Open AccessUnderstanding mechanisms of integrated behavioral therapy for co-occurring obesity and depression in primary care: a mediation analysis in the RAINBOW trial
Author(s) -
Lisa G. Rosas,
Lan Xiao,
Nan Lv,
Phillip W. Lavori,
Elizabeth M. Venditti,
Mark Snowden,
Joshua M. Smyth,
Megan A. Lewis,
Leanne M. Williams,
Trisha Suppes,
Andrea N. Goldstein-Piekarski,
Jun Ma
Publication year - 2020
Publication title -
translational behavioral medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 39
eISSN - 1869-6716
pISSN - 1613-9860
DOI - 10.1093/tbm/ibaa024
Subject(s) - mediation , path analysis (statistics) , body mass index , randomized controlled trial , medicine , intervention (counseling) , depression (economics) , obesity , weight loss , clinical psychology , cognitive behavioral therapy , psychology , physical therapy , psychiatry , economics , macroeconomics , statistics , mathematics , political science , law
The RAINBOW trial demonstrated that an integrated collaborative care intervention was effective for improving weight and depression. This study examined mediation of the treatment effect by a priori specified lifestyle behaviors and cognitive functioning. Participants were randomized to a 12-month integrated intervention (n = 204) or usual care (n = 205). Body mass index (BMI) and 20-item Depression Symptom Check List (SCL-20) were co-primary outcomes (Y). To examine mediation, we assessed (a) the effect of the integrated intervention (X) on lifestyle behaviors (diet and physical activity) and cognitive functioning (problem-solving; M, X→M path a) and (b) the association of these behaviors with BMI and SCL-20 (M→Y path b). Mediation existed if paths a and b were significant or if path a and the product of coefficients test (paths a and b) were significant. Compared with usual care, the intervention led to significant improvements in leisure time physical activity (201.3 MET minutes/week [SD, 1,457.6]) and total calorie intake (337.4 kcal/day [818.3]) at 6 months but not 12 months (path a). These improvements were not significantly associated with improvements in BMI or SCL-20 (path b). However, avoidant problem-solving style score and increased fruit and vegetable intake significantly correlated with improvements in BMI at 6 and 12 months, respectively. Also, increased fruit and vegetable intake, higher dietary quality, and better problem-solving abilities significantly correlated with improvements in SCL-20 at 6 and 12 months. These findings did not support the hypothesized mediation, but suggest lifestyle behaviors and cognitive functioning to target in future intervention optimization.