Multimorbidity May Increase Risk, Duration of Hospitalization for Patients With RA

Having additional long-term conditions puts patients with rheumatoid arthritis (RA) at a higher risk of hospitalization, found researchers of a new study published in Seminars in Arthritis and Rheumatism, which revealed that hospital stays were also longer for these patients.

With 60% to 75% of patients with RA developing other long-term conditions throughout their lifetime, the researchers underscored the importance of using multimorbidity in risk stratification of patients with RA based on their findings.

The study included over 5000 patients with established RA from the UK Biobank and early RA from the Scottish Early Rheumatoid Arthritis (SERA) cohort. Patients with additional long-term conditions, particularly those with established RA, were more likely to be hospitalized and to be hospitalized for a longer time than patients with RA alone and patients without RA. Across all patients with RA, inflammatory arthritis was a common reason for hospitalization.

Among patients with established RA, those with 2 or more additional long-term conditions had a hospitalization rate that was 2.10 times higher than that of patients with RA alone (331 vs 160 per 1000 patient-years). Osteoarthritis was among the top 2 reasons for hospitalizations among these patients, regardless of the number of additional long-term conditions, which the researchers explained was likely resulting from joint damage due to longstanding RA.

Hospitalization duration was 2.48 times higher among patients with RA plus 2 other long-term conditions than among patients with RA alone (2182 vs 955 days per 1000 patient-years). Similarly, the frequency of hospitalizations and duration of stay were higher for patients with established RA than for patients without RA who had an equivalent number of long-term conditions.

Among patients with early RA, who were more likely to be hospitalized for respiratory infection, the hospitalization rate was 1.74 times higher among those with 2 or more additional long-term conditions than those with RA alone (382 vs 182 per 1000 patient-years), and hospital duration was 1.9 times higher among patients with RA plus two or more other long-term conditions than among patients with RA alone (2379 vs 812 days per 100 patient-years).

The prevalence of long-term conditions tended to be higher among patients with established RA. For example, comorbid hypertension—the most common long-term condition—was significantly higher among established patients than among patients with early RA (35.8% vs 21.2%). Painful conditions (18.6% vs 10.5%), asthma (14.9% vs 8.5%), and dyspepsia (11.2% vs 4.2%) were also more prevalent among patients with established RA compared with patients with early RA. Rates of thyroid conditions, chronic heart disease, diabetes, and depression were comparable between the 2 groups of patients.

“Prevalence of multimorbidity in those with RA was in line with what has previously been reported for UK Biobank, but slightly lower in SERA,” wrote the researchers. “It may be that additional [long-term conditions] are still to develop in SERA participants due to this being a younger inception cohort, such that the condition itself or treatments used for RA have not yet impacted, or, as has been previously reported, that conditions such as hypertension and depression may be underdiagnosed in early RA when the clinical focus is on controlling RA disease activity.”

Reference

Morton F, Jani B, Mair F, et al. Association between risk, duration and cause of hospitalisations in people with rheumatoid arthritis and multimorbidity in the UK Biobank and Scottish Early Rheumatoid Arthritis (SERA) cohorts: longitudinal observational study. Semin Arthritis Rheum. Published online November 17, 2022. doi:10.1016/j.semarthrit.2022.152130