The following is a summary of “Application of the grading system for “nociplastic pain” in chronic primary and chronic secondary pain conditions: a field study,” published in the August 2024  issue of Pain by Schmidt et al.

Nociplastic pain was developed for patients with nociceptive system sensitization that nociceptive or neuropathic mechanisms could not explain.

Researchers conducted a retrospective study to test how effectively the recently published grading system differentiated chronic primary and secondary pain conditions.

They evaluated patients with fibromyalgia (FMS, n = 41), complex regional pain syndrome (CRPS, n = 11), osteoarthritis (OA, n = 21), or peripheral nerve injury (PNI, n = 8), using clinical history, pain drawings, quantitative sensory testing (QST), and questionnaires to classify the pains as possibly or probably neoplastic. All patients with chronic primary pain had widespread/regional pain not explained by either of the mechanisms. 

The results showed that widespread pain occurred in 12 patients with OA but was identified as nociceptive in 11 of the 12. Regional pain was present in 4 patients with PNI and was recognized as neuropathic in 3 of the 4. At this stage, the grading system demonstrated 100% sensitivity and 93% specificity. Clinical evidence for pain hypersensitivity, as assessed by QST, and a history of hypersensitivity and mental comorbidities did not differentiate between chronic primary pain (QST: 36/52 = 69%, history: 43/52 = 83%) and secondary pain conditions (QST: 20/29 = 69%, history: 24/29 = 83%). Although the specificity remained excellent (93%), sensitivity dropped substantially to 60% due to the lack of evidence for pain hypersensitivity in many patients with FM; this low sensitivity in the grading system suggested its unsuitability for screening purposes.

They concluded that structural and content modifications were needed to improve sensitivity, including placing patient history before the clinical examination and adding a high tender point count as evidence for widespread pain hypersensitivity.

Source: journals.lww.com/pain/fulltext/9900/application_of_the_grading_system_for__nociplastic.695.aspx