Dieppe, Paul

Learmonth, Ian D

Palmer, Shea

Wylde, Vikki

English

PubMed

Vikki Wylde

Shea Palmer

Ian D Learmonth

Paul Dieppe

Springer - Publisher Connector

POSTER PRESENTATION Open Access
Pain assessment: the relationship between pain
thresholds and pain severity in osteoarthritis
Vikki Wylde1*, Shea Palmer2, Ian D Learmonth1, Paul Dieppe3
From Clinical Trials Methodology Conference 2011
Bristol, UK. 4-5 October 2011
Objectives
When pain is assessed in research, it is most commonly
assessed using patient-reported outcome measures
(PROMS). These measures can provide information
about pain severity, distress and qualities, but they are
unable to provide information about the underlying
mechanisms contributing to pain perception. Quantita-
tive Sensory Testing (QST) comprises non-invasive tests
which can identify abnormalities in pain processing on a
localised and widespread level. The aim of this study was
to explore the relationship between the measurement of
pain thresholds by two different QST methods and the
measurement of pain severity by a validated PROM.
Methods
Patients on the waiting list for a total knee replacement
because of osteoarthritis were approached about this study,
and 107 patients attended a QST session. A digital alg-
ometer (Somedic) with a 1cm probe was used to assess
pressure pain thresholds (in kPa) three times at each site.
A MSA Thermotest (Somedic) was used to measure hot
pain thresholds (in Celsius) four times at each site. Pain
thresholds were tested at the painful knee and the pain-
free forearm. Self-reported pain severity was assessed using
the WOMAC questionnaire. Spearman-Rank Correlation
Coefficients (CC) were calculated to determine the strength
of correlation between pain thresholds and pain severity.
Results
Pain severity in the knee significantly correlated with
pressure pain thresholds at the knee (CC=0.275, p=0.005)
and the forearm (CC=0.208, p=0.03). No significant cor-
relation was found between pain severity in the knee and
heat pain thresholds at the knee (CC=0.118, p=0.236) or
the forearm (CC=0.134; p=0.173).
Conclusions
This study found a small but significant positive correla-
tion between self-reported knee pain severity and pres-
sure pain thresholds, but not heat pain thresholds. This
suggests that as pain worsens, patients become more sen-
sitive to pressure pain at the osteoarthritic knee and the
pain-free forearm. Increased pain sensitivity at a pain-
free distant body site, such as the forearm, suggests invol-
vement of the central nervous system and widespread
pain sensitisation. The addition of Algometry as an out-
come measure in clinical trials and pain studies could
improve understanding of the mechanisms contributing
to self-reported pain severity, by identifying the presence
and extent of pain sensitisation. We are currently using
QST in a large randomised controlled trial of pain con-
trol in arthroplasty (the APEX study), to explore the rela-
tionship between pain sensitisation and pain severity in
osteoarthritis patients, and the influence of pain sensitisa-
tion on outcomes after joint replacement.
Acknowledgements
The authors could like to thank the Bristol Orthopaedic Trust for funding the
purchase of the QST equipment, Professor Sarah Hewlett for input into
study design, and Dr Rachael Gooberman-Hill for her helpful comments on
the abstract.
Author details
1University of Bristol, Bristol, BS10 5NB, UK. 2University of the West of
England, Bristol, BS16 1QY, UK. 3Peninsula Medical School, Universities of
Exeter and Plymouth, PL6 8BU, UK.
Published: 13 December 2011
doi:10.1186/1745-6215-12-S1-A79
Cite this article as: Wylde et al.: Pain assessment: the relationship
between pain thresholds and pain severity in osteoarthritis. Trials 2011
12(Suppl 1):A79.
1University of Bristol, Bristol, BS10 5NB, UK
Full list of author information is available at the end of the article
Wylde et al. Trials 2011, 12(Suppl 1):A79
http://www.trialsjournal.com/content/12/S1/A79 TRIALS
© 2011 Wylde et al; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.


Pain assessment: the relationship between pain thresholds and pain severity in osteoarthritis

