TTRB Activity Levels
EVENT
This analysis was used to estimate the time at which the participants resumed their typical healthy behavior patterns following an ILI event (ie, the TTRB). The analysis was performed on residuals from the baseline model. Residuals were smoothed with a rolling centered 3-day mean to reduce spurious patterns that could interfere with the TTRB.The TTRB was computed as follows: for each individual and each activity feature, the mean and SD during the baseline period were calculated. Then, all days within 1× SD of the individual’s baseline mean were considered to be within the healthy range of behavior. Starting with the day of ILI onset, the first of 2 consecutive days on which the activity feature was within the range of healthy behavior (within 1× SD of baseline activity) was determined. For RHR, the TTRB was computed for each individual by taking the mean and SD of RHR. Then, the first day that was followed by 14 days that had <32% of values outside the healthy range (greater than 1× SD from baseline activity) was identified. Our original analyses included 6 different methods of computing the TTRB, and 3 smoothing functions were applied to the residuals. As with the cumulative ILI burden, only 1 TTRB method and 1 smoothing function per activity feature are reported here, and redundant results have been omitted. 