Validation of the Rheumatic Disease Comorbidity Index

Abstract

Objective. There is no consensus on which comorbidity index is optimal for rheumatic health outcomes research. We compared a new Rheumatic Disease Comorbidity Index (RDCI) with the Charlson-Deyo Index (CDI), Functional Comorbidity Index (FCI), Elixhauser Total Score (ETS), Elixhauser Point System (EPS), and a simple comorbidity count (COUNT) using a US cohort of rheumatoid arthritis (RA) patients. Methods. Using administrative diagnostic codes and patient self-reporting, we tested predictive values of the RDCI, CDI, FCI, ETS, EPS, and COUNT for 2 outcomes: all-cause mortality and physical functioning. Indices were compared using 3 models: bare (consisting of age, sex, and race), administrative (bare plus visit frequency, body mass index, and treatments), and clinic (administrative plus erythrocyte sedimentation rate, nodules, rheumatoid factor positivity, and patient activity scale). Results. The ETS and RDCI best predicted death, with FCI performing the worst. The FCI best predicted function, with ETS and RDCI performing nearly as well. CDI predicted function poorly. The order of indices remained relatively unchanged in the different models, though the magnitude of improvement in Akaike's information criterion decreased in the administrative and clinic models. Conclusion. The RDCI and ETS are excellent indices as a means of accounting for comorbid illness when the RArelated outcomes of death and physical functioning are studied using administrative data. The RDCI is a versatile index and appears to perform well with self-report data as well as administrative data. Further studies are warranted to compare these indices using other outcomes in diverse study populations.

Lower education and living in countries with lower wealth are associated with higher disease activity in rheumatoid arthritis: results from the multinational COMORA study

“…Furthermore, data on past and currently present comorbidities were collected, namely presence of ischaemic cardiovascular disease (myocardial infarction, stroke), cancer (colon, skin, lung, breast and uterus for women, prostate for men, and lymphoma), gastrointestinal diseases (diverticulitis, ulcers), infections (hepatitis), lung disease (chronic obstructive pulmonary disease and asthma) and psychiatric disorders (depression). Based on this information, Rheumatic Disease Comorbidity Index was computed 15 16. This includes respiratory diseases, myocardial infarction, hypertension, diabetes, depression, ulcers or other gastrointestinal infections, fractures and cancer.…”

In wealthier countries, patients perceive worse impact of the disease although they have lower objectively assessed disease activity: results from the cross-sectional COMORA study

“…From information on comorbidities the Rheumatic Diseases Comorbidity Index (RDCI) was computed 2 12 13…”

CS-31 Safety of hydroxychloroquine withdrawal in older adults with systemic lupus erythematosus

“…Peter Izmirly*, 1 Nicole Bornkamp, 1 Anna Zezon, 1 Chung-E Tseng, 1 H Michael Belmont, 2 Anca Askanase, 3 Jane E Salmon, 3 Michael D Lockshin, 1 Jill P Buyon. 1 Background Although hydroxychloroquine (HCQ) is a mainstay of treatment for patients with Systemic Lupus Erythematosus (SLE), ocular toxicity can result from accumulated exposure.…”

“…1 Background Although hydroxychloroquine (HCQ) is a mainstay of treatment for patients with Systemic Lupus Erythematosus (SLE), ocular toxicity can result from accumulated exposure. The introduction of highly sensitive tools has engendered even more concern.…”