Accelerometer-measured versus self-reported physical activity levels in women before and up to 48 months after Roux-en-Y Gastric Bypass

BACKGROUND: Roux-en-Y Gastric Bypass (RYGB) patients overestimate their time spent in moderate-to-vigorous physical activity (MVPA) to a greater extent post-surgery than pre-surgery. However, there is no data on discrepancy between self-reported and accelerometer-measured MVPA beyond nine months post-RYGB. The aim was to investigate how the duration of MVPA (main outcome) differs when comparing a self-administered questionnaire to accelerometer-data from pre-surgery and up to 48 months post-RYGB. METHODS: Twenty-six (38%) RYGB-treated women with complete data from the original cohort (N = 69) were included. Participants were recruited from five Swedish hospitals. Mean pre-surgery BMI was 38.9 (standard deviation (SD) = 3.4) kg/m(2) and mean age 39.9 (SD = 6.5) years. MVPA was subjectively measured by a self-administered questionnaire and objectively measured by the ActiGraph GT3X+ accelerometer at 3 months pre-RYGB and 9- and 48 months post-RYGB. Means and SD were calculated at 3 months pre- and 9- and 48 months post-RYGB. We calculated the P-values of the differences with Wilcoxon Signed-Rank test. For correlations between the self-administered questionnaire and the accelerometers, Spearman’s rank correlation was used. RESULTS: Participants significantly overestimated (i.e. self-reported more time spent in MVPA compared to accelerometry) their MVPA in a higher degree post- compared to pre-RYGB surgery. Compared to pre-surgery, self-reported MVPA increased with 46.9 and 36.5% from pre- to 9- and 48 months, respectively, whereas changes were a 6.1% increase and 3.5% decrease with accelerometers. Correlations between self-reported and accelerometer-measured MVPA-assessments were poor at all measurement points (r = 0.21–0.42) and only significant at 48 months post-RYGB (P = 0.032). CONCLUSIONS: The discrepancy between self-reported and objectively assessed MVPA within the same individual is greater up to 48 months post-RYGB compared to before surgery. To help bariatric patients understand and hopefully increase their physical activity behaviors post-surgery, objective measures of physical activity should be used.