There was a time when unless tissue damage could be seen on X-ray or scan, pain was thought to be either imaginery or ‘psychogenic’. As time has gone on, it’s more common than not to read that people have chronic pain (such as neuropathic pain) that is present without evidence on some sort of imaging, and that psychosocial factors influence how much that pain presents as a problem for the person.
Sadly, the converse is not true – when degenerative changes are found on, for example, a hip joint or a knee joint, the patient and doctor rejoice! ‘Aha!’ they say, ‘We’ve found the problem, let’s cut that bit out, put a new one in – and voila! No more pain, no more problem.’ Oh but if only that were the case…
The problem is that even when pathology is present, it’s happening to a person – and that person is responding to and living within a context of beliefs and attitudes that influence how the person expresses his or her pain. In a health system where funding is limited, the level of disability a person displays is often used to determine whether surgery will proceed. Disability is all about how a person responds to and lives with his or her tissue-based limitations. Attitudes and beliefs that are present before surgery are almost certainly still there after surgery, so are highly likely to influence recovery.
This study by Somers, Keefe and Pells et al. (2008) explores the influence of pain catastrophising and pain-related fear/anxiety on walking speed in a group of people with osteoarthritis of the knee. The authors used walking speed because it is one of the key areas of disability for people with OA of the knee, and they also studied obese patients because as a group, they present with more pain and more disability than people with a BMI of less than 24.
‘The inclusion criteria for the study were: Patients were included if
1) they reported knee pain on most days of the month for at least the prior six months,
2) were overweight or obese (BMI between 25 and 42 kg/m2),
3) met the American College of Rheumatology criteria for OA and had radiographic evidence of OA affecting one or both knees,
4) had no other major weight-bearing joint affected by OA, and
5) if OA of the knee(s)was the medical condition that contributed most to limitations in their daily function.
They were excluded if they
1) they had a significant medical condition that increased their risk of a significant adverse health event during physical activity (e.g., myocardial infarction in the previous six months, an abnormal cardiac response to exercise, such as exercise-induced BT, or abnormal blood pressure),
2) had another known organic disease that would contraindicate safe participation in the study,
3) had a non-OA inflammatory anthropathy/ another arthritic disorder (e.g., rheumatoid arthritis),
4) engaged in regular oral corticosteroid use, or
5) already were involved in a regular exercise or weight loss program.’ (Quoted directly so as to be accurate!)
106 participants were recruited mainly from Rheumatology, Orthopedic Surgery, and Pain Management clinics at Duke University Medical Center, and via community newpapers and were aged 58.7 years (SD=9.2), and 77% were female. The average BMI in this group was 34.7 (SD=1.0), and their disease rating (Kellgren-Lawrence OA disease rating) was 2.8 (SD=1.0).
The ‘catastrophising’ subscale of the Coping Strategies Questionnaire (Rosenstiel & Keefe, 1998) was used to measure catastrophising, this has six items, with a six-point scale (0 – 6) anchored with never and always, that ask patients to rate the frequency with which they engage in catastrophizing when they experience pain.
The Tampa Kinesiophobia Scale (Kori, Miller & Todd, 1990) (17 item version) was used to measure fear of movement, this version has 17 items scored on a 4-point scale from ‘‘strongly agree’’ to ‘‘strongly disagree.’’
The Arthritis Impact Measurement Scale (Meenan, Gertman, & Mason, 1980) is a 45 item self-report questionnaire measuring general health status in people with arthritis. It has three sub-scales: pain, psychological disability, and physical disability, that are summed to create a total score.
Gait analysis was conducted to measure changes in gait pattern and velocity at three different speeds. They were normal walking speed, fast walking speed, and intermediate walking speed, described as ‘the speed they would normally perform their daily walking activities (normal), the maximum speed they felt comfortable achieving (fast), and a speed in between those two speeds (intermediate).’
5 trials for each participant were conducted and recorded and analysed using AMTI force plates and EvaRT software to analyse the movement patterns recorded from reflective markers on bony landmarks on each participant.
So you can see it wasn’t an easy undertaking – lots of data analysis! It is nice to see a comparison between self-report and live functional measures.
I’ll cut to the chase to summarise the findings relevant to the main hypotheses:
‘1. That both pain catastrophizing and pain-related fear would be related to pain severity, psychological disability, physical disability, and gait velocity assessments (e.g.,walking speeds) after controlling for demographic and medical status variables.
2. That catastrophizing would be more strongly related to pain severity and psychological disability, and
3. That pain-related fear would be more strongly related to physical disability and gait velocity assessments (e.g., walking speeds).’
Pain catastrophising explained much of the variance in pain (10%), psychological disability (20%), physical disability (11%), and walking at all speeds (4%).
Pain-related fear also explained a good deal of the variance in measures of psychological disability (7%) and walking at fast speed (5%).
These two were predictive after controlling for demographic and medical factors that are usually thought to predict disability. In fact, they were so strongly related, that the authors point out these two variables had more effect than all the other usually identified variables put together. So, it seems important that these two factors are measured and managed when working clinically with people with OA knee. Somehow I don’t think this happens routinely here in New Zealand – yet.
The hypotheses that pain catastrophising would explain more of the variance in psychological measures, and fear of pain in functional measures was also confirmed. Pain catastrophising, the authors suggest, may influence processing of nociception, and may well influence neural processes related to pain perception.
Pain-related fear didn’t explain a significant proportion of variance in self-reported physical disability in OA patients, whereas pain catastrophizing did. This suggests that tendencies to ruminate on pain and feel helpless in the face of pain (e.g., pain catastrophizing) may be more important in explaining physical disability in persons with OA than pain-related fear. What this means clinically is that it may be less helpful to use a behavioural approach (eg graded exposure to activities) than a cognitive restructuring approach to reduce the brooding, worrying and sense of helplessness these people experience.
So maybe, rather than simply encouraging people to attend an exercise class under the supervision of a physiotherapist, it may be more helpful to use a cognitive behavioural approach and help people to develop specific strategies to develop more helpful thoughts and beliefs. It might also help post-operatively if the person goes on to have total knee replacement, because I’m sure their catastrophising will also be present when they experience acute postsurgical pain – so it may help speed up their rehabilitation. Again, to my knowledge this approach doesn’t happen in New Zealand hospitals.
Currently, people who are proceeding to total knee surgery are routinely assessed functionally, their BMI is measured, and they are provided with support to change their diet, and to exercise. I don’t think anxiety, catastrophising or fearfulness of pain are either measured or managed. Given the results from this study, which is consistent with similar studies in other diagnoses, I wonder if surgeons, anaesthetists, physiotherapists, occupational therapists and others might start to consider working with the ‘other’ parts of the person than simply their knee. It might save both surgery waiting lists, and time in hospital and recovering afterward – all for the sake of a couple of questionnaires and clinical time from therapists skilled in cognitive behavioural therapy.
T SOMERS, F KEEFE, J PELLS, K DIXON, S WATERS, P RIORDAN, J BLUMENTHAL, D MCKEE, L LACAILLE, J TUCKER (2008). Pain Catastrophizing and Pain-Related Fear in Osteoarthritis Patients: Relationships to Pain and Disability Journal of Pain and Symptom Management DOI: 10.1016/j.jpainsymman.2008.05.009
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