlanta VA Geriatric Research, Education, and Clinical Center, Center for Aging, and Division of Gerontology, Geriatrics, and Palliative CareUniversity of Alabama at BirminghamBirminghamUSA
  6. 6.Center on Aging and HealthJohns Hopkins UniversityBaltimoreUSA

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