Medicine

Painful truths: McGill Scale alone underestimates neuropathic pain in osteoarthritis patients

This post originally appeared on Medical News Bulletin.

New research published in The Archives of Physiotherapy suggests that doctors might be underestimating the amount of pain osteoarthritis patients experience.1

Osteoarthritis is a painful and debilitating condition. We usually associate it with pain caused by wear and tear on tissue – mechanical damage. This, however, isn’t the only type of pain experienced by osteoarthritis patients.  Patients who have osteoarthritis often experience neuropathic (nerve) pain in addition to chronic mechanical pain. Even after joint replacement therapy intended to alleviate chronic pain, up to 28% of patients continue to experience chronic pain. 

Researchers from Western University, Canada and McMaster University, Canada  investigated whether the methods doctors use to measure discomfort in osteoarthritis patients identify the true extent of their pain.1

They propose that:

1. the commonly used McGill Pain questionnaire may not accurately capture or address the sensations experienced in neuropathic pain and

2. that osteoarthritis patients should be assessed using the NP-MPQ (SF2) subscale (Neuropathic subscale of the McGill pain questionnaire) in addition to the routine scale. 

 The McGill Pain Scale, also known as the McGill Pain Questionnaire (MPQ) is the standard for measuring pain. It uses a variety of phrases to describe various aspects of pain, such as “throbbing,” “pulsing,” or “stinging”. Users can choose the terms that best describe their experience from a variety of categories, including sensory, affective and evaluative. While these descriptors work well for pain caused by mechanical damage, they do not always reflect the sensation of neuropathic pain.

Neuropathic pain is a chronic pain condition caused by problems with, or damage, to the nervous system. It is different from regular pain that results from injuries or inflammation because it originates from abnormal nerve signals.

In order to test whether the Neuropathic subscale of the McGill questionnaire  (NP-MPQ (SF2)) could help doctors to better treat osteoarthritis patients suffering with neuropathic pain, they compared it to another pain rating system known to catch more cases of neuropathic pain.  Over a period of six years, researchers identified individuals who had reported severe pain either six months or one year after their surgery and whose pain remained the same or got worse compared to before the surgery.1 These participants were sent a mail-in survey containing two questionnaires: the NP-MPQ(SF-2) and the S-LANSS questionnaire. 

 The study found that the NP-MPQ (SF-2) subscale accurately distinguished between neuropathic pain (NP) and non-neuropathic pain after joint replacement surgery. They compared it to the S-LANSS as a reference standard. However, both scales still missed some patients with NP features, so further comparison to expert clinician diagnosis is needed. 

These results emphasize the importance of improved monitoring and early detection of neuropathic pain in osteoarthritis patients. While these scales may not capture all types of neuropathic pain, they represent a positive step toward improving chronic pain management.

References

  1. Boljanovic-Susic D, Ziebart C, MacDermid J, de Beer J, Petruccelli D, Woodhouse LJ. The sensitivity and specificity of using the McGill pain subscale for diagnosing neuropathic and non-neuropathic chronic pain in the total joint arthroplasty population. Arch Physiother. 2023;13(1):9. doi:10.1186/s40945-023-00164-7

This post originally appeared on Medical News Bulletin.