Background/Purpose: Biologics have constituted a major advance in the treatment of RA, PsA and AS. In Norway access to these therapies has been good since their introduction. With increasing focus on early and aggressive therapy, one could expect increasing use of biologics, including use in patients (pts) with moderate disease activity. The objectives were to examine if prescription rates of biologics in RA, PsA and AS continue to increase or have reached a plateau, and whether disease activity at initiation of therapy has changed over the years.

Methods: Data for this study were from the NOR-DMARD register. Prescriptions of biologics to biologics naïve pts with RA, PsA and AS between Jan 2002 and Nov 2011 in 4 centers covering regions in East- and Mid-Norway were studied. Population data were extracted from Statistics Norway (www.ssb.no). Prescription rates per 100,000 inhab. per year were calculated and adjusted for an estimated 15% incompleteness of the register. Numbers were also adjusted for incomplete data for 2 centers in 2002 and all centers in 2011. Further, we calculated rates as % of pts, based on published Norwegian disease prevalence data [0.45% for RA (2 studies), 0.20% for PsA, 0.26% for AS]. Baseline (BL) disease activity [CRP, DAS28 and ASDAS (from 2006)] was examined per diagnosis per year. Potential effects of prescription year were assessed by linear regression with BL variables as the dependent variable and year as a continuous (1-10) independent variable. CRP was Ln-transformed for the analyses.

Results: The material included 1961 prescriptions – 1026 in RA, 375 in PsA and 560 in AS. These were all TNF inhibitor (TNFi) prescriptions in AS, 2 non-TNFi in PsA and 38 non-TNFi in RA (32 rituximab, 3 abatacept, 3 tocilizumab). The population in the study area increased from 1.31 mill to 1.44 mill from 2002 to 2011. Prescription rates per year are shown in Table 1. There was a trend towards increasing prescription rates in AS throughout the study period. Fluctuations in the annual prescription rates were observed for RA and PsA. First biologic was since 2007 prescribed more frequently in AS and PsA together than in RA. (Table 1). BL levels of disease activity measures decreased significantly over time in all 3 diagnoses (Table 2).

Conclusion: The annual rate of first-time prescriptions of biologics to patients with RA, PsA and AS increased from 15 per 100,000 in 2003 to 25 per 100,000 in 2011. During recent years the increase was most pronounced in AS and prescriptions were more frequent in AS and PsA combined than in RA. Baseline disease activity levels at the start of treatment decreased gradually in all diseases, with a marked reduction in patients with RA.