Relationships between symptoms, physical capacity and activity limitations in 1992 and 2002

Studies of health trends suggest that various components of health and disability follow different trends over time. This in turn suggests that the relations between different health outcomes may change. This study explores associations between three kinds of outcomes (symptoms, physical capacity, activity limitations) in order to evaluate whether relationships between them had changed over the past decade. Ordered logistic regressions evaluated the relationships between variables in two collapsed representative samples of the Swedish oldest old (77+) in 1992 and 2002, living at home and in institutions (n=1115, non-response 15%, proxy interviews 13%). Interviews included symptoms (fatigue, pain and dizziness), physical capacity (tests of lung function + physical performance, and mobility, i.e., walking, running, and climbing stairs) and activity limitations (IADL, ADL). Prevalence of symptoms and poor capacity was higher in 2002 than in 1992, whereas the prevalence of activity limitations did not change. All symptoms were related to physical capacity. Fatigue and pain were related to activity limitations with adjustments for physical capacity, as well as independently. All capacity measures had independent relationships with activity limitations. The relationship of fatigue with ADL was weaker in 2002 than in 1992. Adjusted for performance and lung function, the relationship of mobility with ADL was also weaker. Otherwise, relationships were not significantly different (p>0.05). Among old people, symptoms are closely associated with activity limitations. Identifying the role of symptoms may enhance development of early interventions. The weakened relationship between ADL and functional limitations indicate that they follow different trends.