Background After over a decade of use of biological agents (BA), is widely known to be effective in the treatment of Rheumatoid Arthritis (RA). With the increasingly widespread use of these drugs, a thorough knowledge of their long-term behavior is fundamental.
Objectives To evaluate survival of BA, as well as causes of discontinuation, in a cohort of elderly patients with RA.
Methods We conducted a retrospective longitudinal observational study of 13 years follow-up. Subjects: RA patients followed in our out-patient clinic, which started treatment with BA at ages over 65 years old, between January 1st 2000 and November 18th 2013. Primary endpoint: discontinuation of BA (etanercept (ETN), golimumab (GOLI), certolizumab (CTZ), infliximab (IFX) and adalimumab (ADA); other biological: rituximab (RTX), abatacept (Fold), tozilizumab (TZL)) due to: a) adverse event (AE) (moderate: suspension of the drug regardless of the impact; severe: suspension and hospitalization or death); b) inefficacy; c) decision of the patient; d) remission or improvement, e) other. Secondary variables: sociodemographic (age, sex); clinical (duration of illness, type of BA). Analysis: description of sociodemographic and clinical characteristics of patients included and the reasons of discontinuation with frequency distribution, and the mean and standard deviation. The exposure time was defined from the start date of each BA to the date of discontinuation, loss of follow-up or end of the study. Discontinuation rates of BA by survival techniques, expressing the incidence per 100 patients * year with their respective 95% confidence interval (95% CI).
Results 146 patients with RA were included in the study, which began 286 different courses of treatment with BA, follow-up was 604.5 patients * year. Of these, 78% were women with a mean age at diagnosis of 66.5±7 years and a median time to the start of the first BA of 6±5 years. The most frequently used drug was ADA (27.3%), followed by IFX (22.4%), ETN (21.3%) and RTX (19.2%). 24% of patients continued treatment at the time the end of monitoring. We found 199 discontinuations in 87 patients: 21.7% due to inefficacy, 39% to EA (6% exitus), 2.8% to patient choice and 2.8% to improvement. The median survival of BA was 1.7 years (95% CI 1.2 to 1.9), with an incidence of discontinuation of 33 (95% CI 28.6 to 37.8). The incidence of discontinuation by BA is shown in the table. The discontinuation rate due to AE was 18.4 (95% CI 15.2 to 22.1). The discontinuation rate due to inefficacy was 10.3 (95% CI 8 to 13.5) and to improvement was 1.3 (95% CI 0.66 to 2.64).
Conclusions After 2 years of treatment, half of patients over 65 have discontinuated BA due to different reasons. Discontinuation rate is estimated at 33 per 100 patient * year, the most frequent cause being inefficacy, followed by AE. This study contributes to increasing knowledge of long-term survival of these drugs in RA patients over 65 years and in real life.
Disclosure of Interest None declared