Fear of Pain
Abstract and Keywords
Fear of pain is a construct that denotes both pain-related fear and pain-related anxiety. The construct and associated fear-anxiety-avoidance models have stimulated considerable research and the development of an effective treatment known as graded exposure in vivo. This chapter has several purposes. After providing a theoretical overview, descriptive and diagnostic issues pertinent to fear of pain are described. Several conceptual controversies are also discussed, including the differential role of fear and anxiety in pain-related avoidance, and whether fear of pain is best conceptualized as a simple phobia or a fundamental predilection to be fearful of anxiety symptoms. Assessment and treatment options for elevated fear of pain are described in detail and with reference to relevant empirical literature. The chapter concludes with suggested avenues for future research.
Current theory, based largely on elaboration of the Gate Control Theory of Pain (Melzack & Wall, 1965), holds that pain comprises sensory as well as cognitive, affective, behavioral, and social components (Bonica, 1990; Melzack & Wall, 1988). Thus, pain can be viewed as both a sensory and emotional experience. Pain is ubiquitous, typically occurring in response to actual or potential tissue damage as a motivator to withdraw from the source of pain and promote recuperative behavior. In the short-term, pain has survival value; however, when it becomes chronic (i.e., persists for 3 months or more) (International Association for the Study of Pain, 1986), it loses its adaptive qualities. Many people with chronic pain make frequent physician visits, sometimes undergo inappropriate medical evaluations, and often miss work and other important activities because of their symptoms (e.g., Spengler, Bigos, & Martin, 1986). They are also at increased risk for comorbid psychiatric conditions, particularly depression and anxiety disorders (e.g., Asmundson, Coons, Taylor, & Katz, 2002). Estimates from the United States indicate that 7% of the population has experienced chronic pain in the past 12 months (McWilliams, Cox, & Enns, 2003) at an annual cost exceeding $100 billion (Strassels, 2006; Weisberg & Vaillancourt, 1999).
Relative to the emotional context of pain, the constructs of fear and anxiety have recently garnered considerable theoretical, empirical, and practical attention. Observations regarding the relationship between fear, anxiety, and pain are, however, not new. More than 2,000 years ago Aristotle wrote, “Let fear, then, be a kind of pain or disturbance resulting from the imagination of impending danger, either destructive or painful.” Early empirical efforts revealed an association between pain and significant degrees of anxiety (Paulett, 1947; Rowbotham, 1946), viewing the latter as a product of intractable forms of the former. Rooted in these early observations, contemporary fear-anxiety-avoidance models (p. 552) of chronic pain are based primarily on the writings of several groups (Asmundson, Norton, & Norton, 1999; McCracken, Zayfert, & Gross, 1992; Vlaeyen, Kole-Snijders, Boeren, & van Eek, 1995; Waddell, Newton, Henderson, Sommerville, & Main, 1993). It is beyond the scope of this chapter to review the seminal works that provided the foundation on which the contemporary models are based, although comprehensive overviews are available (e.g., Asmundson, Norton, & Vlaeyen, 2004; Vlaeyen & Linton, 2000).
While each of the aforementioned groups of researchers has provided slightly different conceptualizations of the role of fear and anxiety in perpetuating pain (discussed in more detail below), the main ideas of each are captured in the model proposed by Vlaeyen and Linton 2000. This model (see Figure 1), focusing specifically on patients with idiopathic (i.e., in the absence of identifiable injury or organic pathology) chronic musculoskeletal pain but also applicable to those with other pain conditions, can be summarized as follows:
• When pain is perceived, a judgment of the meaning or purpose of the pain is placed on the experience (Pain Experience).
• For most people, pain is judged to be undesirable and unpleasant, but not catastrophic or suggestive of a major calamity (No Fear). Typically, the person engages in appropriate behavioral restriction followed by graduated increases in activity (Confrontation) until healing has occurred (Recovery).
• Conversely, for a significant minority of people, a catastrophic meaning is placed on the experience of pain (Pain Catastrophizing). Catastrophizing, influenced by predispositional and current psychological factors, leads to fear of pain (and/or reinjury) and thereafter spirals into a vicious and self-perpetuating cycle that promotes and maintains avoidance, activity limitations, disability, pain, catastrophizing, and so forth.
The fear-anxiety-avoidance models have garnered considerable empirical support, as evidenced (p. 553) by recent reviews (Asmundson et al., 1999; Vlaeyen & Linton, 2000) and an edited book on the topic (Asmundson, Vlaeyen, & Crombez, 2004), and have stimulated development and implementation of tailored assessment and treatment strategies.
