The level of physical activity and participation in society of adolescents with chronic musculoskeletal pain.

Previous research has demonstrated that children and adolescents frequently
experience and report chronic pain. Among school children up to 25% is
suffering of chronic or recurrent pain of three months or longer. In a
substantial part of these cases no specific cause can be identified for the
pain condition. Common complaints encountered in non-specific pain are
headache, musculoskeletal pain, abdominal pain and back pain. Girls more often
report pain than boys and the incidence peaks during adolescence.
Until recent years, evidence based knowledge on chronic pain in childhood and
adolescence was scarce, especially in comparison with evidence on chronic pain
in adulthood. However, as a result of increasing consideration on the fact that
many children and adolescents with chronic pain will grow into adults disabled
by chronic pain involving high societal costs, more research has been
undertaken on this subject over the past few years.
Nevertheless, a few subject areas remain underexposed. Firstly, only a minority
of the published studies on this subject concern musculoskeletal pain in
specific. In previous research, children and adolescents presenting with
headache or abdominal pain accounted for the majority of the study population.
Although these are the most common pain localisations among children and
adolescents in general, most referrals to rehabilitation medicine are children
and adolescents presenting with musculoskeletal pain. Therefore, for
rehabilitation medicine it would be relevant to focus on this non-specific pain
condition and to increase knowledge of this group of patients.

Secondly, the effect of chronic pain on the functioning of children and
adolescents suffering from it has not been studied properly. Most studies
published on this area focused predominantly on the negative consequences of
chronic pain as a study outcome, such as impairments and disability. However,
according to the the International Classification of Functioning, Disability
and Health (ICF, WHO 2001), a framework developed by the WHO to describe
functioning and disability at both individual and population level, functioning
is seen in a more holistic view and is described in positive instead of
negative terms. Based on this model, functioning is seen in relation to health
conditions, personal and environmental factors, and has two components: *body
functions and structures* and *activities and participation*. Activities refers
to executing daily life tasks and activities, whereas participation refers to
the actual involvement in specific life situations, ie social engagement.
Evidence based knowledge on the functioning of children and adolescents with
chronic pain in positive terms such as *activities and participation* is scarce
in comparison with knowledge on negative outcomes such as disability, defined
as problems in executing daily life tasks and activities. Therefore, it would
be interesting to chart the level of activities and participation of children
and adolescents with chronic pain, such as mobility, self-care, carrying out
domestic and everyday actions and tasks and carrying out actions required to
engage in education.

Finally, our knowledge about factors influencing the functioning of children
and adolescents with chronic pain in general and more specific, factors
influencing their level of activities and participation in society is still
underdeveloped. Although many children and adolescents experience acute pain,
only a minority of these develop chronic pain and become disabled by it, i.e.
experiencing problems in executing daily tasks and activities. Previous studies
have tried to identify factors related to the development and maintenance of
chronic pain and pain related disability in adolescence, such as low pain
thresholds, previous pain experience and maladaptive coping strategies. In
order to better understand why only a minority develop a chronic pain problem
and to identify factors of influence it is necessary to hypothesize a model of
pain and interacting factors. A traditional biomedical approach is insufficient
to explain chronic pain and its associated disability. Numerous studies among
adults with chronic pain suggest that behavioral and biopsychosocial factors
contribute to the development and maintenance of chronic pain. The
fear-avoidance model explains how and why adults with acute musculoskeletal
pain develop a chronic pain syndrome. Although this model has not been used to
explain the development of chronic pain in children and adolescents until now,
it seems reasonable that this model is also applicable to this group.
Therefore, in the present study we chose this model in order to better
understand the chronic pain problem in children and adolescents.
According to the fear-avoidance model, pain is interpreted as either
non-threatening or threatening, leading to two different pathways. In the first
situation rapid confrontation with daily activities is likely to occur,
promoting functional and fast recovery. In contrast, when pain is
catastrophically (mis)interpreted as threatening, a vicious circle may be
initiated. These dysfunctional interpretations of pain give rise to
pain-related fear and associated behaviors in order to reduce fear and anxiety
in the short term, such as avoidance behavior and hypervigilance. In other
words, when patients experiencing acute pain interpret their pain as
threatening, fear of movement and injury occurs. The expectation of negative
consequences of increasing their physical activity may be the reason to avoid
physical activities, on long term leading to disability, i.e. problems in
executing daily tasks and activities, and disuse, defined as performing at
reduced level of physical activity in daily life. In addition to the
development of disability and disuse, avoidance of daily physical activities
may also result in depressive symptoms according to the fear-avoidance model.
It is imaginable that disability, disuse and depressive symptoms will lead to a
lower level of participation in society.

