Background: Patient-reported physical function is a major component of disability determinations and an important contributor to health-related quality of life. Prior studies of coronary disability have shown a surprisingly poor correlation between real-life activity profile and exercise capacity measured on the treadmill. The goal of the current investigation was to evaluate the relative importance of medical factors, sex, fitness-related measures, and psychologic factors as determinants of patient-reported physical function score in older persons with established coronary heart disease (CHD).
Methods: Determinants of disability were studied in 51 community-dwelling patients >65 years old (71 +/- 5 years, range 65-83 years) with established chronic CHD. Patient-reported physical function score (scaled 0-100) was measured by the Medical Outcomes Study Short Form physical function section. Independent variables included clinical and demographic data, treadmill testing, rest and exercise echocardiography, measures of body composition, strength, aerobic fitness, and a depression score.
Results: Patients with a diagnosis of myocardial infarction had a lower physical function score than did patients with other CHD diagnoses (68 +/- 19 vs 82 +/- 22, P <.05). Univariate predictors of patient-reported physical function score included peak aerobic capacity (R = 0.62), treadmill test duration (R = 0.61), depression score (R = -0.60), handgrip strength (R = 0.42), and comorbidity score (R = -0.39). Peak aerobic capacity (R2 = 0.38) and depression score (cumulative R2 = 0.60) were the best independent predictors of physical function. Women had lower physical function scores than men (64 +/- 22 vs 78 +/- 20, P <.05) despite a similar age, diagnostic distribution, depression score, and comorbidity score. Resting left ventricular ejection fraction was not a predictor of physical function score.
Conclusions: Peak aerobic capacity and depression score were the best independent predictors of patient-reported physical function score in older coronary patients. These data focus on the potential for exercise training and treatment of mental depression to prevent and treat coronary disability in older coronary patients.