Validation of the ACT24 Physical Activity Instrument in Women Undergoing Chemotherapy

Background: While physical activity during chemotherapy is recognized as a vital component of overall health and well-being, there is a lack of ideal measures that can accurately and efficiently measure physical activity. The purposes of this study were to (1) validate the Activities Completed over Time in 24 Hours (ACT24) instrument and (2) evaluate participant use and acceptability of the ACT24 for women undergoing active chemotherapy for the treatment of breast cancer. Methods: Twenty-two women receiving chemotherapy wore an activPAL device for 7 days and completed 3 ACT24 previous day recalls. Criterion validity was assessed using correlation coefficients, paired t tests, and Bland–Altman plots from data collected on matched days for the ACT24 and activPAL. Outcomes of interest included MET-hrs/day, active time, and sedentary time. Acceptability was assessed using the System Usability Scale and Experience survey. Results: The correlations between the ACT24 and activPAL were significant for MET-hrs/day ( ρ = 0.80, P <.001), active time ( ρ = 0.70, P <.001), and sedentary time ( ρ = 0.67, P <.001); and there were no significant differences in measures obtained with the ACT24 and activPAL for all outcomes ( P ranged from 0.222 to 0.706). For usability, the ACT24 exceeded the mean cutoff score of usability on the System Usability Scale, indicating acceptable usability of the measure. Conclusion: The ACT24 is a valid and acceptable tool to quantify physical activity levels in this population. The instrument is a standardized physical activity measure that measures all activity, regardless of type or intensity, which may be ideal for women undergoing chemotherapy.