Comparison of Indexes to Measure Comorbidity Burden and Predict All-Cause Mortality in Rheumatoid Arthritis

Abstract

Objectives: To examine the comorbidity burden in patients with rheumatoid arthritis (RA) patients using a nationwide population-based cohort by assessing the Charlson Comorbidity Index (CCI), Elixhauser Comorbidity Index (ECI), Multimorbidity Index (MMI), and Rheumatic Disease Comorbidity Index (RDCI) scores and to investigate their predictive ability for all-cause mortality. Methods: We identified 24,767 RA patients diagnosed from 1998 to 2008 in Taiwan and followed up until 31 December 2013. The incidence of comorbidities was estimated in three periods (before, during, and after the diagnostic period). The incidence rate ratios were calculated by comparing during vs. before and after vs. before the diagnostic period. One- and 5-year mortality rates were calculated and discriminated by low and high-score groups and modified models for each index. Results: The mean score at diagnosis was 0.8 in CCI, 2.8 in ECI, 0.7 in MMI, and 1.3 in RDCI, and annual percentage changes are 11.0%, 11.3%, 9.7%, and 6.8%, respectively. The incidence of any increase in the comorbidity index was significantly higher in the periods of “during” and “after” the RA diagnosis (incidence rate ratios for different indexes: 1.33–2.77). The mortality rate significantly differed between the high and low-score groups measured by each index (adjusted hazard ratios: 2.5–4.3 for different indexes). CCI was slightly better in the prediction of 1- and 5-year mortality rates. Conclusions: Comorbidities are common before and after RA diagnosis, and the rate of accumulation accelerates after RA diagnosis. All four comorbidity indexes are useful to measure the temporal changes and to predict mortality.

Association between Rheumatic Disease Comorbidity Index and factors of poor prognosis in a cohort of 280 patients with rheumatoid arthritis

“…Comorbidities may precede or appear during the course of the disease. Some studies noted that the burden of comorbidity is common before and after RA diagnosis, and the rate of accumulation accelerates after RA diagnosis [ 21 , 22 ]. Our results were close to the reported scores of RDCI in RA [ 14 , 21 ].…”

“…Some studies noted that the burden of comorbidity is common before and after RA diagnosis, and the rate of accumulation accelerates after RA diagnosis [ 21 , 22 ]. Our results were close to the reported scores of RDCI in RA [ 14 , 21 ]. In this study, hypertension was the most common comorbidity as it has been reported in other studies [ 3 , 15 ].…”

“…However, depression is commonly associated with disability [ 11 ]. The impact of comorbidities on RA outcomes is rarely studied using validated instruments such as the RDCI [ 13 , 21 ].…”

Clinical Features Associated With Rate of Fractures in Patients With Systemic Sclerosis: A US Cohort Study

“…RDCI. We used patient-reported data to evaluate the burden of comorbidity across 11 comorbid conditions outlined in previous studies (19,20). Conditions included ulcer or stomach problem, hypertension, myocardial infarction, other cardiovascular disease (e.g., heart failure), lung disease, diabetes mellitus, depression, cancer, stroke, and fracture (i.e., spine, hip, or leg).…”

“…Conditions included ulcer or stomach problem, hypertension, myocardial infarction, other cardiovascular disease (e.g., heart failure), lung disease, diabetes mellitus, depression, cancer, stroke, and fracture (i.e., spine, hip, or leg). The index was calculated based on the presence and severity of coexisting comorbid conditions, with impact assessed using 6 outcomes that were weighted as described in previous studies (15,19). The RDCI ranges from 0 to 9 and assesses quality of life and the anticipated effects of comorbidities on functional disability and mortality.…”