Permissions for the use of subscales were granted by the questionnaire authors, where required, and were purchased for the HADS.
2.3.1. Adaptation of Measures
The wording in-between the subscales in the questionnaire battery was partly instated as a result of the requirements of the NHS ethics committee (see extended paper 2.1.5), and partly served as a primer and contextual cue for the more general measures included on the questionnaire. For example, text inserted prior to the first item of the Brief COPE items asked participants to consider the items in relation to their cancer.
Some items on the Brief IPQ (item numbers 2,3,7,8) were altered, in line with recommendations from the author (Broadbent et al., 2015) and researchers investigating the validity of the Brief IPQ for cancer populations (Price et al., 2012; van Oort, Schröder, & French, 2011). Alterations to the wording of items made them first person, cancer-specific, and in some cases improved their clarity (van Oort et al., 2011). For example, an item which asked about perceived control over cancer, was replaced by perceived influence over cancer, with the authors’ rationale for this change being that control was abstract and not necessarily internally-attributed. One original timeline question, which had poor psychometric properties for participants with short prognoses (Price et al., 2012), was replaced by an original item from the IPQ-Revised, from which the Brief IPQ was derived and which has well-established validity in cancer populations (Ashley et al., 2013). The replaced item still targeted
perceived life expectancy: ‘How long do you think your illness will continue?’ was therefore substituted for ‘I expect to have this cancer for the rest of my life’.
2.3.2. Justification of Measures
Two questionnaires were included in their brief forms, to prevent over-burdening participants with cancer, and to prevent high rates of study attrition. The six standardised questionnaires chosen to make up the questionnaire battery are frequently used in research on distress and quality of life in health populations, and are therefore easily related to other findings. The exception to this is the DAS, as death anxiety is not routinely measured. However, the DAS has been used in cancer research, but far less frequently than measures of general anxiety, such as the HADS. The DAS remains the most widespread measure of death anxiety (Neimeyer, Moser, & Wittkowski, 2003), and was less lengthy to complete than other death anxiety measures available; a factor which was key given the likely physical health limitations of some participants. The Brief IPQ has good psychometric properties (Broadbent et al., 2015), in terms of its sensitivity to change and validity, and has been used in both long and short form in cancer populations. However, the internal reliability as measured using Cronbach’s alpha (α=.38) was lower for this study than in research elsewhere with cancer patients, possibly due to the changes made to scale items to improve their readability and validity for the population. As the scale attempts to assess “both emotional and cognitive representations of illness” (Broadbent et al., 2015, p.631), it was used here as a broader measure of the experience of cancer, in recognition of the complex and multi-factorial nature of illness.
Although there has been some concern as to whether the AAQ II has poor validity in measuring several ACT processes, which may conflate with distress outcomes (Wolgast, 2014), the AAQ II may be most reflective of experiential acceptance over any other ACT process and therefore has utility within this study, as well as ubiquity in its use elsewhere in the literature (Francis, Dawson, & Golijani-Moghaddam, in press). Furthermore, at the time of beginning this study, the AAQ II was the only validated measure of experiential acceptance, though a later further measure of acceptance has since been developed (Francis et al., in press).
There is a wealth of literature that studies response styles, as measured by the Brief COPE, and outcomes of quality of life and distress. However, little research has used the AAQ II alongside the Brief COPE, despite experiential avoidance potentially mediating the effects of coping styles upon distress outcomes (Fledderus, Bohlmeijer, & Pieterse, 2010). One potential reason for the lack of inclusion of the AAQ II in cancer research is that acceptance is an item listed on the Brief COPE, though as explained below there are theoretical contrasts between the two types of avoidance. This study included both the Brief COPE and AAQ II measures, in order to assess the contribution of acceptance to the outcomes well-known to be influenced by different Brief COPE styles in cancer patients.
Acceptance as measured by the Brief COPE alludes to ‘accepting the fact that the stressful event has occurred and is real’, i.e. a form of cognitive awareness of a situation rather than of one’s innermost states. Carver (1982) stated that this accepting coping strategy allows people to actively engage with situations, and whilst acceptance on the Brief COPE differs in its definition from acceptance in ACT, both may facilitate approach rather than avoidant responses. The two items were included in bivariate correlations to see whether they were associated with each other, and related to outcomes in the same direction.
The FACT-G is cancer-specific, and therefore targets aspects of quality of life known to be affected by cancer, through items which ask about side effects of treatment, pain, and concerns about dying, for example. Although alternative measures of quality of life are frequently used with cancer patients, such as the SF-6D or EQ5D, these measures are expensive to use and are also not disease-specific. Thus, the FACT-G was considered a less global, and more specific option to capture cancer-related quality of health domains for this population; although the scores from the FACT-G can be mapped on to those of the EQ5D and the SF-6D to improve generalisability across research projects, as required (Teckle et al., 2013). Although not initially designed for patients in remission, the FACT-G is still useful and valid for historical cancer patients,
despite the fact some items such as ‘I have nausea’ may no longer be relevant (Yost et al., 2013).
2.4. Details of Additional Analyses