Visual Inspection for Determining Days When Accelerometer Is Worn: Is This Valid?

Area of Science:

• Physical activity monitoring
• Biomedical data analysis

Background:

• Participant logs are traditionally used to determine accelerometer wear days in mail study designs.
• Incomplete participant logs can compromise data accuracy in accelerometer research.

Purpose of the Study:

• To evaluate the validity of visual inspection of accelerometer data as an alternative to participant logs for ascertaining wear days.
• To assess the reliability of visual inspection when participant logs are missing in mail-based studies.

Main Methods:

• Compared visual inspection of accelerometer output with participant logs in 197 women (mean age, 71.0 yr).
• Two independent raters, masked to log status, analyzed daily accelerometer count graphs to determine wear days.
• Calculated sensitivity, specificity, and interrater agreement for visual inspection.

Main Results:

• Visual inspection demonstrated high accuracy, with sensitivity at 99.7% and specificity around 97.0-97.2% for both raters.
• Interrater agreement for visual inspection was excellent at 99.5%.
• The median number of valid wear days determined by both methods was consistently 7 (7-7).

Conclusions:

• Visual inspection of accelerometer data is a valid and reliable method for determining wear days.
• This technique serves as a viable alternative to supplement or replace missing participant logs in mail study designs.
• The findings support the use of visual inspection to enhance data completeness and accuracy in accelerometer research.