Study Limitations & Recommendations for Future Research

The aim of this study was to investigate the effectiveness of psychological interventions as they were offered in clinical practice. Because it was not appropriate to deny clients access to the service for research purposes, the study sample was not randomised, raising the possibility of problems with internal validity. Despite a number of measures being put in place to reduce threats to internal validity, it is possible that some threats still remained. The two treatment groups differed significantly with regard to sample size, which may have affected the significance of test results due to differences in error variance. Because overall sample sizes were small, study results may not be generalisable to all service users, or to the general cancer population, and should therefore be interpreted with caution. Some participants were also part of a couple, therefore, their data may not be considered to be independent. Although living in the same dwelling, it was anticipated that each participant would complete their own questionnaire independently, without collaboration with their spouse. However, it is possible that some responses given were influenced by the emotions and experiences of the other spouse. This is important because it could be seen to breach one of the assumptions of the statistical processes used. It is possible that the improvements in both groups over time may have been influenced by other factors in addition to treatment

condition. For example, because the intervention group were recruited post- therapy, it is possible that the study sample may have been affected by self- selection bias. That is, clients who benefited from therapy chose to participate in the research, and those who had not, did not. Also, as discussed earlier, the control group was ‘treatment-as-usual’, rather than ‘non-treatment’. Therefore, some participants in the control group received psychological support during the course of the study. Although unlikely, it is also possible that there was a potential time bias, which could have introduced differences in cancer treatment that participants received. This is because the intervention group were recruited post-therapy (T3), with retrospective data being collected at T1 and T2. Whereas the control group were recruited at study commencement (T1), and were followed prospectively (T2 & T3).

Participants in this study were predominantly women with breast cancer. Therefore, it is unknown whether psychological support was just as effective for males or women with other cancers. This is unfortunate, as a recent meta- analysis by Heron (2009) reported that psychological interventions were most beneficial for those who were least likely to receive it (e.g., males and clients with non-breast cancers). This finding suggests that had clients in these groups been more evenly represented in the present study, those in the intervention group would have shown even greater effect sizes. Maori and Pacific Island clients were also under-represented in the study, which is unfortunate given the higher rates of cancer in this population. Further research needs to be conducted within these populations.

In addition to exploring changes in distress over time, this study also attempted to look at possible factors influencing outcome. Research has suggested that clients’ perceptions of the therapeutic experience may differ from that of the therapists’ (Weiss, Rabinowitz & Spiro, 1996). Therefore, interviewing the therapists would have provided important data regarding therapist views of the key aspects of psychotherapy within this specialised clinical setting. Both factors, effective techniques combined with a good therapeutic relationship, have been shown to maximise the effectiveness of therapy (Lambert, 2004). Clients may benefit from effective techniques without any conscious

awareness of what is being used. However, therapists who have been schooled in utilising certain techniques may, at times, not consciously focus on relationship factors, which are also important in ensuring an effective intervention (Lambert, 2004). Additionally, clients’ perceptions of their therapy experience were also obtained three months post-therapy. Therefore, it is possible that clients’ recall of events became less specific over time, instead providing a more global account of their experience. Future research may benefit from talking with clients immediately after therapy has ceased, or during the course of therapy, as more specific technique-related elements of therapy may be identified by clients.

In hindsight, the method for choosing the high- and low-change groups may not have been the most appropriate. Differences in ORS change scores over time were examined at follow-up. Although this provided a unique look at the extended effectiveness of psychological interventions, analyses showed no statistical or qualitative differences between the two groups at the end of therapy. Had low and high-change groups been identified at the end of therapy rather than at follow-up, it is possible that more therapeutic rather than external factors may have been identified as being responsible for treatment outcome. Additionally, rather than comparing those who made the most and least change over time, it may be more clinically beneficial for future studies to compare those who showed a clinically significant change with those who did not, and examine possible explanations for this.