Physiologic, psychologic, and health predictors of 6-minute walk performance in older people

Abstract

Objective: To determine the extent to which physiologic, psychologic, and health-related factors predict 6-minute walk distance (6MWD) in older people.

Design: Cross-sectional study.

Setting: Retirement villages.

Participants: A total of 515 people between the ages of 62 and 95 years (mean +/- standard deviation, 79.5+/-6.4y) residing in retirement villages in Australia.

Interventions: Not applicable.

Main outcome measures: Quantitative tests of vision, strength, peripheral sensation, reaction time, and balance and short Mini-Mental State Examination, Geriatric Depression Scale, Positive and Negative Affect Schedule (PANAS), Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), and 6MWD.

Results: All physiologic, psychologic, and health scores were significantly associated with 6MWD. Multiple regression analysis revealed that 10 factors (visual contrast sensitivity, lower-limb strength, simple reaction time, postural sway, maximal balance range, PANAS positive scale score, SF-36 pain score, number of medications used, SF-36 general health subscale score, age) were significant and independent predictors of 6MWD performance. Of these measures, strength, maximal balance range, medication use, and age explained the largest proportions of the variance in 6MWD. The final regression model explained over half (52.5%) of the variance in 6MWD (multiple r=.72).

Conclusions: In older people, 6MWD depends on multiple physiologic, psychologic, and health factors. Thus, 6MWD appears to provide a measure of overall mobility and physical functioning in this population group rather than a specific measure of cardiovascular fitness.