Effectiveness of online interventions in preventing depression: a protocol for systematic review and meta-analysis of randomised controlled trials

INTRODUCTION: Although evidence exists for the efficacy of psychosocial interventions in preventing depression, little is known about its prevention through online interventions. The objective of this study is to conduct a systematic review and meta-analysis of randomised controlled trials assessing the effectiveness of online interventions in preventing depression in heterogeneous populations. METHODS AND ANALYSIS: We will conduct a systematic review and meta-analysis of randomised controlled trials that will be identified through searches of PubMed, PsycINFO, WOS, Scopus, OpenGrey, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov and Australia New Zealand Clinical Trials Register. We will also search the reference lists provided in relevant studies and reviews. Experts in the field will be contacted to obtain more references. Two independent reviewers will assess the eligibility criteria of all articles, extract data and determine their risk of bias (Cochrane Collaboration Tool). Baseline depression will be required to have been discarded through standardised interviews or validated self-reports with standard cut-off points. The outcomes will be the incidence of new cases of depression and/or the reduction of depressive symptoms as measured by validated instruments. Pooled standardised mean differences will be calculated using random-effect models. Heterogeneity and publication bias will be estimated. Predefined sensitivity and subgroup analyses will be performed. If heterogeneity is relevant, random-effect meta-regression will be performed. ETHICS AND DISSEMINATION: The results will be disseminated through peer-reviewed publication and will be presented at a professional conference. Ethical assessment is not required as we will search and assess existing sources of literature. TRIAL REGISTRATION NUMBER: CRD42014014804; Results.