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Effects of age on activity patterns after coronary artery bypass surgery
1College of Nursing, Rutgers, The State University of New Jersey, Newark 08102, USA.
Objective:
To examine the effect of age on activity patterns, including circadian rhythms and levels, after coronary artery bypass surgery (CABS).
Design:
Repeated measures, correlational.
Setting:
Northeastern university-affiliated tertiary coronary care center.
Subjects:
Eight middle-aged (mean age = 57 years) and 14 older (mean age = 72 years) adults who had undergone first, isolated CABS.
Outcome Measures:
Wrist actigraph measures of levels (daytime activity) and circadian patterns of activity (acrophase, amplitude, percent rhythm, mesor), self-reported postoperative clinical activity milestones, and Sickness Impact Profile subscales of ambulation dysfunction and sleep-rest.
Intervention:
Measurement of activity over postoperative days 2 through 5, including wrist actigraphy, Sickness Impact Profile ambulation and sleep-rest subscales, and daily clinical activity milestones.
Results:
Repeated measures ANOVA was used in the data analysis. Statistically significant increases were found in percent rhythm (P <.001), amplitude (P <.001), activity level (P <.001), and clinical activity milestones (P <.001) over postoperative days 2 through 5. Significant effects of age were found on amplitude (P =.02) and percent rhythm (P =.008). Significant age-by-time effects were found for circadian amplitude (P =.03) and percent rhythm (P =.02). There was a nonstatistically significant (P =.07) age by time interaction effect on daytime activity. Trends in amplitude, percent rhythm, and daytime activity indicated that these activity parameters increased more slowly in older adults, compared with middle-aged adults, after initially similar levels on postoperative days 2 and 3.
Conclusion:
Both middle-aged and older adults increase daily activity and the strength of circadian activity pattern over days 2 through 5. However, these variables increase more rapidly in middle-aged adults after essentially identical levels on postoperative days 2 and 3.