Comparison of Pain Characteristics in Patients with Rheumatoid Arthritis and Systemic Sclerosis with Particular Reference to the Neuropathic Pain Component: Cross-Sectional Study

Objective: The aim of the study was to compare characteristics of pain in terms of neuropathic pain (NeP) and to assess the association between the neuropathic component and quality of life (QoL) in patients with systemic sclerosis (SSc) and rheumatoid arthritis (RA). Subjects and Methods: Fifty-four patients (47 females, 7 males) with SSc and 53 patients (46 females, 7 males) with RA were assessed for outcome measures including disease activity, physical functions, mental condition and health-related QoL (HRQoL) measures (Short Form-36; Hospital Anxiety and Depression Scale), and pain. NeP was assessed by the Douleur Neuropathique 4 (DN4) and PainDetect questionnaires in this cross-sectional study. Results: The patients had similar education, smoking status, functioning, and HRQoL. However, the patients with RA declared a more severe visual analogue scale of pain and a higher BMI than those with SSc. The NeP component was detected in 42.6% (n = 23) of the SSc patients and in 45.3% (n = 24) of the RA patients (p > 0.05) according to DN4. On PainDetect, possible NeP was detected in 13.0% (n = 7) versus 15.1% (n = 8), whereas 16.7% (n = 9) versus 17.0% (n = 9) were likely to have NeP in SSc and RA, respectively (p > 0.05). Most of the NeP characteristics were similar in SSc and RA, except for numbness and painful cold, which were notably more common in patients with SSc. Having the NeP component (according to DN4) had no influence on functioning and HRQoL in SSc; however, the NeP component revealed a heavier burden of disease regarding functional status, HRQoL, and psychometric components in RA. Conclusion: The NeP component was similar between patients with SSc and RA. However, NeP was associated with a heavier burden of disease in patients with RA.