Diagnostic and Descriptive Features
Pain can arise from physical injury, progression of disease, muscle tension, indigestion, eye strain, congested sinuses, menstruation, inactivity, and a wide array of other identifiable and unidentifiable sources. Most people do not become overly alarmed by pain; however, as noted above, for some it can provoke clinically significant and debilitating fear and anxiety. There is neither a current diagnostic entity nor are there diagnostic criteria for pathological levels of pain-related fear and anxiety. The DSM–IV–TR includes a diagnosis of Pain Disorder in its Somatoform Disorder section for which unspecified psychological factors (among other factors) are identified as diagnostic; yet, many researchers and clinicians who work with chronic pain patients find the DSM–IV–TR criteria for pain disorder to be problematic and of limited practical utility. These problems and limitations are succinctly outlined by Fishbain 1995 and Sharp 2004. Likewise, while conceptually similar to the DSM–IV–TR specific phobias (see below), this isnot typically a diagnosis that is applied in research or clinical practice to those with high pain-related fear and anxiety. Indeed, contrary to the DSM–IV–TR diagnostic criteria for specific phobia, most pain patients with high pain-related fear and anxiety are convinced that their fears, anxieties, and related avoidance behavior have a protective function and are in no way excessive or irrational (Vlaeyen, de Jong, Leeuw, & Crombez, 2004).
Fear of pain is a phrase used in the literature todescribe both pain-related fear and pain-related anxiety. Hereafter, we use the phrase fear of pain in reference to both of these constructs, except in instances where discussing important conceptual distinctions between fear and anxiety. The structure of fear of pain has been assumed to be multidimensional (i.e., comprising cognitive, behavioral, and physiological components) (McCracken, Zayfert, & Gross, 1993) and continuous (i.e., occurring along a continuum ranging from low to high) (Asmundson et al., 2004), and there is recent preliminary evidence from clinical samples to support this (Asmundson, Collimore, Bernstein, Zvolensky, Hadjistavropoulos, 2007). But, what constitutes high fear of pain? Various measures for assessing fear of pain exist (see “Assessment”). Space constraints do not permit a comprehensive review of the ways in which scores on each measure can be interpreted to inform the decision of whether an individual's fear of pain is high; however, for illustrative purposes we present how the 40-item Pain Anxiety Symptoms Scale (PASS) (McCracken et al., 1992) can be usedto make this determination.
The PASS is the most prominent fear of pain measure currently in use, with a total score ranging from 0 to 200. Although definitive cut-off scores for high fear of pain have yet to be established, precedent recommendations are available. High fear of pain has been defined by some researchers using PASS total scores between 94 and 100, or about the 50th percentile (de Gier, Peters, & Vlaeyen, 2003; Staats, Staats, & Hekmat, 2001). A brief review of research using the PASS suggests lower total scores may denote pathological fear of pain. Pooled means from studies with large samples (Hadjistavropoulos, Asmundson, & Kowalyk, 2004; Martin, Hadjistavropoulos, & McCreary, 2005; McCracken, Vowles, & Eccleston, 2005; McCracken et al., 1993; Roelofs et al., 2004) indicate chronic pain patients report higher PASS total scores (M = 76.68, SD = 20.85) than studies evaluating pain-free control participants (M = 59.37, SD = 18.89), t (1726) = 17.70, p 〈.001, r2 =.15) (Asmundson, Wright, & Hadjistavropoulos, 2005; Muris, Vlaeyen, & Meesters, 2001; Osman, Barrios, Osman, Schneekloth, & Troutman, 1994; Roelofs, Peters, Deutz, Spijker, & Vlaeyen, 2005). Given that approximately 30% of patients with chronic pain have high fear of pain (Asmundson, Norton, & Allerdings, 1997), a PASS total score of approximately 85 (i.e., pooled sample M plus.5 SD) may represent an optimal cut-off, at least in clinical samples. Future efforts to determine definitive cut-off scores for clinical and nonclinical samples using empirical methods are needed to further facilitate identification of, and treatment planning for, pathological fear of pain.
