Previous studies have suggested a link between inflammation and central sensitization of pain in patients with RA. We conducted a prospective cohort study to determine whether US Doppler (USD), temporal summation (TS) of pain-assessed at baseline-and the potential interaction between them could predict the treatment response in RA.
Patients were recruited from Departments of Rheumatology in the Copenhagen area and from private clinics. RA patients, who were scheduled to initiate therapy with either a conventional synthetic DMARD (csDMARD; including DMARD-naïve patients) or a biologic DMARD (bDMARD) agent (including bDMARD switch), were included and examined before the start of treatment and after 4 months. During the 4 months, patients received routine care from their treating rheumatologist.
Multiple regression analysis was conducted, with change in DAS28 as the dependent variable. In unadjusted models, baseline USD score was significantly associated with DAS28 (β = 0.06; 95% CI: 0.02, 0.09; P < 0.001), whereas TS and their interaction were not. After adjusting for age, sex, disease duration, baseline DAS28 and whether patients initiated a csDMARD or a bDMARD, the USD score was still significantly associated with change in DAS28 (β = 0.032; 95% CI: 0.001, 0.064; P = 0.046), whereas TS remained insignificant.
USD assessed at baseline is valuable as a prognostic factor for change in disease activity in 'real-life' RA patients. We did not find evidence to suggest that TS or the interaction between USD and TS was prognostically important for this group of patients.