Anxiety sensitivity in the prediction of pain-related fear and anxiety in a heterogeneous chronic pain population
Introduction
Anxiety sensitivity refers to the fear of anxiety-related symptoms that are based on beliefs that such sensations have negative somatic, social, or psychological consequences (Reiss & McNally, 1985). According to this perspective, anxiety sensitivity represents a stable psychological dimension that serves to amplify anxious and fearful responding to potentially anxiety-evoking stimuli (Taylor & Cox, 1998). For example, if a person perceives bodily sensations that are associated with autonomic arousal as a sign of imminent harm, this “high anxiety sensitive” individual will likely experience elevated levels of anxiety, and when lacking effective (emotion) regulatory strategies, be at an increased risk to panic (Zvolensky, Eifert, Lejuez & McNeil, 1999). Research indicates heightened anxiety sensitivity levels, as measured by the Anxiety Sensitivity Index (ASI; Reiss, Peterson, Gursky & McNally, 1986), longitudinally predict panic attacks in the natural environment (Schmidt, Lerew & Jackson, 1999) and elevated anxious responding in the laboratory (Zvolensky & Eifert, 2000).
There is a growing recognition that the ASI is hierarchical in structure, being comprised of three lower-order dimensions that all load on a single higher-order factor (Zinbarg, Mohlman & Hong, 1999). Across studies, it appears the three first-order factors measure fears of adverse physical outcomes (physical concerns), fears of cognitive dyscontrol (psychological concerns), and fears of the public display of anxiety symptoms (social concerns) (Stewart et al., 1997, Zinbarg et al., 1997). Furthermore, these first-order anxiety sensitivity factors appear to differentially predict anxious and fearful responding (Schmidt, 1999, Schmidt et al., 1999), and therefore may represent different psychological mechanisms for certain types of psychopathology (Cox, 1996). For example, researchers have found that the physical concerns dimension of the ASI best predicts anxiety-related responding to panic provocation relative to other ASI first-order factors (Eifert et al., 2000, Schmidt, 1999). These findings, in conjunction with related research (McNally & Eke, 1996), suggest that the higher the level of correspondence between the particular anxiety sensitivity domain and events that closely match that fear, the better anxious and fearful responding can be predicted.
Based largely upon such evidence, researchers increasingly are exploring the possibility that anxiety sensitivity may be a psychological risk factor for anxiety pathology (Eifert, Zvolensky & Lejuez, 2000; McNally, Hornig, Hoffman & Han, 1999), and most recently, chronic pain disorders (Asmundson & Taylor, 1996). Evidence linking anxiety sensitivity to chronic pain comes from a variety of sources. First, research indicates that there is a high degree of comorbidity between chronic pain problems and anxiety disorders, particularly individuals with interoceptive fears (Asmundson et al., 1996, Banks and Kearns, 1996). Second, individuals with chronic pain evidence high levels of somatic-related anxiety (Craig, 1994), and persons high in anxiety sensitivity often report elevated levels of persistent pain relative to comparison groups (Schmidt & Telch, 1997). Third, elevated levels of anxiety sensitivity may potentiate pain sensations when these individuals experience anxiety induced via laboratory stressors (Schmidt & Cook, 1999). Finally, anxiety sensitivity appears to exacerbate fears about pain after controlling for pain severity, promotes escape and avoidance of pain-related sensations, and may be related to maladaptive attentional processing of pain stimuli (Asmundson and Taylor, 1996, Asmundson et al., 1997). Taken together, anxiety sensitivity may reflect an individual difference dimension that increases risk for pain responding, particularly in anxiety-provoking contexts.
Asmundson (1999) recently hypothesized that anxiety sensitivity may increase the risk of developing high levels of fear of pain. Specifically, high anxiety sensitive individuals may be more likely to fear the consequences of pain sensations and therefore more apt to avoid them (e.g., restricting pain-inducing physical activities). Over time, such avoidance behavior may contribute to physical deconditioning, secondary behavioral problems (e.g., weight gain), and reduced social contact (McCracken, 1997). Furthermore, this pattern of responding is likely to be cyclical in nature, such that emotional responsivity and physical deconditioning lead to greater levels of pain, avoidance behavior, and reconfirms negative expectations about the pain experience. In this model, then, anxiety sensitivity represents a critical factor in the production and maintenance of chronic pain via its relation with the fear of and anxiety about pain.
Despite the theoretical promise of Asmundson’s conceptualization, researchers only have begun to systematically explore the relation between anxiety sensitivity and pain-related anxiety and fear. One of the primary reasons for this lack of investigation has been that although a wide variety of theoretical support and empirical evidence affirms the general importance of anxious and fearful responding about pain (e.g., Jensen, Turner & Romano, 1994), only recently have valid and reliable methodologies been developed to assess these distinct psychological constructs.
