Characteristics and long-term outcomes of patients with rheumatoid arthritis and concurrent calcium pyrophosphate...

To compare the characteristics, treatment patterns, and long-term outcomes of patients with concurrent calcium pyrophosphate deposition disease (CPPD) and rheumatoid arthritis (RA) to patients with RA without CPPD.

We studied patients with RA from the Veteran's Affairs RA (VARA) registry and identified patients with CPPD using administrative codes. We compared characteristics of patients with concurrent CPPD and RA to those with RA alone at enrollment. We used parsimonious multivariable logistic regression to study the probability of achieving a low disease activity as well as receiving prednisone and new biologic or targeted synthetic disease modifying antirheumatic drugs (b/tsDMARDs) over follow-up, adjusting for pre-hypothesized confounders and stratifying by autoantibody status.

Among 2771 U.S. veterans with RA, we identified 64 (2.3 %) patients with CPPD at enrollment. Patients with CPPD were older [68.5 (9.0) v. 64.2 (11.0), p < 0.001], had higher rates of comorbidities, including osteoarthritis (93.8 % v. 80.1 %, p = 0.007), spine disease, and diabetes, and were less likely to have ACPA (63.5 % v. 77.8 %, p = 0.01). While those with CPPD were numerically less likely to achieve low disease activity over time, this was not statistically significant. Among seronegative patients, CPPD patients exhibited more prednisone use (OR 2.44 [95 % CI 1.15-5.22]) and more frequent initiation of b/tsDMARDs (OR 2.79 [95 % CI 1.46-5.32]) as well as higher rates of joint replacement and death during follow-up.

Seronegative RA patients with CPPD changed therapies more frequently, used more prednisone, and had worse long-term outcomes. These findings suggest some seronegative RA may represent CPPD and require alternative diagnostic and treatment approaches.