INTRODUCTION: Patients with clinically suspect arthralgia (CSA) have, according 
to their rheumatologists, an increased risk of rheumatoid arthritis (RA), but 
their actual outcome is unexplored. This longitudinal study investigated (1) 
progression from CSA to clinically detectable arthritis and (2) associations of 
clinical factors, serological factors (among which are anticitrullinated peptide 
antibodies (ACPAs)) and MRI-detected subclinical inflammation with arthritis 
development.
METHODS: 150 patients with CSA were followed for ≥6 months. At baseline, 
clinical and serological data were collected and unilateral 1.5 T-MRI of 
metacarpophalangeal (MCP), wrist and metatarsophalangeal (MTP) joints was made. 
MRI scoring was done according to the RA MRI scoring system. Subclinical MRI 
inflammation was defined based on MRI results of 193 symptom-free persons.
RESULTS: During follow-up (median=75 weeks, IQR=41-106 weeks), 30 patients 
developed clinical arthritis; 87% did so <20 weeks after inclusion. In 
multivariable analyses, age, localisation of initial symptoms in small and large 
joints (compared with small joints only), C-reactive protein level, 
ACPA-positivity and subclinical MRI inflammation significantly associated with 
arthritis development; ACPA and MRI inflammation were most strongly associated 
(HR (95% CI) respectively, 6.43 (2.57 to 16.05) and 5.07 (1.77 to 14.50)). After 
1-year follow-up, 31% of the patients with MRI inflammation and 71% of the 
ACPA-positive patients with MRI inflammation had progressed to arthritis. 
Forty-three per cent of the patients that developed arthritis within 1 year were 
ACPA-negative; 78% of them had subclinical MRI inflammation at baseline. When 
MRI inflammation was absent arthritis development was infrequent (6% in all 
patients with CSA and 3% in ACPA-negative patients with CSA).
CONCLUSIONS: Subclinical MRI inflammation precedes clinical arthritis with a few 
months. Subclinical MRI inflammation is, independent of other factors such as 
ACPA, associated with arthritis development.