Validity of Two Awake Wear-Time Classification Algorithms for activPAL in Youth, Adults, and Older Adults.
DOI: 10.1123/jmpb.2020-0045; PMCID: PMC8386818
Background: The authors assessed agreement between participant diaries and two automated algorithms applied to activPAL (PAL Technologies Ltd, Glasgow, United Kingdom) data for classifying awake wear time in three age groups.
Methods: Study 1 involved 20 youth and 23 adults who, by protocol, removed the activPAL occasionally to create nonwear periods. Study 2 involved 744 older adults who wore the activPAL continuously. Both studies involved multiple assessment days. In-bed, out-of-bed, and nonwear times were recorded in the participant diaries. The CREA (in PAL processing suite) and ProcessingPAL (secondary application) algorithms estimated out-of-bed wear time. Second- and day-level agreement between the algorithms and diary was investigated, as were associations of sedentary variables with self-rated health.
Results: The overall accuracy for classifying out-of-bed wear time as compared with the diary was 89.7% (Study 1) to 95% (Study 2) for CREA and 89.4% (Study 1) to 93% (Study 2) for ProcessingPAL. Over 90% of the nonwear time occurring in nonwear periods >165 min was detected by both algorithms, while
Conclusion: The automated awake wear-time classification algorithms performed similarly to the diary information on days without short (≤2.5-2.75 hr) nonwear periods. Because both diary and algorithm data can have inaccuracies, best practices likely involve integrating diary and algorithm output.
J Meas Phys Behav
accelerometer; non-wear; processing; sedentary
Carlson JA, Tuz-Zahra F, Bellettiere J, et al. Validity of Two Awake Wear-Time Classification Algorithms for activPAL in Youth, Adults, and Older Adults. J Meas Phys Behav. 2021;4(2):151-162. doi:10.1123/jmpb.2020-0045