Review article
Fear-avoidance and its consequences in chronic musculoskeletal pain:
a state of the art
Johan W.S. Vlaeyen
a,b,
*
, Steven J. Linton
c
a
Department of Medical, Clinical and Experimental Psychology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
b
Institute for Rehabilitation Research, Behavioral Rehabilitation Research Program, P.O. Box 192, 6400 AD Hoensbroek, The Netherlands
c
Department of Occupational and Environmental Medicine, O
È
rebro Medical Center Hospital, 701-85 O
È
rebro, Sweden
Received 3 November 1998; received in revised form 8 September 1999; accepted 9 September 1999
Abstract
In an attempt to explain how and why some individuals with musculoskeletal pain develop a chronic pain syndrome, Lethem et al. (Lethem
J, Slade PD, Troup JDG, Bentley G. Outline of a fear-avoidance model of exaggerated pain perceptions. Behav Res Ther 1983;21:401±408)
introduced a so-called `fear-avoidance' model. The central concept of their model is fear of pain. `Confrontation' and `avoidance' are
postulated as the two extreme responses to this fear, of which the former leads to the reduction of fear over time. The latter, however, leads to
the maintenance or exacerbation of fear, possibly generating a phobic state. In the last decade, an increasing number of investigations have
corroborated and re®ned the fear-avoidance model. The aim of this paper is to review the existing evidence for the mediating role of pain-
related fear, and its immediate and long-term consequences in the initiation and maintenance of chronic pain disability. We ®rst highlight
possible precursors of pain-related fear including the role negative appraisal of internal and external stimuli, negative affectivity and anxiety
sensitivity may play. Subsequently, a number of fear-related processes will be discussed including escape and avoidance behaviors resulting
in poor behavioral performance, hypervigilance to internal and external illness information, muscular reactivity, and physical disuse in terms
of deconditioning and guarded movement. We also review the available assessment methods for the quanti®cation of pain-related fear and
avoidance. Finally, we discuss the implications of the recent ®ndings for the prevention and treatment of chronic musculoskeletal pain.
Although there are still a number of unresolved issues which merit future research attention, pain-related fear and avoidance appear to be an
essential feature of the development of a chronic problem for a substantial number of patients with musculoskeletal pain. q 2000 Interna-
tional Association for the Study of Pain. Published by Elsevier Science B.V. All rights reserved.
Keywords: Pain-related fear; Chronic pain; Musculoskeletal pain; Avoidance; Disability
1. Introduction
The development of chronic musculoskeletal pain from
an apparently `healed' acute injury has baf¯ed researchers
and clinicians alike. The fear-avoidance model has recently
provided an enticing account of how chronic pain may
develop. Pain problems have been viewed as complex,
multidimensional developmental processes where various
psychosocial factors are of the utmost importance (Skeving-
ton, 1995; Gatchel and Turk, 1996). However, it has been
dif®cult to speci®cally spell-out the mechanisms by which
acute problems become chronic. Thus, the introduction of
the so-called `fear-avoidance' model has been a welcomed
explanation.
Fear-avoidance, which refers to the avoidance of move-
ments or activities based on fear, has been put forth as a
central mechanism in the development of long-term back
pain problems. In particular, fear-avoidance is thought to
play an instrumental role in the so-called deconditioning
syndrome. Screening and assessment measures have
begun to appear, and treatment as well as preventive inter-
ventions have been designed that are congruent with the
fear-avoidance concept. Some authors have gone so far as
to term the phenomenon an irrational fear or phobia, as the
source of the danger is often not recognized by the clinician
(Kori et al., 1990). However, research on fear-avoidance is
very broad and ranges from theoretical analyses to labora-
tory and clinical studies. In the last decade, an increasing
number of both experimental and clinical studies have
shown that fear and anxiety in¯uence the experience of
pain, and chronic pain disability in particular. Moreover,
the concept involves behavioral, physiological, and cogni-
tive aspects of learning. Although a good deal of research
has been conducted, it appears to have gaps, especially with
Pain 85 (2000) 317±332
0304-3959/00/$20.00 q 2000 International Association for the Study of Pain. Published by Elsevier Science B.V. All rights reserved.
