The nerve of osteoarthritis pain

Abstract

Cumulative data suggest that central sensitization may contribute to pain in osteoarthritis (OA) and present with symptoms typically associated with neuropathic pain (NP). We evaluated the responses from focus group participants on the knee OA pain experience for pain descriptions that suggest NP. Focus group transcripts were analyzed by 2 independent assessors for unprompted use of pain descriptors that suggested NP. Items from validated NP symptom-based questionnaires were used to guide the analysis. Data on sociodemographic factors, duration of knee OA, and OA disease and pain severity (using the Western Ontario and McMaster Universities Osteoarthritis Index and a numerical rating scale) were obtained from questionnaires administered after focus group completion. These factors were compared among participants who did and did not use descriptors that suggested NP. Transcripts from 80 knee OA participants were analyzed. A range of NP descriptors was used to characterize their knee symptoms, including burning, tingling, numbness, and pins and needles. The proportion of participants who used NP descriptors was 0.34 (95% confidence interval 0.24-0.45). Those who used NP descriptors were younger (P = 0.003) and, although not statistically different, more likely to be women, with higher pain intensity and OA severity and longer OA duration, than those who did not use NP descriptors. During focus groups, a subset of adults with chronic, symptomatic knee OA used pain quality descriptors that were suggestive of NP. Elicitation of NP descriptors in people with OA may help identify those who could benefit from further evaluation and perhaps treatment for NP.