Fluorescence optical imaging (FOI) enables visualization of inflammation in the hands in rheumatic joint diseases with currently a lack of long-term follow-up studies.
To investigate FOI for treatment monitoring in a homogenous cohort of patients with early (disease duration < 2 years) and active (DAS28 > 3.2) RA over a period of 12 months.
Thirty-five RA patients (24 (68.6%) females, mean age 53.3 years (SD 13.6)) were investigated clinically by DAS28, tender joint count (TJC) and swollen joint count (SJC) and by FOI in phases 1-3 and PrimaVistaMode (PVM) before therapy change and after 12 months. The FOI activity score (FOIAS) was calculated based on individual joint scores from 0 to 3 in 30 joints per patient, adding up to a sum score (0-90).
We found a statistically significant reduction of FOIAS in phase 1 from baseline (median 5.0, IQR 24.96) to follow-up (median 1.0, IQR 4.0) in all patients (p = 0.0045), both in responders and non-responders according to EULAR response criteria by DAS28. Statistically significant reductions over 12 months were found for median DAS28(ESR) 5.61 to 3.31, TJC 7.0 to 1.0, and SJC 5.0 to 1.0 (each p <  0.001). No statistically significant correlations were detected between the FOIAS change in phase 1 and DAS28(ESR), TJC, or SJC. Correlations between the other phases and clinical outcomes were weak to moderate.
Reduced early enhancement in FOI phase 1 can be observed in clinically responding and non-responding early RA patients under treatment. Regarding potential marker performance, FOI probably shows a reduction of inflammation more objectively.