PII: S0304-3959(99)00242-0
www.elsevier.nl/locate/pain
* Corresponding author.
E-mail address: j.vlaeyen@dep.unimaas.nl (J.W.S. Vlaeyen)
regard to its application in the ®eld of chronic pain. Conse-
quently, there is a need for a critical review of this area in
the hope of summarizing and integrating the current litera-
ture.
The purpose of this paper therefore is to present the `state-
of-the-art' regarding fear-avoidance in chronic musculoske-
letal pain, and its relevant consequences. We will review the
concept and theoretical underpinnings of the fear-avoidance
model and the existing evidence for the main predictions
that originate from this model. In addition, we shall criti-
cally appraise the currently available data relevant to assess-
ment methods and interventions based on the fear-
avoidance model. Finally we will provide some directions
for future research.
2. Early views on the role of fear on pain
The idea of a relationship between fear and pain is not
new. Historically, several authorities have expounded upon
the association between pain and fear. One of the ®rst philo-
sophers who linked pain with fear was Aristotle who wrote,
`Let fear, then, be a kind of pain or disturbance resulting
from the imagination of impending danger, either destruc-
tive or painful' (Eysenck, 1997). The major contribution of
Walter B. Cannon, who in 1915 wrote his in¯uential book
`Bodily changes in pain, hunger, fear and rage.', consisted
of upgrading the status of pain from a simple sensation to a
sensation accompanied by emotion. He was one of the ®rst
to demonstrate that pain is accompanied by increased adre-
nal secretions that were dependent on the sympathetic
nervous system, as is the case in fear and anxiety, but he
did not explicitly study the interrelation between pain and
fear. The phylogenetic origin of fear was thought to be
injury (Shepard, 1916), and later on, fear of injury or pain
was considered a salient and distinct kind of fear (Dixon et
al., 1957). In the 1960s, clinical researchers tried to gain
more insight into the association between pain and emotions
by examining the incidence of persistent pain in psychiatric
patients. Spear (1967), for example, found pain to be asso-
ciated relatively more often with anxiety disorders than with
other diagnoses. Sternbach (1974), describing the clinical
differences between acute and chronic pain, observed that
pain of recent onset was associated with a pattern of physio-
logical responses seen in anxiety attacks. In contrast,
chronic pain was characterized by an habituation of auto-
nomic responses and by a pattern of vegetative signs seen in
depressive disorders.
However, it was not until modern times that a model was
developed which relates fear and pain to behavior through
avoidance learning. Avoidance is a psychological term with
a relatively long history, but the term `fear-avoidance'
applied to the ®eld of pain ®rst appeared in an article by
Lethem et al. in 1983. These authors described a model
explaining how fear of pain and avoidance result in the
perpetuation of pain behaviors and experiences, even in
the absence of demonstrable organic pathology. Avoidance
behavior, presumably fueled by fear, has been intensively
studied since the 1960s (e.g. Rachlin, 1980). It refers to a
type of learned behavior, which postpones or averts the
presentation of an aversive event. Strictly taken, the term
`avoidance' is only used for behavior which postpones or
averts the aversive event. If the aversive event is terminated
by the behavior, the term `escape' is at stake. However, both
avoidance and escape are associated with negative reinfor-
cement (Kanfer and Phillips, 1970; Kazdin, 1980). Avoid-
ance learning occurs when the undesirable event has been
successfully avoided by the performance of a certain (avoid-
ance) behavior. Already in 1976, Fordyce devoted nearly
ten pages to avoidance learning to explain various pain
behaviors in chronic pain patients. Fordyce et al. (1982)
also described how individuals learn that the avoidance of
pain-provoking or pain-increasing situations reduces the
likelihood of new pain episodes. The authors also proposed
behavioral treatment approaches designed to modify these
learned behaviors. In synchrony with the so-called `cogni-
tive revolution' in behavioral science, Turk et al. (1983)
emphasized the role of attributions, ef®cacy expectations,
and personal control within a cognitive-behavioral perspec-
tive on chronic pain. The basic new assumption of this
approach is that individuals actively process information
regarding internal stimuli and external events. In this
context, Philips (1987) argued in favor of a cognitive
approach to avoidance behavior, rather than an instrumental
one. She took the view that avoidance is associated with the
expectancy that further exposure to certain stimuli will
promote pain and suffering.