There is an implicit presupposition in some iterations of the contemporary fear-anxiety-avoidance models that a direct link exists from fear of pain to avoidance behavior when, in fact, anxiety serves as an important intervening variable. To account for this, Asmundson et al. 2004 have proposed a revised model (see Figure 2) wherein catastrophic (mis)interpretation produces a fear-based emotional stsate designed to protect against perceived (p. 554) (p. 555) pain-related threat (i.e., fear of pain) by motivating escape behaviors and, in some cases, promoting the onset of anxiety. In this model it is anxiety regarding future encounters with pain-related threat that is most important to the development and maintenance of chronicity because it promotes avoidance and other preventative behaviors. Further empirical scrutiny of the distinction between pain-related fear and anxiety and the potentially divergent implications of these constructs for maintaining pain and disability over time is needed.
There are also different views regarding the nature of fear of pain. One view is that fear of pain is similar in many ways to specific phobias (e.g., fear of spiders), wherein fear of nociception (i.e., pain sensations) arising from work or leisure activity is at the root of avoidance and other negative pain-related behaviors. Within this general view there are differing amounts of emphasis on whether the fear is of painful sensations per se (Letham, Slade, Troup, & Bentley, 1983; Vlaeyen & Linton, 2000), the activities that are associated with those sensations (e.g., Waddell et al., 1993), or of painful reinjury (Kori, Miller, & Todd, 1990). Another view is that fear of pain is a manifestation of a fundamental predilection to be generally fearful of anything that produces anxiety symptoms, including pain and its consequences; that is, fear of pain is believed to be a manifestation of anxiety sensitivity (Asmundson et al., 1999; Greenberg & Burns, 2003). Most recently it has been suggested that fear of pain may be a manifestation of a more general predilection to appraisals of illness and injury as indicative of catastrophe (e.g., see Carleton, Asmundson, & Taylor, 2005; Carleton, Park, & Asmundson, 2006; Vancleef, Peters, Roelofs, & Asmundson, 2006).
These conceptual distinctions are particularly important to understanding the mechanisms that underlie the experience and maintenance of idiopathic chronic pain and ongoing pain-related disability. Consequently, they warrant attention in future empirical efforts. They also need to be taken into consideration during assessment and treatment planning.
Assessment Rationale and Targets
There are three important first steps in the assessment of a patient with high fear of pain. First, it is critical to rule out existing medical conditions that might account for complaints of pain and functional limitations. Why? It is necessary to determine whether empirically supported treatments for fear of pain, comprising varying combinations of cognitive and behavioral strategies involving exposure to feared sensations and activities, are indicated. To illustrate, the approach to treating a person with a ruptured intervertebral spinal disc—causing back pain, leg pain, and weakness of the lower extremity muscles—accompanied by high fear of pain would be substantially different from the graded exposure in vivo approach (see below) that might be used for a person with idiopathic low back pain and high fear of pain.
Second, it is necessary to clearly identify the object of fear and anxiety—whether it is actual pain sensations, certain activities that are associated with pain or injury, bodily sensations (mis)interpreted as signs of disease, concerns regarding abilities to pay bills or remain active in professional and leisure pursuits, and so forth. This may sound like a simpler task than it is. Many patients will be reluctant to accept that their pain and functional limitations have anything to do with fear or anxiety, instead attributing them to a physical cause. Most will fear pain sensations, but some may not. Instead, their fear may be more specifically related to the consequences associated with pain, such as permanent disability. In many cases there may be more than one object that warrants consideration in treatment.
Finally, it is necessary to determine why a patient is seeking treatment. Some patients present for treatment not because they believe it will help but, instead, because they have been pressured to do so by their doctor, family, or friends. If not identified and addressed (e.g., by motivational interviewing strategies; see Taylor & Asmundson, 2004), these negative beliefs can interfere with treatment adherence and outcome.
There are several assessment methods that are useful in treatment planning for patients with high fear of pain, including self-report, observation (e.g., of facial expressions, protective behaviors, avoidance behaviors), and physiological monitoring (e.g., of heart rate variability, magnitude of startle in response to potentially threatening stimuli). Despite theoretical importance (e.g., Norton & Asmundson, 2003) and practical utility (e.g., Hadjistavropoulos & Craig, 2002) of the observational and physiological methods, it is self-report that is the most often used method for assessing fear of pain. We refer the interested reader to McNeil and Vowles (2004) for further details regarding the observational and (p. 556) physiological monitoring methods. Below we summarize the most often used self-report measures of fear of pain and provide a brief overview of semistructured interview techniques.
