469 C-REACTIVE PROTEIN LEVELS ARE ASSOCIATED WITH OA-RELATED KNEE PAIN IN WOMEN

Purpose: Pain is the most common, disabling symptom for people with Osteoarthritis (OA).Cumulative data suggests dysfunctional pain processing by the central nervous system, called central sensitization (CS), contributes to pain in OA.CS can be associated with the neuropathic pain (NP) symptom profile including burning, electric-shock like sensations, and sensitivity to light touch.Improved understanding of pain mechanisms in OA, including development of "clinically feasible" tools to identify individuals likely to have CS would facilitate development of novel mechanism-based pain therapies.This ongoing study is assessing (1) NP symptoms in subjects with symptomatic knee OA, using a NP questionnaire modified for use in OA, the modified painDETECT (mPD-Q), and the Self-completed Leeds Assessment of Neuropathic Symptoms and Signs pain scale (S-LANSS), which has been validated in other chronic pain populations; (2) pain intensity, using the Von Korff Chronic Pain Grade Scale (CPG) and, (3) co-morbid chronic pain and neurological conditions.Methods: Eligible study subjects are members of an existing populationbased OA cohort with chronic symptomatic knee OA defined by pain, discomfort and/or stiffness in the knee(s) on most days for 3 months.A standardized questionnaire was mailed to 268 cohort members to date, to assess (1) pain quality for each knee using the mPD-Q, scored -1 to 38; and the S-LANSS, scored 0-24; (2) pain intensity, using the CPG, scored 0-100; and (3) co-morbid conditions.Mean, median, and standard deviation (SD) were evaluated for questionnaire scores.The proportion of knee OA cohort participants with mPD-Q and S-LANSS scores in the 'NP range' (mPD-Q score 19, S-LANSS score 12) was calculated using a 95% confidence interval.Pearson correlations between mPD-Q and other questionnaire scores (SLANSS and CPG) were examined.Results: To date, 129 (48%) questionnaires have been returned.Thirtytwo (29%) responders reported no chronic knee pain.Among 92 (71%) responders with chronic knee pain, 73 had chronic right and 63 had chronic left knee pain.Mean (SD) mPD-Q scores were the same, 12 (7), for right and left knees.Mean (SD) S-LANSS scores were 8 (8) for right knees and 7 (7) for left knees.According to cut-points identified in other pain populations, the proportion (95% CI) of study subjects with scores in the 'NP range' on the mPD-Q was 0.21 (0.12-0.32) for right knees and 0.17 (0.08-0.28) for left knees; on the S-LANSS was 0.31 (0.20-0.42) for the right knees and 0.25 (0.14-0.36) for left knees.The mPD-Q scores had a moderate to high correlation with the S-LANSS scores for right (r = 0.68) and left knees (r = 0.73).The mPD-Q scores had a moderate correlation with CPG pain intensity scores for right (r = 0.61) and left (r = 0.65) knees.The following factors did not explain the variability seen in mPD-Q scores: presence of diabetes, another chronic pain condition, a co-morbid neurological condition.Conclusions: In a population-based cohort with chronic knee OA, almost a quarter of subjects with painful knee OA scored in the 'NP range' on both of the measures assessed.This subgroup of patients may benefit from further evaluation for NP likely due to CS and consideration of NP medications.Further validation work on the mPD-Q is ongoing.