Both the `instrumental' and the `cognitive' approach have
lead to in¯uential fear-avoidance models that purport to
explain how pain behaviors can be maintained in chronic
musculoskeletal pain. We describe these models in some
detail below since they are the basis for understanding the
fear-avoidance concept.
3. Model 1: the `activity' avoidance model
Fig. 1 shows the basic fear-avoidance conditioning model
speci®c for activities or movement and pain (Linton et al.,
1984). Generally, two components are distinguished: a clas-
sical and an operant one. The classical component refers to
the process in which a neutral stimulus receives a negative
meaning or valence. The person learns to predict events in
his/her environment. An injury elicits an automatic response
such as muscle tension and sympathetic activation including
fear and anxiety. An external stimulus may, through classi-
cal conditioning, elicit a similar response. Conditioning may
take place through direct experience, or by information
(vicarious learning) or even observation (modeling). For
example, a person involved in a traf®c accident may develop
a fear of driving as a result of the traumatic experience.
Likewise, a back pain patient may develop a fear of lifting
J.W.S. Vlaeyen, S.J. Linton / Pain 85 (2000) 317±332318
after experiencing pain while lifting or after receiving infor-
mation from a doctor that lifting can damage nerves in the
spinal cord. The same type of fear can also develop if a
person witnesses another person having an acute pain attack
as the result of lifting.
When the stimulus, which precedes the noxious or painful
experience, begins to predict the pain, avoidance learning
begins. The discriminative stimulus takes on negative
valence that activates muscle reactivity, fear, anxiety etc.
in itself. Avoiding the threatening situation, as illustrated in
Fig. 1, is reinforced by reductions, e.g. in pain, fear, tension
and anxiety. Once established, avoidance behavior is extre-
mely resistant to extinction (Rachlin, 1980). This is because
successful avoidance prevents the person from coming into
contact with the actual (non-harmful) consequences of the
threatening situation. Moreover, fear will return whenever
the avoidance behavior cannot be carried out.
4. Model 2: the `fear' avoidance model
A more cognitively oriented model of pain-related fear,
which builds upon the previous model, is presented in Fig. 2
(Vlaeyen et al., 1995a,b). This model serves as an heuristic
aid and ties several ®ndings in the more recent literature
together concerning the role of fear-avoidance in the devel-
opment of musculoskeletal pain problems. It postulates two
opposing behavioral responses: confrontation and avoid-
ance, and presents possible pathways by which injured
patients get caught in a downward spiral of increasing avoid-
ance, disability and pain. The model, which is based on the
work of Lethem et al. (1983); Philips (1987) and Waddell et
al. (1993), predicts that there are several ways by which pain-
related fear can lead to disability: (1) negative appraisals
about pain and its consequences, such as catastrophic think-
ing, is considered a potential precursor of pain-related fear.
(2) Fear is characterized by escape and avoidance behaviors,
of which the immediate consequences are that daily activities
(expected to produce pain) are not accomplished anymore.
Avoidance of daily activities results in functional disability.