Until recently, it was assumed that pain intensity did not play an important
role in the fear-avoidance model. However, more recent literature on the
fear-avoidance model shows that this assumption is not true for adults with
acute low back pain and that pain intensity in itself has a considerable
contribution in explaining disability.

In view of the above mentioned, it is imaginable that the components or factors
of the fear-avoidance model, such as pain-related fear, pain catastrophizing,
avoidance behavior, depressive symptoms and pain intensity, have a negative
influence on the level of activities and participation in society of children
and adolescents with chronic pain. Although this seems presumable, there is no
evidence based knowledge on this area among children and adolescents with
chronic pain. Because of the feasible implications regarding understandig of
pediatric chronic pain and its management it is considered relevant to evaluate
this. One possible way to analyze this is to investigate the influence of
pain-related fear, pain catastrophizing, avoidance behavior, depressive
symptoms and pain intensity on the level of activities and participation.

Therefore, the present study aims to determine the level of activities and
participation among children and adolescents with chronic musculoskeletal pain
in comparison with children and adolescents not suffering from chronic pain.
Further, the second objective of this study is to assess factors influencing
the level of activities and participation of children and adolescents suffering
from chronic musculoskeletal pain. We chose to analyze the impact of three
factors or components from the fear-avoidance model, ie pain catastrophizing,
pain intensity and depressive symptoms.

Hypotheses:
1. Adolescents with chronic pain have lower level of activities in daily life
and a lower level of participation in society as compared to healthy peers.
2. A higher level of catastrophizing, pain intensity and a depressive symptoms
will result in a lower level of activities in adolescents with chronic pain.
3. A higher level of catastrophizing, pain intensity and depressive symptoms
will result in a lower level of participation in society in adolescents with
chronic pain.

1. Is there a difference between the level of activities and participation
among adolescents with chronic musculoskeletal pain as compared with the
activity and participation level of adolescents not suffering from chronic pain?
2. What is the impact of pain catastrophizing, pain intensity and depressive
symptoms on the level of activities in daily life of adolescents suffering from
chronic musculoskeletal pain?
3. What is the impact of pain catastrophizing, pain intensity and depressive
symptoms on the level of participation in society of adolescents suffering from
chronic musculoskeletal pain?

Patient control study in a cross sectional design.

The burden for the adolescents will be restricted to the one-only filling-in of
a questionnaire. This takes about 90 minutes. The questionnaire consists of the
following measurement instruments:

