Purpose: To assess the influence of age on the relationships between global measures of health and specific health dimensions.
Design: Cross-sectional cohort study.
Setting: University tertiary care hospital.
Patients: Patients older than 50 years admitted for major elective non-cardiac surgery.
Measurements: Consenting patients underwent preoperative evaluations including a medical history, physical examination, and administration of health status assessment instruments. Global health status was measured with the Medical Outcomes Study Short Form (SF-36) and with a 0 to 100 verbal measure of global health. Specific health dimensions (physical function, role function, social function, mental health, energy and fatigue, and pain) were measured using the SF-36. Subjects also completed a second validated measure of physical functioning, the Specific Activity Scale (SAS).
Results: Although patients aged > 70 years (n = 276) had poorer role function, energy, and fatigue scores and poorer physical function on both the SF-36 and SAS than younger patients (n = 469) (P < 0.05), they had similar overall health perception. In the entire population, global health status as measured with the SF-36 health perception scale had the greatest correlation with the energy and fatigue scale (r = .45), correlated moderately with mental health (r = .35), social function (r = .32), and physical function (r = .33), and correlated less well with the surgically remediable dimension of pain (r = .23). However, correlations of global health perception with pain and global health perception with role functioning were significantly (P < or = 0.05) lower in older patients when compared with subjects 70 years or younger (r = .13 vs .28 and r = .19 vs .33, respectively).
Conclusion: Despite poorer role function, poorer energy and fatigue scores, and poorer physical function, elderly persons have similar global health perception when compared with younger individuals. These data indicate that global health perception may be determined by different factors in the elderly or that the elderly have fundamentally different expectations of what their global health status should be. Our findings emphasize the importance of multidimensional scales when evaluating quality of life because, particularly in the elderly, the use of global measures alone may not reflect critically important dimension-specific impairments in health.