Diagnosis of an inflammatory rheumatic disease (including rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, reactive arthritis, connective tissue diseases, Behçet disease, familial Mediterranean fever, or crystal arthropathies), confirmed by a rheumatologist
Healthy volunteers without a history of rheumatic or chronic inflammatory disease (for the control group)
Ability to undergo non-invasive skin autofluorescence measurement
Ability and willingness to provide written informed consent
You may not be if
Diagnosis of diabetes mellitus (type 1 or type 2)
Chronic kidney disease with estimated glomerular filtration rate (eGFR) \< 60 mL/min/1.73 m²
Active malignancy or history of malignancy within the past 5 years
Presence of acute infection or acute inflammatory condition at the time of assessment
Secondary causes of systemic inflammation unrelated to the underlying rheumatic disease (e.g., uncontrolled endocrine disorders, chronic liver disease)
Use of medications known to markedly affect AGE accumulation or skin autofluorescence measurements (e.g., recent high-dose systemic glucocorticoids)
Pregnancy or breastfeeding
Presence of significant skin conditions (e.g., extensive dermatitis, scars, tattoos, or burns) at the measurement site that may interfere with skin autofluorescence assessment
Inability to comply with study procedures or to provide informed consent
