Graded exposure in vivo in the treatment of pain-related fear: a replicated single-case experimental design in four patients with chronic low back pain
Introduction
Chronic low back pain is a major health and economical problem in Western industrialised countries. Back pain has become one of the most common reasons for work loss, health care use and sickness benefits (Waddell, 1998). For example, Van Tulder, Koes and Bouter (1995) estimated the total direct medical costs of back pain in the Netherlands in 1991 at US$ 367.6 million and the total indirect costs for the entire labour force at US$ 4.6 billion. From a traditional disease model, pain disability is merely the result of an underlying physical pathology that can be located and cured. However, in the majority of patients who are disabled because of back pain, no structural lesions can be identified and diagnostic abnormalities have also been found in symptom-free people (Jensen et al., 1994).
In a quite different attempt to explain how and why some individuals with musculoskeletal pain develop a chronic pain syndrome, biopsychosocial models have been developed including the “fear-avoidance model of exaggerated pain perception” (Lethem, Slade, Troup & Bentley, 1983) and more recently, a cognitive model of fear of movement/(re)injury (Vlaeyen, Kole-Snijders, Boeren & van Eek, 1995a). The central concept of these models is fear of pain, or the more specific fear that physical activity will cause (re)injury. Two opposing behavioural responses to these fears are postulated: ‘confrontation’ and ‘avoidance’. If no serious somatic pathology can be identified in patients with back pain, confrontation with daily activities despite pain is conceptualised as an adaptive response that eventually may lead to the reduction of fear and the promotion of recovery. In contrast, avoidance leads to the maintenance or exacerbation of fear, possibly resulting in condition comparable to a phobia. The avoidance results in the reduction of both social and physical activities, which in turn leads to a number of physical and psychological consequences augmenting the disability (Philips, 1987). Prospective studies in acute low back pain patients (Klenerman et al., 1995) and healthy people (Linton, Buer, Vlaeyen & Hellsing, 2000) have provided support for the idea that pain-related fear may be an important precursor of pain disability.
Kori, Miller and Todd (1990) introduced the term ‘kinesiophobia’ (kinesis=movement) for the condition in which a patient has “an excessive, irrational and debilitating fear of physical movement and activity resulting from a feeling of vulnerability to painful injury or reinjury”. These authors also developed the Tampa Scale for Kinesiophobia (TSK) as a measure for fear of movement/(re)injury. Recent evidence revealed that during confrontation with feared movements, chronic low back pain patients, who are fearful of movement/(re)injury, typically show increased muscular reactivity (Vlaeyen et al., 1999), escape and avoidance responses (Crombez, Vervaet, Lysens, Eelen & Baeyens, 1996; Crombez, Vlaeyen, Heuts & Lysens, 1999; Vlaeyen et al., 1995a; Vlaeyen, Kole-Snijders, Rotteveel, Ruesink & Heuts, 1995b) and pain-specific worries such as pain catastrophising (McCracken & Gross, 1993), rendering support for the idea that chronic pain and chronic fear share important characteristics (Asmundson et al., 1999, Philips, 1987, Vlaeyen and Linton, 2000).
What are the clinical implications of these findings? Philips (1987) was one of the first to argue for the systematic application of graded exposure in order to produce disconfirmations between expectations of pain and harm, the actual pain and other consequences of the activity. Experimental support for this idea is provided by the match/mismatch model of pain (Rachman & Arntz, 1991) which states that people initially tend to overpredict how much pain they will experience, but after some exposures these predictions tend to be corrected to match with the actual experience. A similar pattern was found by Crombez, Vervaet, Lysens, Eelen and Baeyens (1996) in a sample of chronic low back pain patients who were requested to perform four exercise bouts at maximal force. As predicted, the chronic low back pain patients initially overpredicted pain, but after repetition of the exercise bout the overprediction was readily corrected. In sum, it is quite plausible that, in analogy with the treatment of phobias, graded exposure to back-stressing movements may indeed be a successful treatment approach for back pain patients reporting substantial fear of movement/(re)injury. However, no clinical outcome studies of this kind have been reported in the literature.
The aim of the current study was to follow up on the early suggestions made by Philips (1987) and to explore the effects of graded exposure in vivo in four chronic low back pain patients with substantial fear of movement/(re)injury. Using a replicated single-case cross-over experimental design, graded exposure in vivo is contrasted with a usual graded activity program.
Section snippets
Treatments
Two treatments were contrasted; (A) a cognitive-behavioural graded exposure in vivo (GEXP) and (B) a graded activity treatment (GA). Both treatments were imbedded in a comprehensive behavioural rehabilitation program provided by an interdisciplinary treatment staff of the department of Pain Rehabilitation of the Hoensbroeck Rehabilitation Centre. This program generally follows the operant treatment principles and includes graded activity, pacing techniques, relaxation and group education about
Manipulation check
Fig. 1shows the patterns of daily VAS ratings for fear of movement/(re)injury. Visual inspection reveals that trend changes only occur when GEXP follows either baseline or GACT, but not at the other transitions (baseline-GACT, GEXP-GACT). This pattern suggests that pain-related fear is only reduced by the GEXP. Similar results were found for the variables fear of pain and pain catastrophising. The results of the time series analysis according to the AR1 procedure are displayed in Table 2and
Discussion
The aim of this study was to examine the effectiveness of a cognitive-behavioural graded exposure in vivo treatment as compared to graded activity in reducing pain-related fears, pain catastrophising and pain disability in CLBP patients reporting substantial fear of movement/(re)injury. Four consecutive CLBP patients who were referred for outpatient behavioural rehabilitation and who met the study criteria, including the report of substantial fear of movement/(re)injury were included. A single
Acknowledgements
The authors wish to thank Geert Crombez and Robert Wagenaar for their helpful suggestions throughout the study. Herman Mulder, Noel Dortu and the staff of the Department of Pain Rehabilitation of the Hoensbroeck Rehabilitation Centre are acknowledged for their contribution in the clinical management of the patients. We are grateful to Arnoud Arntz, Mike Nicholas and Marcel van den Hout for their helpful comments on an earlier version of this manuscript. This study is supported by Grant No.
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