Introduction: Weight loss interventions are traditionally delivered face-to-face. Telephone delivery may overcome some barriers to accessing face-to-face programs and provide a useful delivery modality, being ubiquitous, easy to access regardless of geographic location and suitable for long-term contact. We systematically reviewed the evidence on the effectiveness of telephone-delivered weight loss interventions (compared to control and face-to-face) in overweight and obese adults. Initial weight loss interventions and extended care interventions for weight loss maintenance were included.
Methods: A structured search of six databases was conducted for articles published until May 2013. Included studies were randomized trials evaluating interventions in adults with the primary aim to achieve weight loss (or weight loss maintenance) and with at least 50% of intervention contacts in one of the study groups delivered via telephone. Two investigators independently reviewed search results for eligible studies and extracted data. Meta-analyses were by fixed effects when studies were homogeneous or random effects (DerSimonian-Laird) when heterogeneity was present.
Results: 23 studies involving 7,321 participants were eligible. Eighteen studies (5,009 participants) evaluating initial weight loss interventions reported telephone versus control (or brief intervention) comparisons of weight loss (kg). Random effects models showed a significant benefit of telephone over control (weighted mean difference [95%CI]: -2.50 [-3.35, -1.65] kg). Five studies (1,059 participants) compared telephone with face-to-face intervention, with equivalent contact in each modality. Meta-analysis revealed no significant difference between modalities for initial weight loss (telephone – face-to-face: -0.77 [-1.77, 0.23] kg). Three studies (1,610 participants) evaluating extended care interventions reported telephone versus brief intervention comparisons of weight loss maintenance (kg). Random effects models showed significantly less weight regain with the telephone versus brief intervention: -1.68 [-2.39, -0.96] kg.
Conclusions: Evidence suggests that telephone-delivered weight loss interventions are effective and can achieve similar weight loss outcomes as those delivered face-to-face. Comparative cost-effectiveness studies are needed.