Trait anxiety as an independent predictor of poor health‐related quality of life and post‐traumatic stress symptoms in rectal cancer

The number of people who can count themselves as cancer survivors has increased dramatically, due to advances in early detection and successful treatment, the ageing of the population, and broader definitions of ‘survivorship’ (Rowland, Hewitt, & Ganz, 2006). With these changes has come increased interest in the ways in which cancer and its treatment impacts survivors, in terms of both objective and subjective outcomes. Objective outcomes include side-effects of treatment, long-term and late effects of treatment, and economic burden. Subjective (i.e. patient-reported) outcomes include treatment satisfaction, health-related quality of life (HRQoL) and, in some, symptoms of post-traumatic stress (Aziz, 2007; Gotay, Lipscomb, & Snyder, 2005; Kangas, Henry, & Bryant, 2002). Interestingly, objective and subjective outcomes often do not coincide. A common finding is that HRQoL among cancer survivors is more favourable than would be expected, often comparable to healthy controls, even when deleterious biomedical effects persist (Gotay et al., 2005; Schwartz & Sprangers, 2002; Rapkin & Schwartz, 2004). However, most studies report only mean values, which do not reflect the fact that HRQoL data are typically skewed. Although there may be a clustering of patients towards the favourable end of the distribution, the longer tail represents a great number of patients who report relatively poor HRQoL (Curran et al., 2000; Cella et al., 2003). Also, those reporting poor HRQoL might not differ appreciably from their higher HRQoL counterparts in terms of objective health status (Wilson & Cleary, 1995). The question we address in this study is this: why do some cancer survivors report poor HRQoL when their apparent medical status is not different from their peers? One explanation for the mismatch between subjective and objective outcomes could be that subjective measures are inherently open to the influence of patients’ individual perspectives and predispositions, while objective biomedical outcomes are not (Gotay et al., 2005; Schwartz & Sprangers, 2002; Rapkin & Schwartz, 2004; Cella et al., 1993). For example, one possible influence on HRQoL is patients’ affective disposition, which would not be expected to significantly influence biomedical outcomes related to cancer. There is a broad base of evidence demonstrating that negative affective traits (i.e. tendencies towards depression, anxiety, and pessimism) have a potent influence on self-reported physical symptoms and well-being, often outweighing the influence of objective markers of functioning (Pennebaker, 2000; Watson & Pennebaker, 1989). In the present study, we hypothesized that a commonly measured form of negative affect (trait anxiety) would predict self reports of well-being (HRQoL and post-traumatic stress symptoms, PTSS), while controlling for objective medical outcomes (stage of disease, presence of colostomy, and severity of faecal incontinence). Only a few studies have investigated relationships between various measures of negative affect and HRQoL. In the original validation study of the Functional Assessment of Cancer Therapy measure (FACT; Cella et al., 1993), the FACT-G summary score was inversely related to scores on the Brief Profile of Mood States (BPOMS; Cella et al., 1987) as well as to scores on the Taylor Manifest Anxiety Scale (Taylor, 1953). In a study of the FACT-Colorectal measure (FACT-C; Ward et al., 1999), all of the summary and subscale scores were inversely related to the BPOMS (Cella et al., 1987) and the Profile of Mood States - Short Form (McNair, Lorr, & Droppleman, 1992). In a study of patients with colorectal cancer (Yoo, Kim, Eremenco, & Han, 2005), all subscale and total scores on the FACT-C (Ward et al., 1999) were inversely related to scores on both the BPOMS(Cella et al., 1987) and the Neuroticism scale of the Eysenck Personality Questionnaire (Eysenck & Eysenck, 1976). And lastly, in a study of 60 cancer patients conducted at the time of surgical follow-up, patients’ global HRQoL as measured by the Quality of Life Questionnaire (Aaronson et al., 1993) was inversely related to their scores on the Negative Affect scale of the Positive and Negative Affect Schedule (Watson, Clark, & Tellegen, 1988), but was not correlated with physicians’ ratings of their HRQoL or overall physical condition (Koller et al., 1996). Another patient-reported outcome that has received increased interest is post-traumatic stress disorder (PTSD). With the introduction of the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 1994), the criteria for PTSD were altered to allow the inclusion of life-threatening illnesses as traumatic events. Since the publication of DSM-IV in 1994, scores of articles have been published on the relation between various serious illnesses and either PTSD or PTSS. Of the studies that have been done with regard to cancer, most have focused on either breast cancer or on childhood cancer survivors and their parents, while relatively few studies have looked at these issues in colon and rectal cancers (cf. Salsman, Segerstrom, Brechting, Carlson, & Andrykowski, 2009). While most cancer patients never meet diagnostic criteria for PTSD, a high proportion of patients experience subclinical PTSS following diagnosis (Kangas et al., 2002; Deimling, Kahana, Bowman, & Schaefer, 2002). Although PTSS will decline considerably within the first few months, such symptoms can trouble some patients for years (Kangas et al., 2002). Similar to the discrepancies regarding HRQoL, neither the incidence of PTSD nor the magnitude of PTSS is clearly related to biomedical aspects of the disease, but they have been linked to various measures of negative affect (Kangas et al., 2002; Kangas, Henry, & Bryant, 2005; Palmer, Kagee, Coyne, & DeMichele, 2004). In a longitudinal study of cancer patients, scores on the Beck Depression Inventory (Beck, Steer, & Brown, 1996) and the Trait scale of the State-Trait Anxiety Inventory (Spielberger, Gorsuch, Lushene, Vagg, & Jacobs, 1970), administered within 1 month of diagnosis, were correlated with both PTSD caseness and PTSS severity, which were assessed at 6 months post-diagnosis (Kangas et al., 2005). All of the studies just described showed that greater levels of negative affect were related to either poorer HRQoL or more problems with PTSS. However, most of those studies were cross-sectional and most used measures of negative mood state rather than trait negative affect, which has made the direction of causality difficult to infer. The purpose of the present longitudinal study was to examine the influence of stable negative affective disposition on both HRQoL and PTSS in a sample of rectal cancer survivors while controlling for objective medical outcomes. With regard to objective outcomes, the treatment of rectal cancer often entails permanent biomedical ramifications, including chronic bowel, urinary, and sexual dysfunction (Vironen, Kairaluoma, Aalto, & Kellokumpu, 2006). In addition, appearance and function are both significantly altered for those patients who receive a permanent colostomy (Bleday & Garcia-Aguilar, 2007). Nevertheless, several reports indicate that mean HRQoL scores for rectal cancer survivors improve within 3-6 months post-surgery to the point that they are comparable to those reported in community studies (Camilleri-Brennan & Steele, 2001; Neuman et al., 2007; Rauch, Miny, Conroy, Neyton, & Guillemin, 2004). Also, there is no clear evidence that individuals with a colostomy have worse HRQoL than those without (Cornish et al., 2007; Pachler & Wille-Jorgensen, 2005). On the other hand, faecal incontinence and chronic diarrhoea have been shown to have a negative effect on certain domains of HRQoL, particularly social functioning (Vironen et al., 2006). But again, even though mean HRQoL among rectal cancer survivors is comparable to population controls, these distributions are usually skewed, with the long tail representing a great number of survivors reporting poor HRQoL (Camilleri-Brennan & Steele, 2002; Engel et al., 2003; Schmidt, Bestmann, Kuchler, Longo, & Kremer, 2005a, b). No previous studies that we could find have looked at the role of PTSD or PTSS in rectal cancer. In the present study, we wanted to investigate whether stable negative affective disposition is related to poor HRQoL or problems with PTSS. With the recent attention given to the specific role of anxiety in issues related to perceptions of health and illness (Cameron, 2003), we investigated longitudinally the relative influence of trait anxiety, demographic and medical variables on HRQoL and PTSS in a group of rectal cancer survivors. It was hypothesized that trait anxiety would predict self-reported HRQoL and PTSS, independent of other characteristics of the person or their disease.