Table 4.
A summary of meta-analyses.
| Review and comparisona | Number of included articles | Outcome (units) and follow-up | N | Heterogeneityb | Effect sizec (95% CI) | P | ||||
| χ2 (df) | P | T2 | I2 | |||||||
| Neve et al, 2009 [14] | ||||||||||
| Web vs control | 3 | Weight loss (kg) | 151 | 12.8 (2) | .002 | — | 84.4% | 0.73 (–0.6, 1.51) WMD | .07 | |
| Enhanced Web vs basic Web | 3 | Weight loss (kg) | 217 | 3.8 (3) | .28 | — | 21% | 2.24 (1.27, 3.21)d SMD | <.001 | |
| Web vs control | 2 | Weight loss maintenance (kg) | 409 | 0.02 (1) | .90 | — | –0.30 (–0.34,–0.26)d WMD | <.001 | ||
| Web vs face-to-face | 2 | Weight loss maintenance (kg) | 182 | 12.2 (3) | .007 | — | 76% | 1.80 (–1.18, 4.79) WMD | .24 | |
| Kodama et al, 2012 [15] | 23 | Weight loss, weight loss maintenance (kg) | 8697 | — | <.001 | — | 84% | –0.68 (–1.29,–0.08) WMD | .03 | |
| Reed et al, 2012 [17] | ||||||||||
| Intervention with Web vs without Web | 5 | Weight loss (kg) | 336 | 0.7 (5) | .98 | 0.00 | 0% | –1.48 (–2.52,–0.43) WMD | .006 | |
| Web vs non-Web | 5 | Weight loss (kg) | 544 | 14.2 (5) | .01 | 3.61 | 65% | 0.36 (–1.80, 2.53) WMD | .74 | |
| Web vs non-Web | 4 (articles published in 1995 or later) | Weight loss (kg) | 538 | 1.7 (4) | .78 | 0.00 | 0% | 1.47 (0.13, 2.81) WMD | .03 | |
| Intervention with Web vs without Web | 4 | Weight loss (kg); short-term follow-up | 100 | 0.2 (4) | >.99 | 0.00 | 0% | –1.89 (–3.41,–0.38) WMD | .01 | |
| Intervention with Web vs without Web | 1 | Weight loss (kg); long-term follow-up | 236 | NA | NA | NA | NA | –1.10 (–2.55, 0.35) WMD | .14 | |
| Intervention with Web vs without Web | 2 | Weight loss (kg); short-term follow-up | 53 | 0.04 (1) | .85 | 0.00 | 0% | –1.95 (–3.50,–0.40) WMD | .01 | |
| Intervention with Web vs without Web | 3 | Weight loss (kg) long-term follow-up | 283 | 0.03 (3) | >.99 | 0.00 | 0% | –1.08 (–2.50,–0.34) WMD | .14 | |
| Intervention with Web vs without Web | 2 (articles published prior to 1995) | Weight loss (kg) | 47 | 0.02 (2) | .99 | 0.00 | 0% | –0.63 (–7.91, 6.66) WMD | .87 | |
| Intervention with Web vs without Web | 3 (articles published in 1995 or later) | Weight loss (kg) | 289 | 0.6 (2) | .72 | 0.00 | 0% | –1.50 (–2.55, 0.44) WMD | .006 | |
| Intervention with Web vs without Web | 3 | Weight loss (BMI) | 380 | 0.8 (2) | .67 | 0.00 | 0% | –0.43 (–0.83,–0.03) WMD | .04 | |
| Web vs non-Web | 2 | Weight loss (BMI) | 51 | 0.3 (2) | .88 | 0.00 | 0% | 0.44 (–1.15, 2.03)c WMD | .59 | |
| Web vs control | 2 | Weight loss (kg) | 511 | 0.04 (1) | .84 | 0.00 | 0% | −1.5 (−2.1, −0.9) MD | <.001 | |
| Wieland et al, 2012 [18] | ||||||||||
| Web vs control | 2 | Weight loss maintenance (kg) | 897 | 0.7 (1) | .41 | 0.00 | 0% | −0.7 (−1.2, −0.2) MD | .004 | |
| Web vs face-to-face | 2 | Weight loss maintenance (kg) | 897 | 2.9 (1) | .09 | 0.41 | 66% | 0.5 (−0.5, 1.6) MD | .32 | |
| Grunenberg et al, 2013 [21] | ||||||||||
| Web vs control | 5 | Weight loss (BMI) | 727 | 10.5 (4) | .03 | 0.15 | 62% | –0.49 (–0.95,–0.03) MD | .04 | |
| Web vs control | 5 | Weight loss (kg) | 727 | 16.7 (4) | .002 | 1.46 | 76% | –1.32 (–2.59,–0.06) MD | .04 | |
a Web vs control: Web-based intervention vs control condition (minimal intervention); enhanced Web vs basic Web: enhanced Web-based interventions vs basic Web-based interventions; Web vs face-to-face: Web-based intervention vs face-to-face intervention; intervention with Web vs intervention without Web: adding a Web-based component to an intervention vs the same intervention without the Web-based component; Web vs non-Web: Web-based interventions vs non-Web-based comparable interventions.
b Ι2: Percentage of the variation across studies attributable to study heterogeneity rather than chance, indicating the level of inconsistency across study results; Τ2: between-study variance.
c Effect sizes were retrieved from original articles reporting a statistically significant pooled effect estimated from at least two trials. All studies except for those indicated used a random effects model to calculate the aggregated effect size. MD: mean difference; SMD: standardized mean difference (Cohen d; standardized weighted aggregated average difference score between conditions across primary studies that use different outcome measures/metrics; to facilitate aggregation across measures/metrics, the between-condition difference for each primary study is converted to standard deviation units that are then weighted with primary studies with more precise estimates carrying more weight in aggregation); WMD: weighted mean difference (unstandardized weighted aggregated average difference score between conditions across primary studies that use the same outcome measure/metric; the between-condition difference for each primary study is weighted with primary studies with more precise estimates carrying more weight in aggregation).
d A fixed effect model was used to calculate the aggregated effect size.