- Demographic and medical variables: age, gender, duration of pain, education,
absence from school, hobbies, family type, presence of family members with
chronic pain and comorbidity will be recorded.
- Pain Catastrophizing Scale for Children (PCS-C): catastrophic thinking about
pain will be assessed with the Dutch version of the Pain Catastrophizing Scale
for Children (PCS-C) (Crombez et al., 2003). This instrument consists of 13
items describing different thoughts and feelings that children may experience
when they are in pain. Children rate how applicable each of the described
thoughts and feelings are when they are in pain using a 5-point scale (0-4).
Total scores are obtained by summing the ratings for each item. The PCS-C has
shown to be a reliable and valid instrument for children aged 9 to 15 (Crombez
et al., 2003).
- Visual analogue scale (VAS): the intensity of current pain will be assessed
with a 10 cm visual analogue scale (VAS) with the endpoints *no pain* and *a
lot of pain*. The pain severity VAS has a good reliability and validity in
children 9-15 years old (McGrath, 1987).
- Children*s Depression Inventory (CDI): depressive symptoms will be measured
by the Dutch version of the Children*s Depression Inventory (CDI) (Kovacs,
1981). The CDI is a self-report inventory that assesses symptoms of depression
in children and adolescents. It is suitable for youths aged 7 to 17. It
contains 27 self-report items on five subscales (negative mood, interpersonal
problems, ineffectiveness, anhedonia, negative self-esteem), representing
depressive symptoms. Each item is rated on a 3-point scale and summed to obtain
a total score. Higher scores indicates higher levels of depressive symptoms.
The CDI has been found to have acceptable reliability and good validity
(Smucker et al., 1986) (Claar & Walker, 2006) (Eccleston et al., 2006).
- Functional Disability Inventory (FDI): pain-related disability will be
assessed with the Dutch version of the Functional Disability Inventory (FDI)
(Walker and Greene, 1991) (Dutch version: Crombez et al., 2003). The FDI is a
self-report inventory for children that measures perceived difficulty in
performing a number of activities in the domains of school, home, recreation
and social interactions. It is designed to be applicable to a broad range of
illnesses and varying levels of severity. The instrument consists of 15 items
concerning perceptions of activity limitations during the past two weeks. The
items are rated on a 5-point scale (0-4). Total scores are obtained by summing
the ratings for each item. Higher total scores indicate greater disability. The
reliability and validity has been demonstrated in research (Walker & Greene,
1989) (Claar & Walker, 2006) (Eccleston et al., 2006).
- Short Questionnaire to Assess Health-enhancing physical activity (SQUASH)
(Wendel-Vos et al., 2003): the SQUASH is a reliable and valid questionnaire
developed by the Dutch National Institute of Public Health and the Environment
to assess habitual physical activity in an adult population. It consists of
questions concerning the frequency and duration of habitual physical activity
in 4 domains, i.e. commuting activities, leisure time activities, household
activities and activity at work and school. The SQUASH is designed for persons
16 years and above. There is also a modified version of the SQUASH especially
designed for adolescents: the Activity Questionnaire for Adults and Adolescents
(AQuAA). The Dutch translation of this questionnaire is in validation and the
publication will be expected in short term. In the current study we will use
the modified version of the SQUASH to measure the physical activity.
-General Questionnaire Children*s Rehabilitation Pain and Fatigue (Westendorp,
2007): this Dutch instrument measures the level of physical activity of
adolescents. It is designed especially for children suffering from chronic pain
and contains a section titled *Sports/ hobby*s* measuring the level of
activities in this group. Unfortunately, it has not been validated until now.
- Children*s Assessment of Participation and Enjoyment (CAPE) and the
Preferences for Activities of Children (PAC) (King et al., 2007): for
measuring the level of participation in society the Dutch translation of these
2 complementary questionnaires will be used. Both self-report inventories
consist of 55 items and are appropriate to measure participation in recreation
and leisure activities outside of school for children and adolescents aged 6 to
21. They provide information about 5 types of activities: recreational, active
physical, social, skill-based and self-improvement activities. The CAPE
provides information about 5 dimensions of these 5 types of participation, i.e.
diversity, intensity, where, with whom and enjoyment. The PAC is a additional
measure for a sixth dimension, i.e. preference for activities. The English
version of the CAPE and PAC have been found to have good validity (King et al.,
2007). The Dutch translation of these questionnaires are in validation and the
publication of the validation study will be expected in short term.

In addition, the healthy peers will be asked to fill in a questionnaire
including the demographic variables, the SQUASH, the additional measure for
level of activities and the CAPE and PAC. The pain related measures will no be
included in this questionnaire. Therefore, it will take less time to fill in
the questionnaire (70 minutes).