In a case study using an ICBT program for SAD, Botella and coworkers in Spain found initial empirical support for the treatment efficacy (Botella et al. 2004). This same program was further tested in a series of case studies (Botella et al. 2007) presenting efficacy data from 12 social phobia patients with good results. The Swedish team (Carlbring et al. 2006) published an open trial in which 26 participants were treated with an ICBT program plus weekly therapist contact via email. The results showed that the participants improved significantly on all outcomes and the treatment gains were maintained or improved at the 6-month follow-up. All these studies provided preliminary evidence supporting the use of ICBT programs for people diagnosed with SAD.

Table 4.2 presents an overview of randomized clinical trials investigating the effect of Internet-based CBT. Andersson and coworkers published the first RCT (Andersson et al. 2006) on the efficacy of ICBT for SAD which was then followed by several trials with the same ICBT program (see below). In this first RCT, 64 participants were randomly assigned to the ICBT program supported by email contact of a named therapist plus two in vivo exposure sessions in a group format, or a waiting list control condition. The results revealed that the ICBT condition was significantly more efficacious than the control condition with treatment gains maintained at 1-year follow-up. The authors also published results on long-term outcome (30-month follow-up) which suggested that the long-term effects seen in previous live treatment CBT for SAD trials also occur in Internet-delivered treatment (Carlbring et al. 2009). Using largely the same treatment but without in vivo exposure sessions, Hedman and coworkers found that treatment gains were sustained 5 years after treatment (Hedman et al. 2011a). The efficacy of ICBT for SAD has also been demonstrated in several trials conducted in Australia. Titov and colleagues (2008b) carried out an RCT in which 105 participants with SAD were randomly assigned to an ICBT program or to a waiting list control group. The results showed significant differences between treatment and waiting list participants. As in the trials conducted in Sweden, effects were comparable with those obtained in face-to-face treatment. In Switzerland, Berger and coworkers conducted an RCT (Berger et al. 2009) including 52 individuals with SAD who were randomly assigned either to an ICBT program with minimal therapist contact via email or to a waiting list control group. Significant differences between the two groups were found at posttreatment on all primary outcome measures. The results provided additional support to the hypothesis that ICBT interventions with minimal therapist contact are a promising treatment for SAD. Gallego, Emmelkamp, van der Kooj, and Mees (2011) presented an RCT in which the effects of a Dutch version of the Spanish ICBT for SAD were investigated. Forty-one participants suffering from SAD were randomly assigned to either the ICBT program combined with minimal therapist contact via email or a waiting list control group. The group treated with ICBT was significantly improved from pretest to posttest on all SAD measures, and this condition was significantly more effective than the control group. This study as well as a pilot study of the British team (Stott et al. 2013) provides additional evidence for the efficacy of ICBT for SAD and shows that an ICBT program can be adapted and used with maintained effects in different cultural frameworks.

ICBT has also been compared to traditional face-to-face CBT for SAD. Hedman et al. (2011b) carried out an RCT to investigate whether ICBT was at least as effective as traditional CBT group therapy when treatments are delivered in a psychiatric setting. One hundred and twenty-six individuals with SAD were randomly assigned to one of these two treatment conditions. The results revealed that both conditions made large and similar improvements and it was concluded that ICBT can be as effective as traditional CBT group therapy in the treatment of SAD. Botella and coworkers (2010) conducted an RCT in which 127 participants with a diagnosis of SAD were randomly assigned to three experimental conditions: an ICBT self-administered program, the same CBT treatment applied by a therapist, and a waiting list control group. The data showed that both treatment formats (self-administered and therapist administered) were equally efficacious and superior to the waiting list condition. The treatment gains were maintained at 1-year follow-up. In a study conducted in Australia, Titov et al. (Andrews et al. 2011b) also compared the effectiveness of ICBT with face-to-face CBT group therapy for SAD in an RCT including 75 participants. Both treatment formats yielded significant improvements and there were no significant differences between them. All these results provide evidence showing that both forms of delivering the treatment (face-to-face CBT and ICBT) can be equally effective while the difference in therapist time required is substantial. The results are also consistent with previous findings obtained in ICBT for panic disorder (e.g., Carlbring et al. 2005).

An important line of research has focused on studying the degree of support and guidance needed during the treatment. Tillfors and coworkers (Tillfors et al. 2008) carried out an RCT specifically targeting university students and investigating whether the ICBT self-help program would be more effective if five live group exposure sessions were added. Thirty-eight participants meeting the diagnostic of SAD were randomized into two different treatment groups: ICBT combined with five group exposure sessions or the same ICBT program alone. Both treatment conditions showed significant improvements from pre- to posttest and from pretest to 1-year follow-up on all measured SAD dimensions. The results suggest that adding group exposure sessions did not improve the outcome significantly.

Berger and coworkers (Berger et al. 2011) studied the role and necessity of therapist guidance in an RCT comparing the benefits of a 10-week unguided treatment, with the same intervention complemented with minimal weekly therapist support via email. The study included a third condition, in which the level of support was flexibly stepped up from no support to email or telephone support on demand of the participants. Eighty-one individuals with SAD were randomly assigned to one of the three conditions. Results showed significant improvements in all three treatment groups and no differences between the conditions regarding clinical outcomes, dropout rates, and adherence to treatment. These results provided additional evidence showing that ICBT for SAD is an effective treatment option when therapist guidance is provided but also when no support is provided.