Pain Anxiety Symptoms Scale (PASS) (McCracken et al., 1992). The PASS is, as noted above, the most prominent of the fear of pain measures. It comprises 40 items distributed equally on four 10-item subscales that measure factorially distinct dimensions of fear of pain, including cognitive interference related to pain, fearful appraisals of pain, escape and avoidance behavior in response to activities associated with pain, and physiological symptoms arising from pain (Larsen et al., 1997; McCracken et al., 1992; Osman et al., 1994). Each item (e.g., Pain seems to cause my heart to pound or race) is responded to usinga 6-point scale anchored from 0 (never) to 5 (always). The PASS has demonstrated good to excellent reliability and validity (McCracken & Gross, 1995). The PASS total score is positively correlated with general anxiety, pain, and self-reported disability (Crombez, Vlaeyen, Heuts, & Lysens, 1999; McCracken & Gross, 1995), nonspecific physical complaints (McCracken, Faber, & Janeck, 1998), and physical capacity (Burns, Mullen, Higdon, Wei, & Lansky, 2000).
Fear of Pain Questionnaire-III (FPQ-III) (McNeil & Rainwater, 1998). The FPQ-III is a 30-item measure intended to assess fears about pain in relation to specific pain-causing stimuli. Each item is responded to using a 5-point Likert scale ranging from 1 (not at all) to 5 (extreme). The FPQ-III consists of three factorially distinct subscales, each related to a specific type of pain: Severe pain (e.g., having someone slam a heavy car door on your hand), minor pain (e.g., biting your tongue while eating), and medical pain (e.g., having one of your teeth drilled). Recent confirmatoryfactor analyses support the three-factor structure (Albaret, Sastre, Cottensin, & Mullet, 2004), and there is evidence of good test-retest reliability and internal consistency (McNeil & Rainwater, 1998; Osman, Breitenstein, Barrios, Gutierrez, & Kopper, 2001). Correlational analyses indicate that the FPQ-III is moderately positively associated with the PASS (r =.45; Osman et al., 2001), suggesting that these measures may be assessing distinct (e.g., situational versus trait) fear-based constructs.
Fear-Avoidance Beliefs Questionnaire (FABQ) (Waddell et al., 1993). The FABQ is a 16-item measure assessing pain-related beliefs about possible harm from physical activities. Each item (e.g., Physical activity might harm my back) is responded to using a 5-point Likert scale ranging from 0 (completely disagree) to 6 (completely agree). There are two factorially distinct subscales, one focusing on work-related beliefs and the other on physical activity beliefs. The FABQ and its subscales have good validity, reliability, and internal consistency (Crombez et al., 1999; Waddell et al., 1993). Waddell et al. 1993 reported that the subscale scores are moderately related to pain intensity and, even after controlling for pain intensity, that the work-related beliefs subscale is strongly correlated with measures of disability and work loss.
Tampa Scale of Kinesiophobia (TSK) (Kori et al., 1990). The TSK is a 17-item measure designed to tap fears of movement (i.e., kinesiophobia) based on a perceived vulnerability to pain or reinjury. Each item (e.g., Pain always means I have injured my body) is responded to using a 4-point Likertscale ranging from 1 (strongly disagree) to 4 (strongly agree). Factor analyses suggest a two-factor model, measuring harm and fear avoidance, respectively (Goubert et al., 2004; Swinkels-Meewisse, Roelofs, Verbeek, Oostendorp, & Vlaeyen, 2003). The TSK has good reliability and validity (Swinkels-Meewisse et al., 2003; Vlaeyen et al., 1995). The TSK total score is positively correlated with self-reported disability and negatively correlated with performance on a back flexion and extension task (Crombez et al., 1999).
Anxiety Sensitivity Index (ASI) (Peterson & Reiss,1992). The ASI is a 16-item measure designed to assess fear of anxiety signs and symptoms based on the belief that they may have harmful consequences. Each item (e.g., Unusual body sensations scare me) is responded to using a 5-point Likert scale ranging from 0 (agree very little) to 4 (agree very much). The ASI has good validity, reliability, and internal consistency (Deacon & Valentiner, 2001; Peterson & Reiss, 1992) and has been shown to be conceptually distinct from trait anxiety (McNally, 1996). It is associated with, and predictive of, fear of pain (Asmundson & Norton, 1995; Asmundson & Taylor, 1996; Greenberg & Burns, 2003). These and other recent findings (Zvolensky, Goodie, McNeil, Sperry, & Sorrell, 2001) support the view that fear of pain may be a manifestation of anxiety sensitivity (Carleton, Asmundson, Collimore, & Ellwanger, 2006).
