| Abstract |
Background Musculoskeletal problems in working populations constitute an
important cause of lost workdays, reduced productivity and increased use of health
services and residual disability affecting the active population of a country. The majority
of relevant studies conclude that physical, organizational and psychosocial factors at
work are risk factors for musculoskeletal pain. Pathophysiological theories behind these
factors reflect local physical stressors generating local complaints. On the other hand,
multisite pain has rarely been studied. It usually is treated as a confounding or
prognostic factor and rarely as a primary outcome.
Scope: The scope of the present study was to investigate the role of psychosocial,
occupational and individual factors that associate with multisite pain in working
populations. The specific objectives were:
a. to implement the Greek branch of the international CUPID study about Cultural and
Psychosocial Influences on Disability.
b. to estimate the prevalence of localized and multisite pain in three occupational groups
c. to identify possible risk factors that associate with the number of body sites in pain
d. to estimate the relative importance of these determinants, and
e. to study multisite pain overtime for a 12 months period of time and identify factors
relating to new onset and/or persistent multisite pain.
Material-Methods The study population consisted of three groups of professionals
from Crete: postal clerks sorting mail by hand, nurses and office workers. We finally
recruited 518 participants. We contacted them in two time points. At baseline, during a
structured personal interview, we collected demographic information and details about
psychosocial and physical factors at work, low mood, somatizing tendency, alexithymia
(difficulty identifying and expressing one’s own feelings and the feelings of others),
depression, perceptions about pain causation and fear avoidance beliefs, and
information about musculoskeletal pain that may have had occurred during the
preceding 12 months lasting for at least one day in the low back, neck, shoulder, elbow,
wrist/hand and knee. At follow up, one year later, we collected information about
musculoskeletal pain in the past month for the same body sites,
Statistical analysis: We used poisson regression to investigate the association of
demographic, occupational and psychosocial factors to a. The number of body sites that
were in pain, b. the number of body sites that were in frequent pain, and c. the number
of body sites that were in disabling pain. We evaluated the relative importance of each
one of those factors using the CART analysis (Classification and Regression Tree
Analysis). We used logistic regression to investigate potential risk factors for persistent
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and new onset multisite pain and linear regression to investigate for associations with
global low back pain and low back pain disability scores.
Results From a total of 596 eligible subjects, 564 participated at baseline and 518 of the
also participated at follow up. Overall response rate 87%.
The 12 month prevalence of low back pain and neck pain was particularly high, 63% and
48% respectively, and were followed by wrist/hand pain (38%), shoulder pain (37%),
knee pain (26%) and elbow pain (20%). Two thirds of the study participants had pain in
more than two body sites and 23% of participants had pain in more than three sites.
Multisite pain with additional characteristics such as high frequency (more than 30 days
in total in the past 12 months) and/or resultant disability (difficulty in performing two
or more everyday chores) was less frequent and was reported by 4-5% of the study
sample. Sixty-two per cent of participants with multisite pain at baseline also reported
multisite pain at follow up 12 months later, whereas the incidence of new onset multisite
pain was 16% for the 12 before follow up.
Somatizing tendency and physical load at work, as well as perceptions that
musculoskeletal pain might be caused by work were positively associated with the
number of painful body sites. Job satisfaction and support from colleagues and/or
supervisor were negatively associated with the number of painful body sites. Being in
the grey zone for alexithymia was inversely associated with the number of painful body
sites, thus implying a dose- response relationship which would best be described with a
U-shaped curve. CART analysis indicated somatizing tendency as the leading
determinant of the number of body sites that were in pain.
Somatizing tendency appeared to be a confounder in the relation between a. physical
load and b.psychosocial factors at work with global low back pain score and low back
pain disability score.
Forty or more hours per week at work seemed to be associated with new onset multiple
pain (OR: 5.0, 95%CI:1.1-24.0), whereas high physical load at work (OR:5.1, 95%CI:2.1-
12.2), high somatizing tendency (OR: 3.3, 95% CI: 1.9-5.5) , low mood (OR: 1.8, 95% CI:
1.0-3.2), neuroticism score (Coeff: 1.05, p-value: 0.05) and work causation beliefs (ΟR:
2.2, 95% CI: 1.3-3.8), presented as risk factors for the development of persistent multisite
musculoskeletal pain one year later.
Conclusion Localized musculoskeletal pain was frequent in our study sample, and
multisite pain was a little bit more frequent. The results from our analyses are in favor of
the hypothesis that occupational as well as psychosocial factors associate with persistent
multisite pain. Somatizing tendency presented to have a particularly important role.
More research is needed in order to clarify whether multisite pain is associated with a
different set of determinants as compared to localized pain; moreover if a different set of
determinants is related to the development of a first episode of multisite pain as
compared to its transition to chronicity.
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Psychosocial factors at work .Their association to musculoskeletal symptoms and disability
