Risk factors which influence the
evolution of acute pain into
chronic pain
Systematic Review
Class 6
Faculty of Medicine – University of Porto
Department of Biostatistics and
Medical Informatics
Introduction
Pain
• Unpleasant sensory and emotional experience
associated with actual or potential tissue damage [1].
Acute Pain & Chronic Pain
• Chronic pain is a pain without apparent biological value
that has persisted beyond the normal tissue healing time
(taken to be three months), whereas acute pain tends to
have shorter duration, as well as it is connected with
tissue lesions [2].

It is estimated that between 10 and 15 % of the
population suffers from chronic pain [2].
[1] Iasp-pain.org [Homepage on the internet]. IASP – International Association for the Study of Pain; [updated 2005 Oct 10; cited 2005 Dec
13]. Available from: http://www.iasp-pain.org/
[2] Smith BH, Hopton JL, Chambers WA. Chronic pain in primary care. Family Practice. 1999; 16: 475-482 .
Objective
• To review systematically the literature
regarding risk factors which influence the
evolution of acute pain into chronic pain
Methods
Inclusion criteria:
 Cohort studies that refer to the factors which influence
the evolution of acute pain into chronic pain.
Exclusion criteria:
 Language restriction: only studies in English or
Portuguese would be included.
 Studies that are not connected with the context of our
review.
 Studies that are not cohort studies.
 Studies that do not refer the evolution of acute pain into
chronic.
Methods
Query:
• “Chronicity AND Pain”
Electronic databases used:
• Medline [16] (Nov 2005)
• Scopus [17] (Apr 2006)
Articles obtained in the research:
• Medline – 376 articles
• Scopus – 505 articles (361 are included in Medline’s
research)
[16] Medline [database on the Internet]. National Library of Medicine (US); 2002 – [cited 2005 Nov]. Available from:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed
[17] Scopus [database on the Internet]. New Jersey Institute of Technology (USA); [cited 2006 Mar]. Available from:
http://www.scopus.com/scopus/home.url
Assessment Protocol (Medline)
Organization of reviewer groups:
4 Reviewer Groups: three groups of 2 elements and one
group of 3 elements
Revision by abstract:
All groups reviewed a sample of 6 articles
Two groups with 93 articles and two groups with 92 articles
Revision by full text:
Three groups with 17 articles and one group with 18
articles
Assessment Protocol (Scopus)
Organization of reviewer groups:
4 Reviewer Groups: three groups of 2 elements and one
group of 3 elements
Revision by abstract:
Each reviewer group with 36 articles
Revision by full text:
Each reviewer group with 2 articles
Start
Bibliografic Research
Definition of Query
Fluxogram
Medline: 376
Articles
Scopus: 505
Articles
Selected Articles 520
(361 in comum; 15 only in Medline;
144 only in Scopus)
Articles Revision by
Title and/or Abstract
Included or Excluded
(by applying exclusion criteria)?
Excluded Articles
443
Excluded
Included
Remaining Articles
Revision by Full
Text
Included or Excluded
(by applying exclusion criteria)?
Excluded Articles
72
Excluded
Included
Articles Included in the
Sistematic Review
5
End
Selected Articles
n=520
(361 in comum; 15 only in Medline;
144 only in Scopus)
Articles Revision by
Title and/or Abstract
n=520
Articles
Selection
Excluded Articles
n=443
Reason for exclusion:
Articles nor in English nor in Portuguese n=75
Articles not related with the context of the review n=245
Not a cohort study n=54
Article that do not refer the evolution of acute pain into
chronic n=69
Remaining Articles
Revision by Full Text
n=77
Excluded Articles
n=72
Articles Included in the
Sistematic Review
n=5
Reason for exclusion:
Articles not found in full text n=39
Articles not related with the context of the review n=9
Not a cohort study n=13
Article that do not refer the evolution of acute pain into
chronic n=11
Results
Table 1 - Main features of the studies used in the review
Country
Sample
Size
Follow up
Period
(months)
Follow up
losses
Kind of
pain
Reference
Publication
Publication
year
Francen, M. et al.
Spine
2002
Australia
854
20
586
Low back
pain
Williams, R. et al.
Archives
of PMR
1998
USA
117
6
6
Low back
pain
Andersson, H.
European
JournalPain
2003
Sweden
214
144
73
Neckshoulder
pain
Gatchel, R. J.
Health
Psychology
1995
USA
324
6
14
Low back
pain
Spine
1987
UK
11
12
-----
Low back
pain
Klimiuk, P.S. et al
Results