(3) Because avoidance behaviors occur in anticipation of
pain rather than as a response to pain, these behaviors may
persist because there are fewer opportunities to correct the
(wrongful) expectancies and beliefs about pain as a signal of
threat of physical integrity. (4) Longstanding avoidance and
physical inactivity has a detrimental impact on the muscu-
loskeletal and cardiovascular systems, leading to the so-
called `disuse syndrome' (Bortz, 1984), which may further
worsen the pain problem. In addition, avoidance also means
the withdrawal from essential reinforcers increasing mood
disturbances such as irritability, frustration and depression.
Both depression and disuse are known to be associated with
decreased pain tolerance (Romano and Turner, 1985;
McQuade et al., 1988), and hence they might promote the
painful experience.
From a cognitive-behavioral perspective, there are a
number of additional predictions that can be derived from
this model: (5) just like other forms of fear and anxiety,
pain-related fear interferes with cognitive functioning. Fear-
ful patients will attend more to possible signals of threat
(hypervigilance) and will be less able to shift attention
away from pain-related information. This will be at the
expense of other tasks including actively coping with
problems of daily life. (6) Pain-related fear will be asso-
ciated with increased psychophysiological reactivity, when
the individual is confronted with situations that are
appraised as `dangerous'.
In the next section, we will review the existing evidence in
support of the above-mentioned predictions, point to lacunas
and discuss future directions.
J.W.S. Vlaeyen, S.J. Linton / Pain 85 (2000) 317±332 319
Fig. 1. The `activity' avoidance model, combining classical and operant conditioning paradigms. A threatening and pain producing situation (S
d
/CS) elicits a
conditioned response (CR) of sympathetic activation including fear, which in turn leads to avoidance of the situation (R). The avoidance behavior is reinforced
by a reduction of the unpleasant stimuli. CS refers to `conditioned stimulus' and CR to `conditioned response' in the classical paradigm. S
d
refers to
`discriminative stimulus', R to `response' and S
R2
to reinforcement consequences in the operant paradigm.
5. Negative appraisals as precursors of pain-related fear
`An ache beneath the sternum, in connoting the possibi-
lity of sudden death from heart failure, can be a wholly
unsettling experience, whereas the same intensity and dura-
tion of ache in a ®nger is a trivial annoyance easily disre-
garded'. With this statement, Henry Beecher (1959, p. 159)
emphasized the importance of cognitive processes in the
pain experience since pain lacks an external standard of
reference thus allowing considerable room for interpreta-
tion; more so than for example, normal vision or touch. A
recent cognitive-behavioral theory of anxiety, the so-called
`four-factor theory' assumes that the emotional experience
of anxiety is in¯uenced by four different sources of informa-
tion of which the cognitive appraisal of the situation is
considered the most important. The other three, which are
indirectly dependent on the ®rst, are the level of physiolo-
gical arousal, cognitions based on information stored in
long-term memory, and action tendencies and behavior
(Eysenck, 1997). In chronic pain, there is ample evidence
that certain pain-speci®c beliefs have an impact on chronic
pain adjustment. (For a review, see Jensen et al., 1991,
1994; Jensen and Karoly, 1992), but there are almost no
studies on the speci®c beliefs that in¯uence pain-related
fear. In fact, with the statement cited above, Beecher
gives an early example of what is now called a catastrophic
(mis)interpretation of a bodily sensation.
There is some evidence that catastrophizing thoughts
may be considered a precursor of pain-related fear. Pain
catastrophizing is considered an exaggerated negative
orientation toward noxious stimuli, and has been shown
to mediate distress reactions to painful stimulation (Sulli-
van et al., 1995). McCracken and Gross (1993) found a
signi®cant correlation between the catastrophizing scale
of the Coping Strategies Questionnaire (Rosenstiel and
Keefe, 1983) and the scores on the Pain Anxiety Symptoms
Scale (McCracken et al., 1992), a recently developed
measure of fear of pain. Vlaeyen et al. (1995a,b) found
that pain catastrophizing, measured with the Pain Cogni-
tion List (Vlaeyen et al., 1990) was superior in predicting
pain-related fear than biomedical status and pain severity.
