Meta-analysis Of The Effects Of Smartphone App Interventions On Weight Loss And Physical Activity And Exploration On Active Behavior Change Techniques

Objective:Overweight and obesity are major risk factors for a wide range of chronic diseases,and contribute substantially to the global burden of disease,death and disability.Balancing calorie intake,activity and sedentary behavior are critical and fundamental to lose and maintain weight.Besides,physical inactivity also is a leading risk factor of noncommunicable diseases and deaths.Several meta-analyses have presented the efficacy of smartphone applications on weight loss and physical activity in patients with different body conditions,which conceivably obtained different results,e.g.,BMI and physical activity.While a mobile APP-based weight-loss intervention is actually a multi-component and complex program.For a better replication and refinement of this kind of intervention,it is necessary to decompose the intervention and unlock the"black box"of the intervention to identify the truly active components.Given these factors and considering that more randomized controlled trials(RCTs)on mobile app interventions have been newly published,we conducted this meta-analysis to conclusively evaluate the effectiveness of smartphone apps on weight loss and physical activity in adults with overweight or obesity.This study also described the application of behavior change techniques(BCTs)in mobile APP intervention,and tapped into the potential effective BCTs of such intervention on the efficacy.Methods:Scopus,Embase,Pub Med,Web of Science,The Cochrane Library and Science Direct were searched for relevant studies from the incipience of the databases to September 8,2020.A standardized instrument,Quality Assessment Tool for Quantitative Studies(as developed by the Effective Public Health Practice Project),was applied on quality assessment.Random-effects models were used to pool WMD and SMD across trials.Two researchers independently used behavior change technique taxonomy volume1(BCTTv1)to code the BCT used in the intervention in each study.Univariate and multivariate meta-regressions were used to explore sources of heterogeneity and to identify effective BCT.Results:The literature searches yielded 13 221 citations,of which 31trials met the eligibility criteria,involving a total of 3990 participants.For study quality,8 studies were rated as‘strong’,15 studies were rated as‘moderate’,and 8 studies were rated as‘weak’.Compared with the control group,mobile apps intervention resulted in significant decreases in body weight of-1.34 kg(95%CI:-1.67,-1.02)and in BMI of-0.48 kg/m~2,(95%CI:-0.58,-0.37),and also leaded to significant improvement in MVPA,SMD=0.50,(95%CI:0.32,0.68)and steps per day,1983 steps per day,(95%CI:1111,2856).There was also an evidence of reducing sedentary time,-14.76 min/day,(95%CI:-29.12,-0.40).The combination of gamification in the intervention is beneficial to improve physical activity.Subgroup analysis found that the effectiveness of the intervention could only be maintained in the short term(e.g.,6 months).Thirty-one studies involved a total of 31intervention groups.The top five most used BCTs were 4.1.Instruction on how to perform the behavior,3.1.Social support(unspecified),2.4.Self-monitoring of outcome(s)of behavior,1.4.Action planning and 2.3.Self-monitoring of behavior.Univariate meta-regression analysis found that BCTs 2.4.Self-monitoring of outcome(s)of behavior(β=-0.83,P=0.01),2.7.Feedback on outcome(s)of behavior(β=-0.83,P=0.01)and 12.5.Adding objects to the environment(β=-0.88,P=0.01)were associated with weight reduction.While BCT 7.1.Prompts/cues(β=0.97,P=0.03)went against weight loss.Multivariate meta-regression analysis found that self-monitoring of and feedback on outcome(s)of behavior was associated with weight loss(β=-0.64,P=0.03).Conclusions:1.In overweight and obese adults,the application of smartphone APP intervention can promote weight loss and increase the level of physical activity in short term,and improve sedentary behavior.2.BCTS self-monitoring of and feedback on performance outcome(s)of behavior are conducive to weight loss,BCT adding objects to the environment may be related to weight loss promotion,and BCT Prompts/cues may be detrimental to weight loss.