Background/Purpose:

Use of tumor necrosis factor inhibitors (TNFi) for ankylosing spondylitis (AS) is directed by national guidelines in the UK. However in the US, in the absence of treatment recommendations, the use of TNFi is dictated by local practice patterns.  We compared the use of TNFi in the treatment of AS at Aberdeen Royal Infirmary (ARI) in Scotland, and Oregon Health & Science University (OHSU) in Oregon. 

Methods:

This was a retrospective analysis of patients who were newly started on TNFi for treatment of AS between 2007 and 2012 at OHSU, and between 2004 and 2011 at ARI. Data on patient demographics, clinical characteristics and treatment were collected from electronic medical records. Descriptive analysis, Mann-Whitney U test and chi-square test (Fisher’s exact test if N <5) was used to compare the two groups of patients.

Results:

There were significant differences between the 2 groups regarding age, HLA B27 positivity, NSAID use, physical function and presence of depression, (see Table). Time to start TNFi after the symptom onset was median 10 (11.5) years at ARI compared to 6 (8) years at OHSU. The baseline BASDAI at the time of initiation of TNFi at ARI was 7 (2.2) compared to 6 (3.9) at OHSU (p=0.04). Adalimumab was the most frequently prescribed TNFi in both places (67% of ARI and 51% of OHSU patients).  Percentage reduction in BASDAI in 1 year from baseline was significantly higher at ARI (64%) as compared to OHSU (17%). According to the NICE guidelines followed in the UK, AS patients are not allowed to switch the TNFi for inefficacy. In OHSU, 22% patients switched TNFi once and 12% switched TNFi more than once, for either allergic reaction or inefficacy. These patients had mean BASDAI score of 3.45 (2.6) and 3.97 (3) respectively after one year.

Conclusion:

Patients at ARI had higher baseline BASDAI and longer time to start TNFi after symptom onset as compared to OHSU.  Higher prevalence of depression in OHSU patients may have affected the change in BASDAI, which is a subjective measure.   OHSU patients who switched TNFi due to inadequate response had a good outcome suggesting that switching TNFi is a valid strategy, which is currently not available to patients in the UK.

	OHSU (2007-2012) N= 41 N, median (iqr) Or N (%)	ARI 2004-2011 N=67 N, median (iqr) Or N (%)	P value
Age years	45 (12)	40.5 (17.5)	0.048*
Female	14 (34.2)	14 (21.9)	0.17
Symptom onset to time of starting TNFi in years	30, 6 (8)	20, 10 (11.5)	0.16
Positive HLA-B27	20 (64.5)	15 (100)	<0.01*
NSAID use	31 (75.6)	64 (100)	<0.01*
Baseline BASDAI	16,  6.0 (3.9)	61, 7.0 (2.2)	0.04*
Baseline RAPID 3	26, 5.2 (2.2)	N/A	N/A
Pain	26,  7 (2.5)	59, 7.4 (2.4)	0.97
Function	26,  2.7 (2.3)	60,  6.2 (3.3)	<0.01*
BASMI	N/A	58,  3.7 (3.2)	N/A
Uveitis	4 (9.8)	11 (17.2)	0.40
Psoriasis	5 (12.2)	5 (7.8)	0.51
Inflammatory bowel disease (IBD)	6 (14.6)	4 (6.4)	0.18
Depression	13 (32.5)%	4 (6.3)	<0.01*
Fibromyalgia	5 (12.2)	N/A	N/A
Ischemic heart disease	2 (4.9)%	1 (1.6)	0.32
% change in BASDAI at 1 year	17.6%	64.7%	<0.01
* statistical significanceN/A “not applicable”

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/comparison-of-tumor-necrosis-factor-inhibitor-use-for-ankylosing-spondylitis-at-university-rheumatology-clinics-in-scotland-and-oregon/