Background/Purpose: Ankylosing Spondylitis (AS) usually affects young males, severely impairing their quality of life. Chronic treatment of AS using anti-TNF α agents is costly and represents a main concern for the national health insurance system, currently covering costs for three drugs: Adalimumab (ADA), Etanercept (ETA) and Infliximab (INF). Limited budget prompted the need to find optimal therapeutic approach. We aimed to identify the best cost/efficiency ratio when comparing clinical outcomes of anti-TNF α agents ADA/ETA/INF and to develop future treatment guidelines.

Methods: In a longitudinal, population-based study we retrospectively investigated, as of June 2012, the clinical files of 320 patients treated with ADA (n=70, 40 mg/2 weeks), ETA (n=50, 50 mg/week) and INF (n=200, 5 mg/kg at week 0, 2 and 6 then at every 6 to 8 weeks), out of 1859 AS patients on record in database (2008-2012) of state health insurance system. Costs were calculated in local currency (RON), according to standard clinical practice prescribed doses and reimbursed drug list prices, no infusions or other additional costs were included. We used multiple analysis of variance (MANOVA) and chi-squared tests to analyze statistically significant differences (p<0.05) in treatment efficacy.

Results: Concomitant use of disease modifying therapy (DMARD) was similar in all groups. Treatment efficacy was assessed and compared using Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), tender joints count (TJC) and swollen joints count (SJC), C Reactive Protein (CRP) and Erythrocyte Sedimentation Rate (ESR). Assessments were made at 6 month intervals over a maximum period of 54 months after treatment initiation. In our nationally representative cohort, 266 (83.1%) patients were male. Overall, mean age was 37.4±9.8 years and average disease evolution 7.6±6.1 years. Sacroiliitis was present in 34 (10.6%) patients, calcaneum was affected in 45(14.1%), as confirmed on MRI scans, 27(8.4%) showed ophthalmic symptoms of autoimmune disease, 188 (58.8%) suffered from axial AS and 132 (41.2%) were diagnosed with mixed AS. Median baseline BASDAI values were 8.02±0.78, 8.07±0.92 and 8.13±0.82, in ADA, ETA and INF groups, respectively. We found statistical difference (p<0.0001) in CRP values at 6 months from baseline, but no difference at any other assessment. Similarly, there were no statistically significant differences between groups at any assessments for ESR, TJC and SJC. In contrast, drug cost analysis showed INF as the most expensive followed by ADA and by ETA.

 

anti-TNF α agent	Median price (RON)	Difference vs. most expensive (%)	Average price (RON)	Difference in average price (all patients) vs. average price per therapy (%)
INF	58.933	0	65.195	8.36
ADA	52.248	-12.80	52.248	-14.34
ETA	48.420	-21.71	48.420	-23.38

1 USD = 3.5766 RON

Conclusion: For the vast majority of endpoints, including BASDAI index, there were no statistically significant differences in treatment efficacy between the investigated groups at any assessment. Therefore, we suggest that treatment cost, rather than active compound, might be taken into consideration when choosing between these three anti-TNF α drugs for treatment of autoimmune AS.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-burden-of-ankylosing-spondylitis-and-the-cost-effectiveness-of-anti-tumor-necrosis-factor-%ce%b1-agents-in-romania/