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Trials

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This is a n  Op e n  Acces s  doc u m e n t  dow nloa d e d  fro m  ORCA, Ca r diff U nive r si ty 'sins ti t u tion al r e posi to ry: h t t p s://o rc a .c a r diff.ac.uk/id/e p rin t/15 8 0 8 4/This  is t h e  a u t ho r’s ve r sion  of a  wo rk  t h a t  w as  s u b mi t t e d  to  / a c c e p t e d  forp u blica tion.Cit a tion  for  final p u blish e d  ve r sion:Wylde,  Vikki, Palm er, S h e a ,  Le a r m o n t h,  Ian  D a n d  Diep p e,  Pa ul 2 0 1 1.  Paina s s e s s m e n t:  t h e  r el a tions hip  b e t w e e n  p ain  t h r e s holds  a n d  p ain  s eve ri ty inos t eo a r t h ri tis.  Trials  1 2  (S1) , A79. 1 0.1 18 6/17 4 5-6 2 1 5-1 2-s 1-a 7 9  file  P u blish e r s  p a g e:  h t t p://dx.doi.or g/10.11 8 6/174 5-6 2 1 5-1 2-s 1-a 7 9< h t t p://dx.doi.o rg/10.11 8 6/17 4 5-6 2 1 5-1 2-s 1-a 7 9 >Ple a s e  no t e:  Ch a n g e s  m a d e  a s  a  r e s ul t  of p u blishing  p roc e s s e s  s uc h  a s  copy-e di ting,for m a t ting  a n d  p a g e  n u m b e r s  m ay no t  b e  r eflec t e d  in t his  ve r sion.  For  t h ed efini tive  ve r sion  of t his  p u blica tion,  ple a s e  r ef e r  to  t h e  p u blish e d  sou rc e.  Youa r e  a dvise d  to  cons ul t  t h e  p u blish e r’s ve r sion  if you  wish  to  ci t e  t his  p a p er.This ve r sion  is b ein g  m a d e  av ailable  in  a cco r d a n c e  wit h  p u blish e r  policie s.S e e  h t t p://o rc a .cf.ac.uk/policies.h t ml for  u s a g e  policies.  Copyrigh t  a n d  m o r al  r i gh t sfor  p u blica tions  m a d e  available  in ORCA a r e  r e t ain e d  by t h e  copyrig h thold e r s .POSTER PRESENTATION Open AccessPain assessment: the relationship between painthresholds and pain severity in osteoarthritisVikki Wylde1*, Shea Palmer2, Ian D Learmonth1, Paul Dieppe3From Clinical Trials Methodology Conference 2011Bristol, UK. 4-5 October 2011ObjectivesWhen pain is assessed in research, it is most commonlyassessed using patient-reported outcome measures(PROMS). These measures can provide informationabout pain severity, distress and qualities, but they areunable to provide information about the underlyingmechanisms contributing to pain perception. Quantita-tive Sensory Testing (QST) comprises non-invasive testswhich can identify abnormalities in pain processing on alocalised and widespread level. The aim of this study wasto explore the relationship between the measurement ofpain thresholds by two different QST methods and themeasurement of pain severity by a validated PROM.MethodsPatients on the waiting list for a total knee replacementbecause of osteoarthritis were approached about this study,and 107 patients attended a QST session. A digital alg-ometer (Somedic) with a 1cm probe was used to assesspressure pain thresholds (in kPa) three times at each site.A MSA Thermotest (Somedic) was used to measure hotpain thresholds (in Celsius) four times at each site. Painthresholds were tested at the painful knee and the pain-free forearm. Self-reported pain severity was assessed usingthe WOMAC questionnaire. Spearman-Rank CorrelationCoefficients (CC) were calculated to determine the strengthof correlation between pain thresholds and pain severity.ResultsPain severity in the knee significantly correlated withpressure pain thresholds at the knee (CC=0.275, p=0.005)and the forearm (CC=0.208, p=0.03). No significant cor-relation was found between pain severity in the knee andheat pain thresholds at the knee (CC=0.118, p=0.236) orthe forearm (CC=0.134; p=0.173).ConclusionsThis study found a small but significant positive correla-tion between self-reported knee pain severity and pres-sure pain thresholds, but not heat pain thresholds. Thissuggests that as pain worsens, patients become more sen-sitive to pressure pain at the osteoarthritic knee and thepain-free forearm. Increased pain sensitivity at a pain-free distant body site, such as the forearm, suggests invol-vement of the central nervous system and widespreadpain sensitisation. The addition of Algometry as an out-come measure in clinical trials and pain studies couldimprove understanding of the mechanisms contributingto self-reported pain severity, by identifying the presenceand extent of pain sensitisation. We are currently usingQST in a large randomised controlled trial of pain con-trol in arthroplasty (the APEX study), to explore the rela-tionship between pain sensitisation and pain severity inosteoarthritis patients, and the influence of pain sensitisa-tion on outcomes after joint replacement.AcknowledgementsThe authors could like to thank the Bristol Orthopaedic Trust for funding thepurchase of the QST equipment, Professor Sarah Hewlett for input intostudy design, and Dr Rachael Gooberman-Hill for her helpful comments onthe abstract.Author details1University of Bristol, Bristol, BS10 5NB, UK. 2University of the West ofEngland, Bristol, BS16 1QY, UK. 3Peninsula Medical School, Universities ofExeter and Plymouth, PL6 8BU, UK.Published: 13 December 2011doi:10.1186/1745-6215-12-S1-A79Cite this article as: Wylde et al.: Pain assessment: the relationshipbetween pain thresholds and pain severity in osteoarthritis. Trials 201112(Suppl 1):A79.1University of Bristol, Bristol, BS10 5NB, UKFull list of author information is available at the end of the articleWylde et al. Trials 2011, 12(Suppl 1):A79http://www.trialsjournal.com/content/12/S1/A79TRIALS© 2011 Wylde et al; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative CommonsAttribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction inany medium, provided the original work is properly cited.

Wylde Vikki

Palmer Shea

Learmonth Ian D

Dieppe Paul

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Pain assessment: the relationship between pain thresholds and pain severity in osteoarthritis

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