Fig. 1

Current and previous administrative divisions of Jeju Island. The cross indicates the location of Jeju regional rheumatoid and degenerative arthritis center. The previous and current administrative districts are as indicated below. A: previous Jeju city district B: previous North Jeju County district C: previous Seogwipo City district D: previous South Jeju County district A and B: current Jeju city district C and D: current Seogwipo city district