Who develops chronic pain...and why??

Let's say you have two people who walk into your clinic with an acute episode of back pain after they fell off their bikes in very similar ways. Their pain location is the same as is their initial pain intensity. Both seemed to have muscle strains after physical assessment. After a few sessions, patient A is doing much better...pain is down and he is well on his way to a full recovery. On the other hand, patient B seems to be doing worse...pain is not going away and it's starting to affect other aspects of daily life. This is peculiar to you because both had very similar objective findings when they first arrived to see you and both sustained very similar
injuries....what gives?!?!

This brief and overly simplistic story is common. The question that has been on my mind for the last several months has been what factors predispose one person to have chronic pain and another person to get better in a matter of weeks? Why do similar injuries lead to often very different outcomes despite good care?  What traits or factors do different people posses that lead them down the wrong road into the land of chronic pain?

In the world of social media where rehab gurus rein supreme, I would expect that some "expert" would give an intricate pathoanatomical explanation as to why patient B didn't get better. I might hear such things as I should assess their rolling pattern, or that a certain muscle has become inhibited in the (insert random body part here). I would be told that I need to take this or that course to learn the next "game changer" technique to be better at my job. While con-ed is great and learning from peers online has been a blessing for me, I would say that what is not talked about are the less sexy causes for pain...the stuff we can't assess with a movement screen or strength test.

I took a course a few weeks ago by a professor out of Western University that addressed the prognostic factors that lead to chronic spinal pain. Dr. Dave Walton might not be a social medial celebrity in the world of rehab/therapy, but that's probably because he is too busy conducting real research out of his lab, The Pain and Quality of Life Integrative Research Lab.  This course, entitled "Prognosis- based approach to assessment and treatment of acute neck and low neck pain" was a 1 day seminar discussing the evidence behind the very question I ask on a daily basis....what causes chronic pain?

We talked about the roughly 25% of people who suffer an acute injury that becomes chronic and what similarities they had.  For whiplash:

High confidence of risk factors for chronicity	High confidence of no effect on outcomes
High pain intensity >6/10	Angular deformity of the neck
High neck-related disability	Impact direction
Post-traumatic stress symptoms	Seating position
Catastrophizing	Awareness of collision
Cold hypersensitivity	Head rest in place
Mechanical hypersensitivity (distal >local)	Older age
	Vehicle speed

(Walton et al. 2013)

I find it funny that many of the more anatomical categories such as position of neck and impact direction have very little to do with the onset of chronic pain. This continues to beg the question of the relevance of biomehanics in the treatment of the chronically pained patient.

For lower back pain, the results of a large scale meta-analysis from 2010 by Chou and Shekelle,  which was published in JAMA showed the following

Current evidence for LBP

Strong evidence of risk	Moderate evidence of risk	No clear evidence of risk
Nonorganic signs (Waddell’s signs)	Non-supportive work environment	History of prior LBP
Maladaptive coping behaviours	High baseline pain	Demographics (age, sex)
High self-report functional impairments (e.g RMQ)	Presence of radiculopathy
Presence of psychiatric comorbidities
Low general health status

The conclusion of this article stated:

The most helpful components for predicting persistent disabling low back pain were maladaptive pain coping behaviours, nonorganic signs, functional impairment, general health status, and presence of psychiatric comorbidities.

The other key aspect of this course was the introduction of evidence backed outcome measures for pain and disability. These are used so we can actually measure objective change in pain and disability over time without the subjective conjecture of "oh you're getting stronger and moving much better". Having validated measures to use such as the Brief Illness Perceptions Questionnaire, the LEFS or Neck Disability Index (NDI) are great ways of helping us get a clearer picture of the patients pain and how it specifically effects their day to day life. It also helps us understand the patients beliefs around their pain and why they think they have it and how optimistic they are about recovery. Knowing this information going into an initial assessment really helps me get a clear picture of what I need to do with the patient. Maybe they believe their doomed to lifetime pain or maybe they have very few yellow flags. Knowing this drastically changes how I communicate and even what I do with the patient on the initial visit.

Overall, my tune has changed quite a bit over my 5 years of practice in that I used to be very quick to label peoples pain as anatomy related..."your back pain is due to your locked S.I joint or you have a twisted pelvis creatng muscle spasm". I now cringe at thinking all the ways I scared patients and made them feel fragile and broken. As it stands now, my practice strives to rule out the bad reasons for pain (the red flags) and to find ways of modifying my patients pain to hopefully help them see that they have the ability to get better without excessive treatment. Education is a cornerstone of my practice...sometimes I think I talk TOO much to my patients about how robust their bodies are!

To hear from a physiotherapist I strive to emulate please take the time to  watch this interview from Prof. Peter O'Sullivan, a world renowned expert in treating chronic pain:
https://www.youtube.com/watch?v=YWGSdRGQG-M