Background Significant pain persists in a substantial proportion of Rheumatoid Arthritis (RA) patients in spite of disease remission. Recent evidence indicates that features suggestive of neuropathic pain (NP) are present in RA patients with a prevalence range of 33–38% using the painDETECT questionnaire (PDQ).
Objectives To estimate the clinical predictors of NP in a cohort of RA patients.
Methods Observational, cross-sectional study was performed with RA patients followed at our Rheumatology department with unchanged DMARD treatment during the last 3 months. Patients with diagnosed neuropathy or non-RA risk factors for NP were excluded. Selected patients were evaluated in a medical visit. Demographic, clinical and laboratorial data were collected and disease activity and functional measures were evaluated. Two questionnaires were applied to assess NP: the Leeds Assessment of Neuropathic Symptoms (LANSS) and the PDQ. Univariate and multivariate logistic regression were performed to identify the predictors of NP. Significance level was set as <0.05.
Results 112 RA patients were included. 86 (77%) were females, with a mean (SD) age of 55.1 (10.8) years and median disease duration of 13 years (range: 2–41). 84% patients were seropositive for Rheumatoid Factor and/or ACPA. 102 (91%) were treated with DMARDs and 42% with a biologic DMARD, whom 8% in monotherapy. The mean (SD) DAS28 4V was 3.61 (1.01) and 12% were in remission. 45 (40%) patients had NP by the LANSS (≥12), 28% had a possible/likely NP in the PDQ (>12) and 21% were positive in the both tests. Female sex was predictive of LANSS and PDQ NP (OR: 3.44, p=0.02 and OR: 3.70; p=0.05, respectively) and disease duration was a predictor of LANSS (OR: 0.92 per year, p=0.004). After adjusting for these variables, pain VAS, patient global activity and the tender joint count were positive predictors of NP by both tests. Swollen joint count, ESR or CRP levels were not significantly associated with NP. DAS28 CRP and HAQ scores were both significant positive predictors of PDQ NP (OR: 1.77 and OR: 3.61, p<0.01, respectively). DAS28 CRP, dichotomized as remission/non-remission, and the HAQ score were also significantly positive predictors of LANSS NP (OR: 5.55, p=0.01 (DAS28 CRP≥2.6); OR: 2.15, p=0.03). Positivity for ACPA was a negative predictor of LANSS NP (OR: 0.23, p=0.009), remaining significant after adjusting for DAS28 CRP, HAQ and current methotrexate (MTX). Number of analgesics and current NSAIDs treatment were associated with PDQ NP (OR: 2.72 and OR: 3.40, respectively, p<0.05). Current MTX and previous/current Hydroxychloroquine (HCQ) treatment were both negative predictors for PDQ NP (OR: 0.41 and OR: 0.20, respectively, p<0.05). No other significant associations were found. In a subgroup with dosed TSH levels (n=18), there was a positive though non-significant association with LANSS and PDQ (OR: 3.12, OR: 14.98, p=0.09).
Conclusions NP was present in sizable proportion of RA patients. Consistently with previous data, our study supports the association between NP and disease activity/functional scores but not with objective inflammatory measures. This study newly points to a possible protective role of ACPA positivity, MTX and HCQ treatment in NP risk.
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AW Christensen et al. Scand J Rheumatol 2016;1–9.
Disclosure of Interest T. Martins Rocha Grant/research support from: Portuguese Society of Rheumatology/Alfa Wassermann on May 2015, S. Pimenta: None declared, M. Bernardes: None declared, A. Bernardo: None declared, M. Barbosa: None declared, R. Lucas: None declared, L. Costa: None declared