Other Self-Report Measures. There are other measures (see McNeil & Vowles, 2004) that can be used to assess fear of pain. Short forms for several of the aforementioned measures have also been created. These include the PASS-20 (McCracken & Dhingra, 2002) and a 13-item TSK (p. 557) (Clark, Kori, & Brockel, 1996). Finally, related measures, such as the Pain Catastrophizing Scale (PCS) (Sullivan, Bishop, & Pivik, 1995) and the revised Illness/ Injury Sensitivity Index (ISI-R) (Carleton, Park, et al., 2006), also warrant consideration when assessing patients with pain-related fear and anxiety.
Semistructured Interviews. Use of semistructuredinterview can provide a wealth of information regarding origins of fear of pain, its impact on current beliefs and assumptions, its impact on behavior, as well as ancillary complications (e.g., marital conflict, depression). Therapist-guided inquiries that purposefully avoid direct mention of pain-related fear and anxiety (e.g., What do you think is the cause of your pain? Why do you think __ might further harm your back? If the pain is left untreated, what do you think will happen?) mayfacilitate identification of the patient's conceptualization of his or her problem. Specific questions (e.g., What makes your pain worse? What activities does pain stop you from doing?) can provide invaluable information regarding pain triggers, patterns of avoidance, and the patient's treatment goals (Vlaeyen et al., 2004). The information derived from these questions can also be used in conjunction with the Photograph Series of Daily Activities (PHODA) (Kugler, Wijn, Geilen, de Jong, & Vlaeyen, 1999)—a series of 98 photographs depicting various activities and movements of daily life—for developing a hierarchy of the patient's pain-related fears and anxieties.
Description of Treatments
The development of chronic pain treatments that focus on the emotional aspects of pain is increasingly pertinent. Indeed, recent review of physical treatments of chronic musculoskeletal pain concluded that, though potentially therapeutic, there is little empirical evidence supporting their effectiveness (Wright & Sluka, 2001). In contrast, a recent meta-analysis (Morley, Eccleston, & Williams, 1999) of randomized controlled trials of cognitive behavior therapy (CBT) for the treatment of chronic pain (excluding headache) concluded that CBT, compared to other treatments and a waitlist control, produced significantly greater improvements in pain, pain behavior, activity levels, affect, and ability to cope effectively. Thus, CBT appears to be an effective treatment for chronic pain. The specific application of CBT for reduction of pain-related fear and anxiety is still in its infancy but is, nonetheless, very promising.
Features of Treatment
There are several approaches—each with varying degrees of empirical support—that we recommend for treating a patient with idiopathic chronic pain accompanied by pain-related fear and anxiety. The first is a variant on CBT for health anxiety as described in Chapter 40 (also see Taylor & Asmundson, 2004). This empirically supported approach can be particularly effective in cases where the patient (mis)interprets pain sensations as being symptomatic of an underlying disease state and is more fearful of the disease and its consequences than of the pain per se. The second, based on the view that fear of pain is a manifestation of anxiety sensitivity, is the application of exposure to anxiety-provoking bodily sensations (i.e., interoceptive exposure); however, while empirically supported for panic and other anxiety disorders (see Taylor, 2000), this approach remains to be systematically evaluated in the context of fear of pain and is not further discussed here. The third, rooted in observed similarities in behavior between chronic pain patients with high fear of pain and patients with specific phobias and various other anxiety disorders, involves the application of graded exposure in vivo. This approach is well suited for patients who avoid activities based on the belief that being active will provoke further pain and, possibly, reinjury. The components and process of this approach are outlined below. More detailed explanations are available elsewhere (e.g., see Vlaeyen et al., 2004).
• Assessment is conducted as described earlier. Care should be taken to facilitate the development of a strong therapeutic relationship (for suggestions specific to patients with high fear of pain, see Hadjistavropoulos & Kowalyk, 2004).
• Psychoeducation is used to help the patient reformulate his or her view of pain as a signal of impending catastrophe (e.g., permanent disability, disease, reinjury) to one of pain as a common experience that can be self-managed. This is accomplished through careful explanation of the fear-anxiety-avoidance model using simplified versions of Figures 1 and 2, adapted to the specific characteristics of the patient's presenting symptoms, behaviors, and beliefs. Appreciation of the premise that hurt does not always equal harm, along with a basic understanding of the typical course of pain (and, if appropriate, healing), can ameliorate fear of pain and thereby encourage activity participation.
(p. 558) • Exposure is based on an individualized hierarchy that begins with activities rated as minimally fear-and anxiety-rovoking to those rated as highly fear-and anxiety-provoking. The hierarchy can be derived using ratings of movements and activities from the PHODA.
