Systemic and local factors are involved in the evolution of erosions in hand osteoarthritis

<h3>Objective</h3> In order to gain insight in the pathogenesis of erosive hand osteoarthritis (OA), the evolution of erosions in hand OA and risk factors involved were investigated. <h3>Methods</h3> The 6-year evolution in radiographic Verbruggen–Veys anatomical phase was assessed in interphalangeal joints of 236 patients with hand OA (mean age 59 years, 83% women) from the GARP (for 'Genetics ARthrosis and Progression') sibling pair study. Erosive evolution comprised phase transitions from non-erosive to erosive phases and from active erosions to remodelling. Clustering of erosive evolution within patients was assessed using the χ² test. Familial aggregation was evaluated in sibling pairs by estimating ORs for siblings and probands sharing erosive evolution. Local baseline determinants and the effect of high sensitivity C reactive protein were assessed using generalised estimating equations. <h3>Results</h3> Erosive evolution took place in 181 of 4120 interphalangeal joints at risk (4.4%), corresponding to 60 patients (25.4% of study sample). Erosive evolution was found more often in multiple interphalangeal joints in one patient than would be expected by chance (χ² 373.0, p&lt;0.001). The adjusted OR (95% CI) for a sibling having erosive evolution if the proband had erosive evolution was 4.7 (1.4 to 15.8). Systemic inflammation was not associated with erosive activity. Independent local determinants were joint space narrowing (OR (95% CI) 8.9 (4.8 to 16.4)) and self-reported pain (OR (95%CI) 2.3 (1.1 to 4.7)). <h3>Conclusions</h3> Erosive evolution was clustered within patients and families. Local factors were also involved in the evolution. This increase in insight in the pathogenesis of erosive hand OA will contribute to the development of new treatments.