Table 2 - Inclusion and exclusion criteria of the sample’s subjects
Reference
Inclusion Criteria
Fransen, M. et
al [8]
•Nurses
•Nurses' aids
•Heavy manual workers
•Drivers
Exclusion Criteria
Williams, R. et
al [10]
•Age between 15 and 18 years
•Back pain (T6 or below) that had been present "on a
daily bases" from the previous 8 weeks as the only
pain problem
Andersson, H.
[11]
•Neck/shoulder pain with or without reflexion in arms
•Pain in at least 3 regions of arms/legs
Gatchel, R. J. et
al [12]
•Lumbar pain with duration inferior to 6 weeks
•Unemployed people
•Presence of a first episode of acute low back pain
and sciatica
•Patients had no other active disease, with no
evidence of ankylosing spondylitis as demonstrated
by normal sacroiliac joints on radiography and the
absence of tissue type HLA B27
•In all subjects the ESR blood count, serum calcium,
phosphate, and alkaline phosphatase levels are
normal
•No patients had been exposed to any
invasive
procedure
other
than
venepuncture within the previous 3 months
Klimiuk, P.S. et
al [13]
•Taking medications known to affect mood
•Prior back surgery
•Pain secondary to neoplastic disease
osteomyelitis, or fracture since the clinical
course of these conditions differs from the
"usual" back disorder
Results
Table 3 – Individual characteristics of subjects that influence the evolution into chronic pain
Reference
Studied factors
Increasing age (>46)
1.61 (1.05-2.47)*
Severe radiating pain in legs
2.3 (1.44-3.76)*
Normal body mass index
Fransen et
al [8]
Andersson,
H [11]
Gatchel, R.
et al [12]
OR (95%CI)
Higher than normal body mass index
Oswestry Disability score indicating minimal disability
1.0*
1.85 (1.17-2.90)*
1.0*
Oswestry disability score indicating moderate disability
3.48 (1.65-7.35)*
Oswestry disability score indicating severe disability
5.89 (2.84-12.20)*
Oswestry disability score indicating extreme disability
5.69 (2.73-11.89)*
Chilliness
1.73 (0.44-6.83)**
Stiffness
1.09 (0.35-3.40)**
Number of painful areas 1-3
3.34 (1.43-7.79)**
Number of painful areas >3
15.8 (4.53-55.3)**
Race
0.207-1.152
Age
0.925-1.818
Pain and disability analogue
1.307-2.007
*Odds ratios (age- and gender-adjusted) for chronicity
** Adjusted odds ratio (no data on adjusting factors
Table 4 – Psychosocial characteristics of subjects that
influence the evolution into chronic pain
Reference
Studied factors
OR (95% CI)
Somatic symptoms
1.31 (0.95-1.81)*
Anxiety/insomnia
2.08 (1.50-2.89)*
Social dysfunction
2.79 (1.98-3.93)*
Severe depression
2.47 (1.66-3.67)*
Job insatisfaction
1.14 (0.80-1.64)*
New family member gained
0.60 (0.39-0.91)*
Andersson, H [11]
Having a close friend outside the family
0.44 (0.21-0.92)**
Gatchel, R. et al [12]
Axis II personality disorder
Fransen et al [8]
*Odds ratios (age- and gender-adjusted) for chronicity
** Adjusted odds ratio (no data on adjusting factors)
0.874-4.415
Table 5 –Workplace factors that influence the evolution into
chronic pain
Reference
Fransen et al [8]
Andersson, H [11]
Studied factors
OR (95% CI)
Need to manoeuvre "extremely heavy" items
regularly
1.48 (1.08-2.04)*
Need to spend, at least, 3/4 of the working day
driving
1.82 (1.03-3.22)*
Unavailability of light duties on return to work
1.99 (1.39-2.86)*
Lifting time for about half a day
1.52 (1.01-2.24)*
Lifting time for about three fourths or more a day
2.04 (1.41-2.96)*
Work in a bent position
5.31 (1.19-23.6)**
*Odds ratios (age- and gender-adjusted) for chronicity
** Adjusted odds ratio (no data on adjusting factors)
Discussion
• Relevant Results
• Physical, Psychological and Workplace factors
influence the evolution of acute pain into chronic
pain
• Physical factors play the greatest influence
• Number of painful areas >3 (OR 15.8)
• Oswestry disability score indicating severe disability (OR 5.9)
• Oswestry disability score indicating extreme disability (OR 5.7)
Discussion
• Relevant Results
• Aggressive modifications on daily routine that
draw patients attention from pain reduce the risk
of chronicity
•
•
New family member gained (OR 0.6)
Beginning of a different job (OR 0.7)
• Work conditions when returning to duties
influence chronicity
• Unavailability of light duties on return to work (OR 1.9)
• Special tasks and psychological support for people recovering from acute pain
might reduce company’s expenses with monetary compensation during
inability and increase job satisfaction
Discussion
• Connection with existent literature