There exists a rich literature on the relation and distinction between anxiety and fear (e.g., Barlow, 1991, Rachman, 1991). Although it is beyond the scope of the present paper to identify each of the major points of agreement and disagreement among varying theoretical positions, it is increasingly apparent that there are both overlapping and distinctive features of these constructs. Zinbarg (1998), in a recent review of the literature, suggested the existing evidence indicates anxiety is primarily characterized by cognitive-affective responding that reflects both the preparation and inhibition of fear in the absence of a readily identifiable danger cue. Fear, in turn, reflects more of the visceral, mobilization for action (“fight-flight-freeze”) in response to identified danger. Thus, although anxiety and fear states can be characterized by collateral changes across behavioral systems, they differ in regard to the type, duration, and magnitude of response, as well as type of evoking stimuli (Eifert & Wilson, 1991). Accordingly, contemporary self-report assessment instruments for pain-related fear and anxiety measure, albeit imperfectly, these constructs.
By definition, fear of pain refers to a highly specific negative emotional reaction to particular pain-eliciting stimuli involving a high degree of mobilization for escape/avoidance behavior as well as visceral arousal and cognitive/affective distress (McNeil et al., 1999). To assess this construct, McNeil and Rainwater (1998) have developed the Fear of Pain Questionnaire-III (FPQ-III) that measures fears of severe pain, minor pain, and medical and dental pain. Research using this measure has found that high fear of pain individuals engage in more escape/avoidance behavior relative to persons with low fear of pain during acute pain induction, chronic pain patients report elevated levels of fear of severe pain relative to comparison groups, and the fear of pain (total score) uniquely predicts fear of specific events known to elicit pain and distress (Hursey and Jacks, 1992, McNeil and Rainwater, 1998, McNeil et al., 1999).
Pain-related anxiety is a closely related psychological construct that refers to prolonged cognitive, overt behavioral, and physiological responses to pain or pain-related events. In contrast to fear of pain, anxiety about pain typically involves more cognitive symptoms, less visceral activation and mobilization, and eliciting cues that are more diffuse (McNeil et al., 1994, Zinbarg, 1998). McCracken and colleagues have developed the Pain Anxiety Symptoms Scale (PASS) to assess four dimensions of pain-related anxiety, including pain-specific appraisals, cognitive symptoms, physiological symptoms, and escape and avoidance behavior (McCracken et al., 1992). Research using the PASS has found that patients with chronic pain disorders demonstrate greater pain-related anxiety relative to comparison groups, overpredict the intensity of pain, cope poorly with pain sensations, and evidence greater somatic reactivity in anticipation of pain-eliciting physical activity (McCracken, Gross, Sorg & Edmunds, 1993).
Although research generally has supported the potential role of anxiety sensitivity in the production of pain-related fear and anxiety (Asmundson, 1999), no direct tests have been completed using measures that assess these two constructs in a heterogeneous chronic pain population. Thus, it is unclear to what extent anxiety sensitivity uniquely predicts fear of and anxiety about pain. Toward this end, the present study was designed to evaluate anxiety sensitivity as a predictor of pain-related anxiety and fear relative to other theoretically-relevant variables of depression and pain severity. The second aim was to evaluate the differential predictions of particular anxiety sensitivity dimensions. It was hypothesized that anxiety sensitivity, as a global factor, would be a better predictor of pain-related anxiety and fear relative to the other independent variables. Additionally, it was hypothesized that the ASI physical concerns factor would be a better predictor of pain-related fear dimensions because they are characterized by high degrees of somatic arousal (i.e., physiological symptoms) and behavioral activation (i.e., escape behavior). In a related way, the ASI psychological concerns was hypothesized to be a better predictor of pain-related anxiety dimensions because they are characterized by greater levels of cognitive symptoms.
Section snippets
Participants
Participants included 68 consecutive physician referrals to the Pain Clinic in the Department of Anesthesiology at West Virginia University. There were 32 (47.1%) females and 36 (52.9%) males, ranging in age from 21 to 43 (M age=40.2, SD=8.8). All participants were Caucasian and had a prolonged history of chronic pain (M duration of pain chronicity=57.1 months, SD=55.1). The primary pain site for the participants was as follows: 52.5% (n=35) lower back, 13.2% (n=35) lower limbs, 11.8% (n=8)
Descriptive data and zero-order relations between predictor and criterion variables
Means and standard deviations for the independent and dependent variables are presented in Table 1. Overall, the scores for all measures are similar to those reported in other investigations studying individuals with chronic pain disorders (e.g., Asmundson et al., 1996, McCracken et al., 1993, McNeil and Rainwater, 1998).
We first computed zero-order correlations between the predictor variables and each of the dependent measures to determine the relation between these theoretically-relevant
Discussion
At a psychological level of analysis, persons with chronic pain problems often demonstrate heightened levels of pain-related anxiety and fear (Jensen et al., 1994). Increasingly, research indicates that such exaggerated psychological concerns may contribute to avoidance of pain-related events and activities, producing physical deconditioning and secondary behavioral problems (e.g., weight gain). Asmundson (1999) recently hypothesized that elevated anxiety sensitivity levels may increase the
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