In further support of this idea, Crombez et al. (1998a)
found that pain-free volunteers with a high frequency of
catastrophic thinking about pain became more fearful when
threatened with the possibility of intense pain than students
with a low frequency of catastrophic thinking.
A prospective study by Burton et al. (1995) concerning
predictors of back pain chronicity 1 year after the acute
onset is also worth mentioning in this context. These
researchers found that catastrophizing, as measured by
the Coping Strategies Questionnaire was the most power-
ful predictor: almost seven times more important than
the best of the clinical and historical variables for the
acute back pain patients. Additional evidence of the impor-
tance of catastrophizing is provided in a study comparing
chronic pain patients seeking help (consumers) with people
with chronic pain who were not having treatment, and
who were recruited via advertisements in local news-
papers (non-consumers). The results revealed that the
consumers reported much higher levels of pain catastrophiz-
ing than the non-consumers did (Reitsma and Meijler,
1997).
Constructs that appear to overlap considerably with cata-
strophizing, are negative affectivity and anxiety sensitivity.
Negative affectivity can be seen as a moderating variable
in the emergence of pain-related fear. According to Watson
and Pennebaker (1989), persons with high negative affec-
tivity are hypervigilant for all forms of (external and inter-
nal) threat, and therefore are considered more vulnerable to
develop speci®c fears (Eysenck, 1992). For individuals
with high negative affectivity who also experience pain,
pain may be the most salient threat, and as a consequence,
pain-related fear may emerge. Reiss and McNally (1985)
introduced a fear-expectancy model of avoidance behavior
that is based on the idea that anxiety disorders occur more
frequently in patients with a speci®c personality character-
istic which they called `anxiety sensitivity'. This should be
seen as a speci®c tendency to react anxiously to one's own
anxiety and anxiety-related sensations (fear of fear).
Asmundson and Norton (1995) found that chronic back
pain patients with high anxiety sensitivity reported more
fear of pain and tended to have greater avoidance of activ-
ities than those with lower anxiety sensitivity, despite equal
levels of pain. In a subsequent study using structural equa-
tion modeling, Asmundson and Taylor (1996) corroborated
the ®nding that anxiety sensitivity directly exacerbates fear
of pain, even after controlling for the effects of pain sever-
ity on fear of pain. However, anxiety sensitivity affected
escape and avoidance behaviors indirectly, via fear of pain.
These ®ndings would support Reiss's (1991) view that
more basic fears (such as fear of somatic sensations, fear
of cognitive dyscontrol, or fear of being outwardly
anxious) underlie many speci®c fears, and that these should
be considered a more general vulnerability factor for the
development of these speci®c fears (see Asmundson et al.,
1999).
Fears can also originate from traumatic experience.
Within 1±4 months after a motor vehicle accident, 39%
of the victims develop a post-traumatic stress disorder
(Blanchard et al., 1996). Turk and Holzman (1986)
suggested that fear-avoidance beliefs in chronic pain
patients may be especially salient when the original acute
pain problem resulted from sudden traumatic injury.
Further evidence for this assumption was found by Vlaeyen
et al. (1995b) and Crombez et al. (1999). Chronic low back
pain patients who retrospectively reported a sudden trau-
matic pain onset, scored higher on the Tampa Scale for
Kinesiophobia than patients who reported that the pain
complaints started gradually. Additionally, there is
evidence that a large percentage of people with chronic
musculoskeletal pain meet DSM-IV criteria for post-trau-
matic stress disorder (Asmundson et al., 1998).
