Curtis JR, et al. - Researchers undertook this study to develop an age-adjusted comorbidity index (AACI) to predict, using baseline characteristics, the serious infectious event (SIE) risk in patients with rheumatoid arthritis (RA) treated with certolizumab pegol (CZP). In this population, SIE risk was strongly predicted by AACI and glucocorticoid use, at baseline. There was no relation between predicted SIE risk and patients’ likelihood of clinical response. Overall, these data indicate that this SIE risk score may have clinical utility, as a tool to detect the risk of infection in individual patients with RA.