The relationship between regional pain with or without neuropathic symptoms and chronic widespread pain

Objective: Test whether the risk of developing chronic widespread pain (CWP) in those with regional pain was augmented in those with symptoms of neuropathic pain (NP).

Methods: 1162 persons free of CWP completed the Douleur Neuropathique 4 (scores ≥3 indicating NP); demographics; Hospital Anxiety and Depression (HAD) scale; Pittsburgh Sleep Quality Index; pain medications. Participants were classified as having no pain, regional pain with no symptoms of NP ((NP) ̅), or regional pain with symptoms of (NP). At 12-month follow-up participants with CWP were identified. Logistic regression estimated the odds ratio (OR), with 95% confidence intervals (CI), of CWP in the (NP) ̅ and NP groups compared to no pain, and (NP) ̅ compared to NP. Partial population attributable risks (PARp) estimated the proportion of CWP attributable to baseline (NP) ̅ or NP exposure.

Results: 1162 participants completed the baseline DN4 and provided pain data at follow up: 523 (45.0%) had no baseline pain, 562 (48.4%) (NP) ̅ and 77 (6.6%) NP. 153 (13.2%) had CWP at 12 months: 19 (3.6%) no pain, 108 (19.2%)( NP) ̅, and 26 (33.8%) NP. (NP) ̅ (2.9 (1.9,4.3) and NP (2.1 (1.1,4.0)) predicted CWP after adjusting for demographics, HAD, PSQI, and medications. The PARp was 41.3% (25.2,54.0) for (NP) ̅ and 6.0% (0.1,11.6) for NP. The NP group were not more likely to develop CWP when compared directly to (NP) ̅ (1.5 (0.8,2.8)).

Conclusion: NP was relatively rare and predicted a small number of new onset CWP cases. Using these estimates, treatments targeting NP would at best prevent 6% of CWP cases.