The results presented agree with previous literature,
supporting the evidence found for the influence of
certain psychological factors in the progression to
chronicity in Low Back Pain [15]
[15] Pincus T, Burton AK, Vogel S, Field AP. A Systematic Review of Psychological Factors as Predictors of Chronicity/Disability
in Prospective Cohorts of Low Back Pain. Spine. 2002. Volume 27, number 5, pp E109-E120.
Discussion
• Methodological and Data limitations
• Query Definition
• Cohort Studies
• Longitudinal prospective studies give reliable data, as they follow the
•

participants while the causes play their role
However they lose a significant percentage of the initial sample,
reducing the statistical significance of conclusions
Heterogeneity

The heterogeneity verified among the studies reduced the possibility
of aggregating the results
Discussion
• Methodological and Data limitations

Articles

There are several studies concerning chronic pain and how it
should be handled, but few about factors that promote
chronicity

When factors are studied, they are usually acessed whithin
chronicity

Further studies should be carried out, as this is an important
issue with psychological, social and economic implications
Discussion
• Conclusions
• Physical, Psychological and Workplace factors
influence the evolution of acute pain into chronic pain
• Physical factors play the greatest influence
• Further studies should be carried out
References
[1] Iasp-pain.org [Homepage on the internet]. IASP – International Association for the Study of Pain; [updated 2005 Oct 10; cited 2005 Dec 13]. Available
from: http://www.iasp-pain.org/
[2] Smith BH, Hopton JL, Chambers WA. Chronic pain in primary care. Family Practice. 1999; 16: 475-482 .
[3] Purves AM, Penny K, Munro C. Defining chronic pain for epidemiological research – acessing a subjective definition. The Pain Clinic. 1998; 10: 139147.
[4] IASP – Pain Clinical Updates; volume XI, No. 2; June 2003
[5] Von Korff M, Dworkin SF, Le Resche L. Graded chronic pain status: an epidemiologic evaluation. Pain. 1990; 40: 279-291.
[6] Bowsher D, Rigge M, Sopp L. Prevalence of chronic pain in the British population: a telephone survey of 1037 households. The Pain Clinic. 1991; 4:
223-230.
[7] Brattberg G, Thorslund M, Wilkman A. The prevalence of pain in the general population. The results of a postal survey in a county in Sweden. Pain.
1989; 37: 215-222.
[8] Fransen M, Woodward M, Norton R, Coggan C, Dawe M, Sheridan N. Risk Factors Associated with the Transition From Acute to Chronic Occupational
Back Pain. Spine. 2002; 27(1): 92-98.
[9] Pai M, McCulloch M, Gorman JD, Pai N, Enanoria W, Kennedy G et al. Systematic reviews and meta-analyses: An illustrated, step-by-step guide. The
National Medical Journal of India. 2004; 17(2): 86-95.
[10] Williams RA, Pruitt SD, Doctor JN, Epping-Jordan JE, Wahlgren DR, Grant I, et al. The contribution of job satisfaction to the transition from acute to
chronic low back pain. Archives of physical medicine and rehabilitation. 1998 April; 79: 366-374.
[11] Andersson H. The course of a non-malignant chronic pain: a 12-year follow-up of a cohort from the general population. European Journal of Pain. 2004;
8: 47-53.
[12] Gatchel RJ, Polatin PB, Kinney RK. Predicting outcome of chronic back pain using clinical predictors of psychopathology: a prospective analysis.
Health Psychol. 1995 Sep; 14(5): 415-20.
[13] Klimiuk PS, Pountain GD, Keegan AL, Jayson MI. Serial measurements of fibrinolytic activity in acute low back pain and sciatica. Spine. 1987
Nov;12(9): 925-8.
[14] Fairbanks JC, Coouper J, Davies JB, et al. The Oswetry Low Back Pain Disability Questionnaire. Physioteherapy 1980; 66:271-3
[15] Pincus T, Burton AK, Vogel S, Field AP. A Systematic Review of Psychological Factors as Predictors of Chronicity/Disability in Prospective Cohorts
of Low Back Pain. Spine. 2002; Volume 27, number 5, pp E109-E120.
[16] Medline [database on the Internet]. National Library of Medicine (US); 2002 –
[cited 2005 Nov]. Available from:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed
[17] Scopus [database on the Internet]. New Jersey Institute of Technology (USA); [cited 2006 Mar]. Available from:
http://www.scopus.com/scopus/home.url