Multimorbidity is frequent in rheumatoid arthritis (RA) and could interfere with the therapeutic response. The aim of this study was to evaluate multimorbidity in the French cohort of early arthritis, the ESPOIR cohort, and its possible impact on the therapeutic response.

We included patients fulfilling 2010 ACR/EULAR criteria for RA. An adapted MultiMorbidity Index (aMMI) was developed. Each patient was assigned scores of binary aMMI (0=no comorbidity, 1=at least 1 comorbidity) and counted and weighted aMMI. The primary endpoint was achievement of Clinical Disease Activity Index (CDAI) low disease activity after initiation of a first disease-modifying antirheumatic drug (DMARD) according to the aMMI. We collected data from the visit preceding the first DMARD initiation and the visit after at least 3 months of treatment. The impact of aMMI on therapeutic maintenance at 1, 3, 5 and 10 years was evaluated.

Analyses involved 472 patients: 302 (64%) had at least 1 comorbidity. Overall, 45.3% and 44.7% with binary aMMI=0 or 1, respectively (non-significant), achieved CDAI low disease activity. Similar results were found with counted and weighted aMMI. Therapeutic maintenance was significantly better with binary aMMI=1 than binary aMMI=0 (OR at 10 years=14.0 [CI 95% 3.3–59.4]). Increased counted aMMI was associated with increased probability of still being on the first initiated DMARD at each time point.

In the ESPOIR cohort, therapeutic response to a first DMARD was not affected by multimorbidity but therapeutic maintenance was better in multimorbid patients.