Background/Purpose

Patients with rheumatoid arthritis (RA) experience chronic management issues and are at risk for complex comorbidities. It is unknown, however, to what extent the complications of the disease may lead to hospitalization. The goal of this study is to discern whether patients with RA are at greater risk for all-cause hospitalizations when compared to the general population.

Methods

This retrospective, population-based cohort study utilized patients who were 18 years or older and diagnosed with RA (as defined by the 1987 ACR criteria) between 1/1/1980 and 12/31/2007, and a reference cohort of patients without RA matched on age, sex, and calendar year. Each patient’s medical record was examined for hospitalizations from 1987 through 2012. For this analysis, follow-up began with the latter of index date or 1/1/1987 and ended at the earlier of death, last follow-up or 12/31/2012. Discharge diagnoses were grouped together using the Clinical Classifications Software for ICD-9-CM from Healthcare Cost and Utilization Project. Data were analyzed using person-year methods and rate ratios comparing RA to non-RA.

Results

The 799 RA and 797 non-RA cohorts each consist of patients with a mean age of 56 years (68% female) and a mean follow-up of 12 years and 13 years respectively. The patients with RA had 2968 hospitalizations and the non-RA patients had 2069 hospitalizations. RA patients proved to be at greater risk for all causes of hospitalization (Table 1). Increased risk for all-cause hospitalizations for patients with RA also held true for both sexes and all age groups.

Two discharge diagnoses are of interest. First, hospitalization for depression is a greater risk for male patients with RA (23 hospitalizations) than for the general male population (3 hospitalizations) (Rate Ratio [RR] 7.16, 95% Confidence Interval [CI] 2.78, 30.67). Second, patients with RA are at greater risk of hospitalization for diabetes (31 hospitalizations) than patients without RA (13 hospitalizations) (RR 2.45, CI 1.34, 4.89). Female patients with RA are at a significantly increased risk of hospitalization for diabetes (16 hospitalizations) when compared to the general female population (6 hospitalizations) (RR 2.65, CI 1.14, 7.45). An increased risk of hospitalization for diabetes is especially true for all RA patients age 45-64 (22 hospitalizations) when compared to the general population (0 hospitalizations) (RR 44.76, CI 8.32, 45072.3).

Conclusion

In this first ever analysis of all-cause hospitalizations in a population-based cohort, patients with RA appear to be at greater risk for hospitalization than patients without RA. This risk is true for both sexes and all age groups. RA patients are also markedly more likely to be hospitalized for depression if they are male. Furthermore, hospitalization for diabetes is prevalent among patients with RA, especially among females and patients in the 45-64 age group.

*Rate of hospitalizations per 100 person-years