A study was carried out to investigate the frequency of subclinical skin inflammation in both hands by fluorescence optical imaging (FOI) in patients with psoriasis/psoriatic arthritis (Pso/PsA) vs. rheumatoid arthritis (RA) and healthy individuals, and to correlate these findings with cardiovascular (CV) risk factors.
The FOI scans were analyzed retrospectively to detect clinically invisible skin enhancement (0–3 scale) in both hands without relationship to underlying joints or blood vessels. The FOI patterns were characterized and scans were sorted into groups based on the assumed diagnosis (Pso/PsA, RA, and healthy controls), which was compared with the physician’s diagnosis. Furthermore, the associations between CV risk factors and imaging findings were investigated by regression analyses.
FOI scans of patients with Pso/PsA (n =?80), RA (n =?78), and healthy controls (n =?25) were included. Subclinical skin enhancement on the back of their hands was more common in Pso/PsA (72.5%) than in RA patients (20.5%) and healthy individuals (28.0%). Based on the FOI pattern, the majority of patients with Pso/PsA (72.5%), RA (76.9%), and healthy controls (68.0%) were classified correctly using the physician-based diagnosis as reference (overall agreement of 74%). No CV risk factors except body weight (kg) were associated with subclinical skin enhancement.
Subclinical subdermal skin inflammation was common in Pso/PsA patients using FOI and were classified with the correct diagnosis. An important influence of the body weight on FOI results were demonstrated. FOI may be a helpful novel tool to study microcirculation in rheumatic diseases with the skin involvement.