Multimorbidity and Hospital-related Outcomes in Patients with Rheumatoid Arthritis: A Cross-sectional Study

Multimorbidity is frequent in rheumatoid arthritis (RA) and is associated with increased mortality, impaired quality of life, and complex clinical management. However, its association with hospitalization characteristics, particularly hospital length of stay and reasons for admission, remains insufficiently characterized.

We conducted a five-month cross-sectional study (February to July 2024) in a tertiary university hospital, including adult patients diagnosed with rheumatoid arthritis according to the 2010 ACR/EULAR classification criteria. Multimorbidity was defined as the presence of at least two chronic comorbid conditions (CHCs), and patients were stratified into two categories: multimorbid (MMG) and non-multimorbid (N-MMG) groups. Data collected included demographic characteristics, clinical features, laboratory parameters, and imaging findings. Functional impairment was assessed using the Health Assessment Questionnaire (HAQ).

The study included 126 individuals with a mean age of 56.6 ± 13.4 years, of whom 84.9% were female. Multimorbidity was present in 52.4% of cases. Patients in the MMG were significantly older than those in the N-MMG (62.1 ± 9.9 vs 50.5 ± 14.2 years, p < 0.001). They also had significantly higher disease activity (DAS28, p < 0.001) and more impaired functional status as measured by HAQ (p < 0.001). Length of hospital stay was significantly longer in the multimorbid group. A hospital stay of 14 days or more was observed in 31% of MMG patients compared with 10.3% in the N-MMG cohort. Multivariate logistic regression analysis revealed that increasing age (OR = 1.11, 95% CI: 1.05-1.17, p < 0.001) and current corticosteroid use (OR = 4.73, 95% CI: 1.73-12.95, p = 0.002) were independently associated with multimorbidity. In addition, multimorbidity remained independently associated with prolonged hospitalization after adjustment for age, disease duration, disease activity, and corticosteroid use (adjusted OR = 3.42, 95% CI: 1.36-8.60; p = 0.009).

In this study, multimorbidity was associated with greater clinical complexity among hospitalized patients with RA and with less favorable hospital-related outcomes, particularly longer hospitalization duration. The higher disease activity and poorer functional status observed among multimorbid patients may partly explain the longer hospital stays observed.

Our findings indicate that multimorbidity is associated with a more complex clinical profile in hospitalized patients with rheumatoid arthritis and with poorer hospital-related outcomes, particularly prolonged length of stay. These associations may partly reflect the higher disease activity and greater functional impairment observed among multimorbid patients.