The Australian team also contributed to this line of research carrying out several RCTs. For instance, in a trial by Titov and coworkers (2008c), 98 participants suffering from SAD were randomly assigned to a clinician-assisted ICBT program (email contact with a therapist and participation in an online discussion forum), the same ICBT program but without contact with a clinician, or to a wait list control group. The therapist-guided condition was superior to the self-guided condition, but a subgroup of participants who completed the program benefited considerably from the latter. In a subsequent study, Titov and colleagues (2009a) compared the self-guided treatment with a self-guided plus weekly telephone reminder condition in which participants were called once a week by a research assistant. Results showed that adherence and outcome were better in the condition that included reminders.

Overall, results on unguided treatments for SAD are still inconclusive. However, it is quite surprising that some studies (Berger et al. 2011), including a trial by Furmark and coworkers (Furmark et al. 2009b) in which an unguided treatment for SAD delivered in the form of bibliotherapy with no therapist support was as efficacious as guided ICBT, found no difference between unguided and guided treatments. Data from meta-analyses on ICBT for several disorders indicate better results of guided versus unguided treatments regarding improvements and dropout rates (Richards and Richardson 2012; Spek et al. 2007). It may be that guidance is less important in ICBT for SAD than for other disorders such as depression. However, it may also be that unguided treatments only achieve good therapeutic outcome under specific conditions. In the two studies mentioned above, a proper diagnosis was established and there was a contact with a clinician or the study team during the diagnostic phase. In one uncontrolled study in which there was no contact at all with the researchers, dropout was substantial (Klein et al. 2011). In another study in which the effects of clinician contact in the diagnostic phase was evaluated in an unguided treatment, participation in the structured diagnostic interview did not influence primary outcome but had a beneficial effect on adherence and secondary outcomes (Boettcher et al. 2012a). Clearly, more research is needed with regard to the role of support and contact before and during ICBT for SAD.

Another line of research that addresses questions on the role of support is related to therapists in guided ICBT. Does it matter who provides the support? Titov and coworkers (2009b) found that ICBT for SAD with guidance given by non-clinicians resulted in good outcomes. Andersson and coworkers (Andersson et al. 2012) evaluated the role of therapist experience and found no differences between experienced therapists and therapists with no previous experience in ICBT. However, inexperienced therapists needed more time to provide guidance than experienced therapists. Overall, the findings suggest that ICBT does not require experienced therapists to be effective which is plausible given that (a) the treatment is highly structured and (b) the main component is a self-help program which also incorporates clinical expertise. In addition, it is important to note that non-clinicians and inexperienced therapists were under careful clinical supervision in all studies that included support by inexperienced therapists/coaches.

Another issue that has been examined is the possible role of including additional strategies for enhancing clinical results. For instance, Titov and coworkers (2010a) added motivational enhancement strategies to their ICBT program (understanding and exploring ambivalence about change, enhancing self-efficacy, etc.). Results of an RCT showed that ICBT with or without this additional component was efficacious. Although more participants in the motivational treatment condition completed the treatment lessons (75 % versus 56 %, respectively), no differences between the two conditions were found at posttreatment and at 3-month follow-up.

It is also possible that adding collaborative online group elements such as discussion groups could enhance treatment effects. There is at least indirect evidence that integrating collaborative elements into ICBT could be beneficial. Titov and colleagues could improve small within-group effect sizes for unguided ICBT for SAD (Titov et al. 2008c) by adding a clinician-moderated online discussion forum in a subsequent study. As mentioned previously, in the study by Furmark and coworkers (2009a), an intervention consisting of a self-help guide delivered in the form of bibliotherapy with no therapist support but with access to an online discussion forum was as effective as guided ICBT. Moreover, qualitative analyses of the content of discussions in integrated forums showed that therapeutic mechanisms of change may come into play that are known from research on group psychotherapies (e.g., normalization, altruism, instillation of hope, development of socializing techniques, imitative behavior, cohesiveness (Berger 2011)). However, since to the best of our knowledge there are no studies directly comparing the same internet-based treatment with and without collaborative elements, it is not possible to draw firm conclusions on the effects of integrated online discussion boards.

Still another arena of research explores whether addressing the high comorbidity rates in patients with SAD is beneficial. This was done with unified transdiagnostic treatments (Titov et al. 2010b, 2011; Johnston et al. 2011) and tailored approaches in which the self-help guide is individually tailored to the symptom profile of a patient by providing modules on comorbid problems and disorders such as mood disorders, other anxiety disorders, or insomnia (Berger et al. 2014; Carlbring et al. 2011b; Andersson et al. 2011). Both approaches seem to be effective, but it is not clear whether patients with SAD would benefit more from a transdiagnostic or tailored approach than from a treatment that targets SAD only. There is one study directly comparing a tailored versus standardized disorder-specific approach finding no differences between the two approaches, but this trial included patients with various anxiety disorders and levels of comorbidity (Berger et al. 2014). It is possible that a tailored approach is especially beneficial for subgroups of SAD patients such as individuals with high levels of comorbidity. This could not be tested in the trial mentioned above as the subgroup of SAD patients with high comorbidity rates was too small for appropriate subgroup analyses (Berger et al. 2014). Indeed, in a controlled trial comparing standard ICBT versus a tailored intervention in depression with comorbid problems, it was found that the tailored treatment was better suited to handle more severe disorders (Johansson et al. 2012).