Background Rheumatoid Arthritis (RA) patients have increased risk of infection and comorbidities¹. Understanding healthcare resource utilization (HRU) and infection risk associated with comorbidity burden in RA may facilitate awareness of outcomes and development of care coordination strategies in RA.

Objectives To estimate the differences in HRU and odds of an all-cause infection claim in RA patients with comorbidities compared to RA patients without comorbidities.

Methods RA patients identified by ICD-9 CM codes (714.xx) were identified in a transactional U.S. healthcare claims database (Symphony Health) between years 2003 to 2013. RA patients with continuous clinical activity for 1 year after the first observed RA diagnosis (index date) were included. HRU and all-cause infection claim occurrence were measured 1 year post- index. The proportion of patients with ≥1 comorbidity (Comorbidity Cohort; CC) and those without any comorbidities (No Comorbidity Cohort; NC) were summarized using descriptive statistics. The odds of developing an infection and magnitude of HRU were estimated using multivariable logistic and gamma log-link regression models, respectively. Additional independent variables used in the models included age, gender, race, region, household income, medical payer and biologic medication use.

Results 645,158 RA patients were identified using the inclusion criteria (30% NC; 70% CC). The average age for the NC group was 56 years at RA index and 75% were female. The CC group was similar in age and gender –mean age was 58 years at RA index and 77% were female. On average, the CC group had 3 comorbidities per patient (range 1 to 18). CC patients with ≥4 comorbidities were more than 2 times as likely to have an infection claim compared to NC patients (p<.0001). Patients with ≥10 comorbidities had the highest odds ratio (OR) for an all-cause infection claim (9.81 OR p<.0001) compared to NC patients. The risk for an infection claim increases by an average of 61% for each additional comorbidity. Females were more likely to develop infection compared to males (1.41 OR p<.0001). Furthermore, the odds of an infection claim increased as comorbidity burden increased (p<.0001). Biologic use did not significantly increase the odds of an infection claim in CC patients when comorbidities were controlled for in the model (OR 1.01; p=0.1938). HRU models estimated that each additional comorbid condition was associated with approximately 43% higher total costs and 41% increase in outpatient days.

Conclusions Comorbidity burden in RA patients is associated with higher total healthcare resource and costs and higher odds of having a medical billing claim for infection. While controlling for comorbidity burden, biologic use did not significantly increase the odds of all cause infection healthcare claims.

1. Gullick, N.J., Scott, D.L. co-morbidities in established rheumatoid arthritis. Best Practice & Research Clinical Rheumatology 2011; 25: 469–483

Disclosure of Interest A. Teeple Employee of: Janssen Scientific Affairs, LLC, M. Ryan Consultant for: Janssen Scientific Affairs, LLC, L. Muirheid Consultant for: Janssen Scientific Affairs, LLC, L. Ellis Employee of: Janssen Scientific Affairs, LLC