How does persistent pain develop? An analysis of the relationship between psychological variables, pain and function across stages of chronicity

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Abstract

The fear-avoidance model is an attempt to underscore the importance of cognitive and behavioral factors, in a chain of events linking pain to disability. However, it is not clear at what time point the psychological variables within the model begin to be prominent. The aim of this study was to investigate the role of these psychological variables in the development of a chronic musculoskeletal pain problem. Three stages of chronicity, defined by duration of pain, provided a proxy for the developmental process: <1 year (N=48), 1–3 years (N=47) and >3 years (N=89). Subjects completed questionnaires on fear of movement, catastrophizing, depression, pain and function. The results indicate that the relationship between fear of movement and function is moderated by the stage of chronicity. Regression analyses showed that fear of movement did not explain any variance in the group with pain duration <1 year. Fear of movement did explain variance in the groups with pain duration of 1–3 years and >3 years. This suggests that the time point in the development of a musculoskeletal pain problem might be an essential aspect of the importance of the relationship between psychological components and function.

Introduction

Spinal pain is a common problem in modern day society; approximately 85% of the population suffers from it, at some time point in life. Where most people recover quick and without further action necessary, an estimated 3–10% continue to develop a long-term (work) disability (Reid, Haugh, Hazard, & Tripathi, 1997). These people consume an enormous amount of resources (Nachemson & Jonsson, 2000).

Although several psychological risk factors have been established for the development of chronic pain and disability, relatively little is known about the developmental process that catalyzes acute pain into a chronic pain problem (Linton, 2002). The fear-avoidance model offers one possible mechanism of how the development from acute pain to chronic pain disability might unfold (Lethem, Slade, Troup, & Bentley, 1983; Vlaeyen, Kole-Snijders, Boeren, & van Eek, 1995a). This model underscores the importance of cognitive and behavioral factors, in a chain of events linking the experience of pain to disability. The fear-avoidance model stresses the role of catastrophic interpretations following a pain experience, and subsequent fear and hypervigilance. The other prominent role is given to avoidance of activity, largely fueled by the fear that physical activity will cause harm and will worsen the pain problem (Vlaeyen & Linton, 2000).

Research supports that fear-avoidance beliefs are related to chronic pain and disability. For example, experimental evidence suggests that chronic back pain patients overpredict the pain a back-stressing movement will produce and that this overprediction is related to fear of (re)injury (Crombez, Vervaet, Lysens, Eelen, & Baeyens, 1996; Goubert, Francken, Crombez, Vansteenwegen, & Lysens, 2002). Further, cross-sectional studies show that there is a strong relationship between pain-related fear and disability in chronic pain patients (Vlaeyen, Kole-Snijders, Boeren et al., 1995a; Vlaeyen, Kole-Snijders, Rotteveel, Ruesink, & Heuts, 1995b; Crombez, Vlaeyen, Heuts, & Lysens, 1999).

Evidence suggests that pain-related fear is present at a very early stage. For example, prospective studies show that pain-related fear is a significant predictor of future disability in patients suffering from an acute episode of low back pain (Klenerman et al., 1995; Fritz & George, 2002). Moreover, fear-avoidance beliefs and catastrophizing are reported to occur in moderate levels in the general population and can increase the risk for a new episode of back pain (Buer & Linton, 2002). Likewise, another study of the general population shows that, for people with low back pain at baseline, high levels of catastrophizing and fear-avoidance beliefs predict low back pain with disability at a 6-month follow up (Picavet, Vlaeyen, & Schouten, 2002). Thus, fear-avoidance beliefs and catastrophizing occur both in pain-free, non-chronic and chronic populations and are risk factors for future disability.

It is proposed that the development of a chronic pain problem involves an interaction between the injury, the experience of pain, and psychological factors such as somatic anxiety and fear-avoidance, but that it is unclear when and how these aspects begin to be prominent (Linton (1999), Linton (2000)). Consequently, there is a need to study the relationship between psychological factors and dysfunction in relation to the development of a chronic pain problem. One approach might be to use cross-sectional comparisons where different stages of chronicity provide a proxy for the developmental process. An example is the study by Sullivan et al. (Sullivan, Sullivan, & Adams, 2002) where a unique relationship between catastrophizing and dysfunction only emerged for patients with pain durations of more than 2 years. Thus, such a comparative approach might give the opportunity to begin to untangle the relationship between key psychological variables and dysfunction in the development of chronic pain disability.

The aim of this study was to understand the role of fear-avoidance in the development of a chronic pain problem. To accomplish this we selected people at different stages of chronicity and divided them into three groups with increasing durations of spinal pain. We focused on variables that are incorporated in the fear-avoidance model: pain intensity, function and the psychological variables: fear-avoidance beliefs, catastrophizing and depression. The specific objectives of this investigation were:

  • 1.

    To describe and examine the differences between people at three stages in the development of a chronic pain problem.

  • 2.

    To investigate the interrelationships between pain intensity, psychological variables and function across three stages in the development of a chronic pain problem. It is hypothesized that stage of chronicity moderates the effect of the psychological variables on function.

Section snippets

Overview of the study

This investigation employed a cross-sectional design and compared subjects at different stages in the development of a pain problem ranging from a relatively early pain problem to a long-term pain problem. Subjects were recruited from the general community to increase the likelihood of variation in pain duration, pain characteristics and functional difficulties. All subjects completed a battery of questionnaires with emphasis on aspects incorporated in the fear-avoidance model: pain intensity,

Examination of differences across the stages of chronicity

Table 1 shows background and pain characteristics of the participants, according to their level of chronicity. There was a significant overall difference between the groups on the pain variables (Wilks’ Lambda F (6, 354)=2.93, p=0.008). Specifically, participants with pain duration >3 years reported significantly higher levels of current pain intensity and had pain more frequently than participants with pain duration <1 year. There were no significant differences on any of the pain variables

Discussion

The aim of this study was to understand the role of fear-avoidance in the development of chronic pain and disability. We divided people into three groups with increasing pain duration, mimicking different stages in the development of a spinal pain problem. The groups showed distinct profiles with regard to pain and function suggesting that they are distinct and may represent different developmental stages. It was hypothesized that the relationship between the psychological variables within the

Acknowledgements

This study was supported by grants from Trygg-Hansa Research Foundation and the Örebro County Council, Sweden. We are grateful to Johan Vlaeyen for valuable comments on the manuscript and to Cecilia Fedeli and Ing-Liss Bryngelsson for statistical advice and assistance.

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