J.W.S. Vlaeyen, S.J. Linton / Pain 85 (2000) 317±332320
6. Pain-related fear and the overprediction of pain
Almost half a century ago, Hill et al. (1952) observed in
their study on the effects of anxiety and morphine on discri-
mination of intensities of painful stimuli that under condi-
tions promoting anxiety or fear of pain, subjects tended to
overestimate the intensities of painful stimuli. More
recently, in a series of studies with laboratory-induced
pain, Arntz et al. (1990) concluded that anxious subjects
produced more overpredictions of pain and that these over-
predictions were less easily discon®rmed than those of the
non-anxious subjects were. In a clinical setting, McCracken
et al. (1993) investigated associations among predictions
about pain, pain-related fear using the pain anxiety symp-
toms scale and range of motion in 43 chronic back pain
patients who were exposed to pain during a physical exam-
ination. During the examination, patients were requested to
repeatedly raise the extended leg to the point of pain toler-
ance. They found that anxious patients showed a tendency to
overpredict pain early in the sequence of pain, while the low
anxious patients underpredicted pain. Moreover, a signi®-
cant relation between prediction of pain and range of motion
during the straight leg raise was found, suggesting that those
who expect more pain avoid pain increase by terminating
the leg raise earlier. Of interest, however, is that patients
tend to correct their pain expectancies when they are given
the opportunity to repeat the same pain-eliciting activity.
When chronic back pain patients were requested to perform
four exercise trials consisting of ¯exing and extending the
knee three times at maximal force (with a Cybex 350
system), Crombez et al. (1996) found that after overpredict-
ing the pain experienced during the ®rst exercise bout, the
reported pain expectancy was corrected during the next
exercise bout. In other words, after some exposures, over-
predictions of pain intensity tended to match actual experi-
ence. The important clinical implication is that fearful
patients may bene®t from graded exposure to movements
and activities that they previously avoided.
7. Pain-related fear and physical performance
Does pain-related fear also affect physical performance?
One of the main features of fear and anxiety is the tendency
to escape from and avoid the perceived threat. Although
chronic pain in itself cannot always be avoided, the activ-
ities assumed to increase pain or (re)injury may be. One of
the consequences, however, is that daily activity levels
decrease, possibly resulting in functional incapacity. A
number of studies have investigated the association between
pain-related fear and physical performance, which are
summarized in Table 1. In the above-mentioned study by
McCracken et al. (1992), a signi®cant correlation was found
between pain-related fear and range of motion as measured
with a ¯exometer. Vlaeyen et al. (1995a) used a simple
lifting task during which patients were asked to lift a 5.5
kg weight with the dominant arm and hold it until pain or
physical discomfort made it impossible for the patient to
continue. A signi®cant correlation was found between lift-
ing time and the Tampa Scale for Kinesiophobia (TSK). In
J.W.S. Vlaeyen, S.J. Linton / Pain 85 (2000) 317±332 321
Table 1
Correlations of pain-related fear and behavioral performance measures
Authors N Behavioral
performance measure
Pain±related fear Correlation P
McCracken et al. 1992
a
43 Straight leg raising test PASS 20.36 ,0.05
Vlaeyen et al. 1995a 33 Lifting a 5.5 kg weight TSK 20.44 ,0.01
Crombez et al. 1998 49 Knee-extension-¯exion
Unit of the Cybex 350
System
LBPQ
Peak torque Fear of pain 20.16 NS
Performance variability 0.31 ,0.025
Work ratio 0.38 ,0.005
Peak torque Fear of (re)injury 20.27 ,0.05
Performance variability 0.33 ,0.025
Work ratio 0.39 ,0.005
Crombez et al. 1999 38 Trunk-extention-¯exion
unit of the Cybex 350
system
Peak torque TSK 20.40 ,0.01
FABQ±physical 20.45 ,0.01
FABQ±work 20.10 NS
Lifting a 5.5 kg weight
TSK 20.49 ,0.01
PASS 20.33 ,0.01
a
Findings are based on a re-analysis of the data (McCracken, pers. commun.). PASS, Pain Anxiety Symptoms Scale (McCracken et al., 1992); TSK, Tampa
Scale for Kinesiophobia (Kori et al., 1990); LBPQ, Leuven Back Pain Questionnaire (Crombez et al., 1998); FABQ, Fear Avoidance Beliefs Questionnaire
(Waddell et al., 1993).
