When do you consider referral to hand surgery for management of joint deformity in RA?

This is individualized to the patient's needs. If a patient is uncomfortable due to pain, quality of life or lack of function due to the deformity, I would arrange a consultation with a hand surgeon. Some patients do get distressed by the cosmetic appearance of the deformities and this is an indication for referral as well. There is a paucity of long-term published outcomes data for this but the following article from 2018 did cite good 10-year outcomes: Okura C et al., PMID 30187667. In general...

I agree with Dr. @Dr. First Last that the decision has to be individualized for each patient. As a rheumatologist, our main goal is to prevent hand (and other) joint deformities, but alas, sometimes the disease takes its course despite our best efforts. Some patients livelihood depends on hand, or wrist function, and if medications and splints cannot alleviate this, hand surgery is a good option. I would emphasize to the patient that I will continue to work hard with them to prevent deformities ...