Patients With vs Without Rheumatoid Arthritis Have Higher Prevalence of Multimorbidity

Researchers assessed the multimorbidity burden in patients with rheumatoid arthritis to determine the multimorbidity definition for research and clinical practice.

Compared with individuals without rheumatoid arthritis (RA), those with RA have a higher prevalence of multimorbidity, according to study results published in RMD Open.

Researchers aimed to compare multimorbidity burden in patients with RA vs those without RA.

Researchers conducted a population-based study among residents of 8 counties in Minnesota. Data from patients with prevalent RA on January 1, 2015, were identified and age-, sex-, and county-matched with individuals without RA.

Morbidities were defined using 2 codes that were 30 or more days apart, 44 previously defined morbidities and 78 nonoverlapping chronic disease categories, based on Clinical Classification Software. Multimorbidity was defined as having 2 or more morbidities. Prevalence of morbidities in the RA and non-RA groups were adjusted for multiple comparisons using false discovery rate; the morbidities that were more common in patients with RA vs those without RA and those with a prevalence of 5% or more were considered in the current analysis.

Overall, 1643 patients with RA and 1643 individuals without RA were included in the study. The mean age of participants was 63.1 years and 72% were women.

Based on the 44 previously defined morbidities, 1411 (86%) participants in the RA and 1164 (71%) in the non-RA group were diagnosed with multimorbidity (P <.001). The presence of 5 or more morbidities occurred in 907 (55%) individuals in the RA and 619 (38%) in the non-RA (P <.001) group. Researchers noted a significantly higher prevalence of 24 of the 44 morbidities (odds ratio, >2.9) among patients with RA, especially those with interstitial lung disease, fibromyalgia, osteoarthritis, and osteoporosis.

Including only the 78 secondary morbidities, 433 (26%) participants in the RA and 292 (18%) in the non-RA group were diagnosed with 2 or more morbidities, and 46 (3%) and 18 (1%) participants, respectively, were diagnosed with 5 or more morbidities. Of the 78 morbidities, 7 were significantly higher in the RA than the non-RA group, including organic sleep disorders, vitamin D deficiency, and foot ulcers.

Study limitations included the use of diagnostic codes, the retrospective study design, the limited diversity of the study population, and that the severity and impact of morbidities on outcomes were not assessed.

According to the researchers, “This comprehensive assessment of morbidities in RA can help to unify the literature on multimorbidity to help move this field forward.”


Crowson CS, Gunderson TM, Dykhoff HJ, et al. Comprehensive assessment of multimorbidity burden in a population-based cohort of patients with rheumatoid arthritis. RMD Open. 2022;8(1):e002022. doi:10.1136/rmdopen-2021-002022