G Warner, Center for Health Quality, Outcomes and Economic Research (CHQOER); E Borawski, Case Western Reserve University; E Kahana, Case Western Reserve University; K Stange, Case Western Reserve University

Objectives: To demonstrate the importance of measuring fatigue/energy levels in an elderly population, using the SF-36 Vitality sub-scale, to indicate present and future health status. Due to the high level of comorbidities and weakened health status, lack of vitality (or fatigue) is a common presenting symptom within the elderly. This study validates the utility of the Vitality sub-scale by describing the cross-sectional presentation and prospective associations of fatigue with present health status measures and future activity limitations.

Methods: Two years of a longitudinal study (The Elderly Care Research Center Florida Retirement Study) during which the SF-36 was administered, were used to describe both the psychosocial and physical health attributes of fatigue/energy. The elderly population (mean age=81) was randomly sampled from three Florida retirement communities. Face-to-face interviews and performance based health measurements were done annually, in years 4 (N=636) and 6 (N=462) the participants were mailed the SF-36. The SF-36 includes a Vitality sub-scale that measures energy and fatigue with 4 items. The population was primarily white, 66 percent female and 33 percent reported fair or poor self assessed health. Among the available measures were the CES-D scale, the PANAS positive and negative affect scale, number of medications, number of comorbidities, self assessed health scale, the Rose Blackburn Dyspnea scale and the Tinetti Mobility Scale. The Activities of Daily Living and Instrumental Activities of Daily Living (ADL/IADL) scale was used as the primary outcome to assess activity limitations.

Results: In cross sectional analysis the summed Vitality sub-scale showed strong associations with both physical and psychosocial measurements. The strongest associations (over .40 and p<.001) were for depression (0.48), the PANAS positive (-0.45), the number of comorbidities (0.45), trouble with ADL/IADLs (0.51) self assessed health (-0.65) and the Rose Blackburn Dyspnea scale (0.41). Prospectively, the vitality score at time 4 had a stronger association with ADL/IADL status at time 6 (0.45) than other indicators measured at time 4, only mobility status (-0.54) and ADL/IADL status (0.67) were stronger. When the IADL/ADL scale was dichotomized (none versus any) the vitality score remained statistically significant in multivariable logistic regression after controlling for gender, self assessed health, depression, mobility and ADL/IADL status Odds Ratio=1.2 (1.1-1.3).

Conclusions: The Vitality sub-scale is a strong concurrent indicator of mental and physical health status. It also is an important predictor of the future ability to perform social tasks as measured by the ADL/IADL scale.

Impact: The Vitality sub-scale was shown to be a significant predictor of future activity restrictions in the elderly. The Veteran Administration (VA) patient population has a large percentage of elderly people with high comorbidity levels, which encompass both physical and mental health impairments. The "1999 Large Health Survey of Veteran Enrollees" will supply important information necessary to compare the utility of this sub-scale across a number of different medical conditions within the elderly.