10 - Patterns and predictors of dosage increase in patients treated with adalimumab for Crohn's disease in the United States

Abstract

s of the 4th Congress of ECCO the European Crohn’s and Colitis Organisation S7 the Poisson regression, for CD and UC. A spatial analysis, with Bayesian approach was then performed. Results: From January 1, 2000 to December 31, 2002, 14,213 new patients with CD (8,172 women) and 12,452 new patients with UC (5,984 women) were registered by the five health insurance funds, among the overall insured population of 58,157,661. There was a significant negative correlation between age and gender-adjusted CD incidence rates, and local UV dose (IRR = 1.42, 95%CI [1.27 1.58] for the first quintile, IRR = 1.12, 95%CI [1.00 1.26] for the second quintile, IRR = 0.90, 95%CI [0.78 1.04] for the third quintile, IRR = 0.85, 95%CI [0.74 0.98], for the fourth quintile (fifth quintile = reference). Local UV dose improved the Bayesian model of geographic distribution of CD and the effect of local UV dose was stronger than the effect of local spatial autocorrelation. Variations of smoothed relative risks (sRR) of CD in both sexes according to the sunlight exposure are displayed in the figure. Areas with a sRR significantly higher than 1 corresponded to departments with low sunlight exposure, whereas those with high sunlight exposure had sRR either lower than 1 or not significantly different from 1. Conclusion: These results suggest that low sunlight exposure is a risk factor for CD. This hypothesis should be investigated within case-control or cohort studies. 10 Patterns and predictors of dosage increase in patients treated with adalimumab for Crohn’s disease in the United States E.V. Loftus Jr.1 *, X. Pan2, P. Zurawski3, P. Mulani3, J. Chao3. 1Miles & Shirley Fiterman Center for Digestive Diseases, Mayo Clinic, Rochester, MN, USA, 2University of Iowa, Iowa City, IA, USA, 3Abbott Laboratories, Abbott Park, IL, USA Introduction: Adalimumab, a fully human anti-tumor necrosis factor monoclonal antibody, is an effective treatment for Crohn’s disease (CD). After induction therapy, adalimumab 40mg is usually used as every-other-week dosing for maintenance therapy. In a large clinical trial, 27% of patients increased their adalimumab dosage to weekly within 1 year [1]. Information regarding the dosage pattern of adalimumab in real-world clinical practice is of interest. Our objective was to determine the dosage pattern of adalimumab in patients with CD covered by specialty pharmacies in the United States and to identify predictors for dosage increase to a weekly regimen. Methods: Using data from a large specialty pharmacydispensing database in the United States from March 2007 to July 2008, we studied patients with CD (ICD-9: 555) whose first dose of adalimumab was on or after 1 March 2007. New users of adalimumab were included in the analysis. Adalimumab maintenance therapy was defined as 3 dispensing events of adalimumab within 1 year. A weekly dosage regimen of adalimumab was defined as 2 consecutive weekly doses after the first dispensing event. Descriptive weekly dosing rates were determined by calculating the ratio of patients with weekly dosing to the total sample of adalimumab-treated patients. To control for the impact of variable follow-up times, Kaplan Meier analysis was used to estimate the weekly dosing rate for a 12-month period. To identify possible predictors for weekly dosing, a Cox proportional hazards regression model was developed to examine the impact of age, sex, geographic region, and use of a 160/80-mg induction dose on the weekly dosing rate. Results: Of 1335 patients with CD who received adalimumab as maintenance therapy, 11.3% (n = 151) had weekly dosing at any time during the study period. The 12-month cumulative risk of weekly dosing was 15.5% (Kaplan Meier analysis). The Cox proportional hazards model demonstrated that geographic region and not starting on 160/80mg for induction therapy were significant predictors for weekly adalimumab use. Patients who received 160/80mg as induction therapy were approximately half as likely to receive weekly dosing as those who didn’t start with 160/80mg (Hazards ratio [HR] = 0.48, 95%CI: 0.33 0.69, non-160/80-mg user as reference group, p < 0.0001). The western and southern regions of the United States had significantly lower rates of weekly dosing than did the northeastern region (HR = 0.50, 95%CI: 0.27 0.90 and HR= 0.46, 95%CI: 0.31 0.69, respectively, with northeast as reference group; both p < 0.05). Conclusions: The rate of adalimumab weekly dosing in clinical practice is less than the rates observed in clinical trials. Patients who received 160/80-mg induction therapy were significantly less likely to receive weekly dosing, and geographic variation in weekly adalimumab dosing rates was observed.