Association Between Social Support and Physical Activity In Patients With COPD

Chen Z, Fan VS, Nguyen H. Association Between Social Support and Physical Activity In Patients With COPD. Paper presented at: American Thoracic Society Annual International Conference; 2014 May 16; San Diego, CA.

Rationale: Little is known regarding the influence of cognitive functioning on functional status in patients with chronic obstructive pulmonary disease (COPD). The purpose of this analysis was to examine whether cognitive functioning differentially affects functional capacity as measured in the laboratory and free-living physical activity in stable COPD. Methods: Data for this cross-sectional analysis were obtained from CASCADE, an ongoing longitudinal observational study of depression in COPD. Participants completed the Trail Making Test B (Trails B), a common neuropsychological test requiring visual search, scanning, processing speed, mental flexibility, and executive control. Functional capacity was measured with a six minute walk test (6MWT) and free-living ambulatory physical activity was measured with a validated accelerometer (Stepwatch) over a 7 day period. Trails B data were analyzed in relation to established population norms (Tombaugh, 2003) and quartile categories, with longer time to test completion indicating worse cognitive function. Descriptive statistics and analyses of variance were used with Bonferroni correction for post hoc contrasts. Results: A total of 282 GOLD Stage II-IV COPD patients were included in the analysis with the following characteristics: mean age of 68 9; 20% females; mean FEV1% predicted of 45.0 16; median total step count/day of 5773; and mean 6MW distance of 1090 372 feet. Three-quarters (n = 212) of the sample performed below population norms on the Trails B test and this did not vary by GOLD stage (p = .20). There were no significant differences in either measure of functional status between participants below or above population norms (p > .05). However, longer Trails B times, when analyzed by quartile, were significantly associated with worse functional capacity (p value for trend 0.003) and free-living physical activity (p = .049). Patients with the worst cognitive function (quartile 4) covered 154, 190 and 209 fewer feet during the 6MWT compared to quartiles 3, 2, and 1 respectively, meeting nearly all conventional minimal clinically important difference standards. Physical activity was also significantly lower in the worst cognitive functioning group by 1521 steps/day compared to patients with the highest cognitive functioning. Conclusion: A high percentage of this cohort of patients with stable COPD was classified having below normal cognitive functioning; however this cut-off was not sensitive in detecting differences in functional status. Findings demonstrate that deficits in executive cognitive functioning, especially when severe, can be associated with reduced physical performance in COPD.