A comparative study on clinical and serological characteristics between patients with rhupus and those with systemic lupus erythematosus and rheumatoid arthritis

Lupus. 2020 Sep;29(10):1216-1226. doi: 10.1177/0961203320938456. Epub 2020 Jul 6.


Background: The concomitant presence of two autoimmune diseases - systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) - in the same patient is known as rhupus. We evaluated a group of patients with rhupus to clarify further their clinical, serological and immunogenic features in a multi-centre cohort. In addition, the study aimed to explore the utility of the 2019 European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) SLE classification criteria in our group of patients with rhupus.

Methods: This was a cross-sectional study. We included rhupus patients from 11 different rheumatology departments, and compared them to SLE and RA patients at a ratio of 2:1. All information was recorded following a pre-established protocol.

Results: A total of 200 patients were included: 40 rhupus patients and 80 each of SLE and RA patients as controls. Disease duration was similar among SLE and rhupus groups (around 13 years), but the RA group had a significantly lower disease duration. Main clinical manifestations were articular (94.2%), cutaneous (77.5%) and haematological (72.5%). Rhupus patients had articular manifestations similar to those expected in RA. Only 10% of rhupus patients had renal involvement compared with 25% of those with SLE (p < 0.05), while interstitial lung disease was more common in patients affected by RA. The 2019 EULAR/ACR SLE criteria were met in 92.5% of the rhupus patients and in 96.3% of the SLE cohort (p > 0.05). Excluding the joint domain, there were no differences between the numbers of patients who met the classification criteria.

Conclusion: Rhupus patients follow a particular clinical course, with full expression of both SLE and RA in terms of organ involvement, except for a lower prevalence of kidney affection. The new 2019 EULAR/ACR SLE criteria are not useful for differentiating SLE and rhupus patients. A new way of classifying autoimmune diseases is needed to identify overlapping clusters.

Keywords: Arthritis; poly-autoimmunity; rheumatoid arthritis; rhupus; systemic lupus erythematosus.

Publication types

  • Comparative Study
  • Multicenter Study

MeSH terms

  • Adult
  • Aged
  • Arthritis, Rheumatoid / classification
  • Arthritis, Rheumatoid / immunology
  • Arthritis, Rheumatoid / physiopathology*
  • Case-Control Studies
  • Cross-Sectional Studies
  • Disease Progression
  • Female
  • Humans
  • Lupus Erythematosus, Systemic / classification
  • Lupus Erythematosus, Systemic / immunology
  • Lupus Erythematosus, Systemic / physiopathology*
  • Male
  • Middle Aged
  • Retrospective Studies

Supplementary concepts

  • rhupus syndrome