Abstract: Fifteen studies (N= 2012) were included in analyses. We assessed the risk of bias for included studies as low overall. We identified nine high 'risk of bias' assessments, 22 unclear, and 59 low 'risk of bias' assessments. Most judgements of a high risk of bias were due to inadequate reporting. Analyses revealed seven effects. Participants with headache conditions receiving psychological therapies delivered via the Internet had reduced pain (number needed to treat to benefit = 2.72, risk ratio 7.28, 95% confidence interval (CI) 2.67 to 19.84, p < 0.01) and a moderate effect was found for disability post-treatment (standardised mean difference (SMD) ‒0.65, 95% CI ‒0.91 to ‒0.39, p < 0.01). However, only two studies could be entered into each analysis; hence, findings should be interpreted with caution. There was no clear evidence that psychological therapies improved depression or anxiety post-treatment (SMD −0.26, 95% CI −0.87 to 0.36, p > 0.05; SMD −0.48, 95% CI −1.22 to 0.27, p > 0.05), respectively. In participants with non-headache conditions, psychological therapies improved pain post-treatment (p < 0.01) with a small effect size (SMD −0.37, 95% CI −0.59 to −0.15), disability post-treatment (p < 0.01) with a moderate effect size (SMD −0.50, 95% CI −0.79 to −0.20), and disability at follow-up (p < 0.05) with a small effect size (SMD −0.15, 95% CI −0.28 to −0.01). However, the follow-up analysis included only two studies and should be interpreted with caution. A small effect was found for depression and anxiety post-treatment (SMD −0.19, 95% CI −0.35 to −0.04, p < 0.05; SMD −0.28, 95% CI −0.49 to −0.06, p < 0.01), respectively. No clear evidence of benefit was found for other follow-up analyses. Analyses of adverse effects were not possible. No data were presented on satisfaction/acceptability. Only one study could be included in an analysis of the effect of psychological therapies on quality of life in participants with headache conditions; hence, no analysis could be undertaken. Three studies presented quality of life data for participants with non-headache conditions; however, no clear evidence of benefit was found (SMD −0.27, 95% CI −0.54 to 0.01, p > 0.05). There is insufficient evidence to make conclusions regarding the efficacy of psychological therapies delivered via the Internet in participants with headache conditions. Psychological therapies reduced pain and disability post-treatment; however, no clear evidence of benefit was found for depression and anxiety. For participants with non-headache conditions, psychological therapies delivered via the Internet reduced pain, disability, depression, and anxiety post-treatment. The positive effects on disability were maintained at follow-up. These effects are promising, but considerable uncertainty remains around the estimates of effect. These results come from a small number of trials, with mostly wait-list controls, no reports of adverse events, and non-clinical recruitment methods. Due to the novel method of delivery, the satisfaction and acceptability of these therapies should be explored in this population. These results are similar to those of reviews of traditional face-to-face therapies for chronic pain.

Plain-language summary: Four databases were searched up to November 2013. We found 15 trials that met our inclusion criteria. Four trials included individuals with headache pain, 10 trials included individuals with non-headache pain, and one trial included individuals with both headache and non-headache pain. We looked at data about pain, disability, depression, and anxiety immediately after the end of treatment and between 3 to 12 months follow-up. We also looked at how satisfied people were with the treatments, and its effects on their quality of life. We found that for people with headache pain, pain symptoms and disability scores improved immediately following the end of treatment. However, only two trials could be entered into each of these analyses and so findings should be treated with caution. For people with non-headache pain, pain, disability, depression, and anxiety improved immediately after the end of treatment. Disability was also improved at follow-up. Only one study recorded quality of life scores in individuals with headache pain, so we were unable to analyse the results. Three studies presented quality of life scores for individuals with non-headache pain immediately following treatment. We did not find that quality of life improved after receiving the therapy. No data could be analysed on treatment satisfaction/acceptability. We conclude that these findings are promising for psychological treatments delivered via the Internet for the management of chronic pain in adults, but more trials are needed to determine the efficacy of such therapies.