• After obtaining the patient's agreement to perform certain movements and activities, the therapist models each activity in order to demonstrate the correct ergonomic method of performance and to clearly illustrate that he or she does not find it to be threatening. The therapist may also provide assistance as the patient begins performing the activity; however, to promote independence (and reduce probability of becoming a safety signal), the therapist should gradually withdraw from assisting as therapy progresses.
• Prior to each exposure, current and expected levels of pain and anxiety about performing the movement or activity are rated. Ten point visual analog scales, with 0 = no pain/anxiety and 10 = most pain/anxiety possible, are useful for thispurpose. Following each exposure, levels of actual pain and anxiety are rated on similar 10-point scales. This information can be used to monitor and illustrate for the patient changes in pain and anxiety across repeated exposures and tasks.
• Behavioral tests are performed for each movement and activity on the hierarchy in order to challenge expectations (e.g., I am going to be severely reinjured if I attempt this activity) andprovide evidence for alternatives (e.g., I can do this activity without harming myself). Patients repetitively perform each movement or activity, working their way up the hierarchy as expectations that it is harmful are disconfirmed.
• Exposure exercises are conducted first within treatment sessions under therapist supervision and thereafter as homework assignments to promote independence. The number and duration of treatment sessions reported in the literature varies considerably, ranging from as many as 30 1.5 hour sessions delivered 3 times per week to as few as eight 40 minute sessions delivered 2 times per week.
Narrative Overview of Empirical Findings of Graded Exposure in Vivo
Uncontrolled trials indicate that graded exposure in vivo is successful in reducing fear of pain as well as pain severity. To illustrate, Vlaeyen, de Jong, Geilen, Heuts, and van Breukelen (2001) randomly assigned four individuals with high scores on the TSK to receive graded exposure in vivo followed by graded activity (i.e., graduated increases in general activity levels despite pain), or the same treatments in reverse order. Fear of pain, catastrophizing, perceived life control, and functional disability were measured before and after the treatment, with pain-related fearful appraisals assessed daily (using 11 questions adapted from the PASS, TSK, and PCS). A time-series analysis of the daily measures revealed that pain-related fearful appraisals reduced only with the graded exposure in vivo, and not with graded activity, regardless of the treatment order. Furthermore, pre-to posttreatment analysis demonstrated that reductions in pain-related fear corresponded with increases in function and were followed by reductions in pain intensity. These findings have subsequently been replicated in a number of case studies of patients with chronic musculoskeletal pain (Boersma et al., 2004; Linton, Overmeer, Janson, Vlaeyen, & de Jong, 2002; Vlaeyen, de Jong, Onghena, Kerckhoffs-Hanssen, & Kole-Snijders, 2002) and complex regional pain syndrome (de Jong et al., 2005). More recently, Woods and Asmundson 2008 completed the first randomized controlled trial, comparing 15 patients receiving graded exposure in vivo to 13 patients receiving graded activity and 16 patients placed on a waitlist. All patients had idiopathic chronic low back pain. Results indicated significantly greater pre-to posttreatment reductions in fear of pain and self-reported disability for patients receiving graded exposure in vivo compared to those in the other conditions. These results, while encouraging, warrant replication.
Outstanding Issues and Conclusion
The fear of pain concept and associated fear-anxiety-avoidance models of chronic pain have stimulated considerable amounts or research over the past two decades and, importantly, have stimulated the development of effective treatments for pain conditions associated with high personal and social costs. Notwithstanding, there are numerous questions that require further conceptual development and empirical evaluation. For example, is fear of pain best conceptualized as a continuous entity and, if so, at what point does it become maladaptive? Or, is fear of pain taxonic, having normative and pathological forms that are qualitatively distinct? Are pain sensations the primary object of fear of pain? Or, is fear of pain a manifestation of a more fundamental fear, perhaps of anxiety symptoms or of disease? Do these differing views hold important implications for effective (p. 559) intervention? What are the basic emotional, environmental, cultural, biological, and genetic influences on fear of pain? Are the subtle nuances between pain-related fear and pain-related anxiety important to assessment and treatment planning? Is graded exposure in vivo the most effective treatment, or are there equally effective pharmacological and psychosocial interventions? For what pain conditions are these interventions indicated? Evidence-based answers to these questions will aid in refining the currently promising interventions that are available to therapists treating chronic pain patients with high fear of pain.
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