Erosive Hand Osteoarthritis: Incidence and Predictive Characteristics among Participants in the Osteoarthritis Initiative.

OBJECTIVE To evaluate age, sex, race, osteoarthritis severity, metabolic factors, and bone health as risk factors for incident erosive hand osteoarthritis (EHOA) at baseline and over 48-month period. METHODS This study was a longitudinal cohort design including participants from the Osteoarthritis Initiative with complete hand radiographs from baseline and 48-month visits who were eligible at baseline for incident EHOA. Individuals were classified as having EHOA if they had Kellgren-Lawrence (KL) grade≥2 in at least one interphalangeal joint on two different fingers and central erosion in at least one joint. RESULTS Of the 3365 individuals identified without prevalent EHOA at baseline, 86 (2.6%) developed EHOA during the 48-month period. Risk factors included being older [relative risk (RR) per standard deviation=0.76 (95% confidence interval 0.59, 0.98)], female [RR=1.73 (1.05, 2.85)], greater osteoarthritis severity (sum of KL grade 13.9 vs. 5.3, p<0.001) and less cortical width (1.38 vs 1.52 mm, p<0.001). After 48 months, people who developed EHOA were characterized by greater progressions of radiographic osteoarthritis (i.e., joint space narrowing, KL grade progression [RRs = 1.35 to 1.9] and loss of cortical thickness [RR = 1.23], adjusted for age, sex, race, body mass index, and baseline osteoarthritis severity (sum KL scores). CONCLUSION These findings present EHOA as a disorder of advanced age and female sex, strongly associated with severity of articular structural damage and its progression. Individuals who develop EHOA have thinner bones prior to EHOA development and as it progresses, suggesting EHOA as a disorder of skeletal frailty.