Sonographic Enthesitis and Radiographic Damage in PsA

Table 1. Characteristics of the study population at the time of the assessment ( N = 223)
Variable	Value
Demographics:
Age (years), mean ± SD	56 ± 12.9
Male gender, n (%)	129 (57.9)
PsA duration (years), mean ± SD	16.9 ± 12.4
Psoriasis skin disease duration (years), mean ± SD	28.1 ± 14.5
BMI, mean ± SD	29.8 ± 6.1
Smoking
Current, n (%)	29 (13)
Past, n (%)	70 (31.4)
Clinical activity measures:
Tender joints count, mean ± SD	2.5 ± 5.3
Swollen joint count, mean ± SD	1.1 ± 3.3
Clinical enthesitis, n (%)	31 (13.9)
Dactylitis, n (%)	9 (4)
PASI, mean ± SD	2.6 ± 5.8
Nail lesions, n (%)	59 (26.4)
HLA-B*27	34 (15.5)
Radiographic evaluation:
modified Steinbrocker score
mean ± SD	18.7 ± 33.6
median (25^th, 75^th percentile)	4 (0, 20)
Arthritis mutilans, n (%)	20 (9)
Joint ankylosis, n (%)	26 (11.7)
Periostitis, n (%)	49 (22.2)
mSASSS,
mean ± SD	1.7 ± 7.2
median (25^th, 75^th percentile)	0 (0, 0)
Sacroiliitis, n (%),	82 (37.1)
Sonographic evaluation:
MASEI, mean ± SD	15.7 ± 12.6
Treatment:
DMARDs – current use, n (%)	102 (45.7)
DMARDs – ever use, n (%)	181 (81.2)
Biologics – current use, n (%)	119 (53.4)
Biologics – ever use, n (%)	130 (58.3)

PsA psoriatic arthritis, BMI body mass index, BODPASI psoriasis area and severity index, HLA-B*27 human leukocyte antigen B*27, mSASSS modified Stoke Ankylosing Spondylitis Spine Score, MASEI MAdrid Sonography Enthesitis Index, DMARDs disease-modifying antirheumatic drugs

Table 2. The association between MASEI and modified Steinbroker score - negative binomial regression
Variable*	Univariate regression			Multiple regression**
Variable*	estimate (SE)	exp^(Estimate) (95% CI)	P value	estimate (SE)	exp^(Estimate) (95% CI)	P value
MASEI – total	0.48 (0.11)	1.61 (1.30, 1.99)	<0.001	0.35 (0.10)	1.42 (1.15, 1.73)	<0.001
MASEI – bone score	0.86 (0.19)	2.36 (1.63, 3.38)	<0.001	0.64 (0.18)	1.89 (1.33, 2.69)	<0.001
MASEI – soft tissue score	0.63 (0.20)	1.88 (1.26, 2.77)	0.002	0.37 (0.18)	1.44 (1.03, 2.05)	0.03

MASEI MAdrid Sonography Enthesitis Index
*10 units increase in MASEI
**Each model was adjusted for age, sex, PsA duration, BMI, smoking, current use of DMARDs and biologics

Table 3. The association between MASEI score and features of radiographic damage – Logistic regression analysis
Variable*	Univariate regression		Multiple regression**
Variable*	OR (95% CI)	P value	OR (95% CI)	P value
Joint ankylosis
MASEI total	2.05 (1.52 2.75)	<0.001	1.93 (1.37, 2.72)	<0.001
MASEI – bone score	3.49 (2.09, 5.85)	<0.001	3.24 (1.75, 6.01)	<0.001
MASEI – soft tissue score	2.59 (1.55, 4.31)	<0.001	2.96 (1.36, 4.22)	0.003
Arthritis mutilans
MASEI total	1.96 (1.43, 2.69)	<0.001	1.77 (1.23, 2.54)	0.002
MASEI – bone score	3.94 (2.24, 6.93)	<0.001	3.77 (1.84, 7.70)	<0.001
MASEI – soft tissue score	2.00 (1.15, 3.50)	0.014	1.71 (0.90, 3.26)	0.102
Periostitis
MASEI total	1.48 (1.17, 1.88)	0.001	1.41 (1.08, 1.84)	0.013
MASEI – bone score	2.05 (1.35, 3.11)	<0.001	1.88 (1.17, 3.02)	0.009
MASEI – soft tissue score	1.65 (1.07, 2.53)	0.022	1.52 (0.96, 2.41)	0.07
Sacroiliitis
MASEI total	1.36 (1.10, 1.70)	0.005	1.33 (1.03, 1.72)	0.027
MASEI – bone score	2.12 (1.42, 3.16)	<0.001	2.24 (1.40, 3.61)	<0.001
MASEI – soft tissue score	1.23 (0.84, 1.83)	0.285	1.10 (0.71, 1.70)	0.664

MASEI MAdrid Sonography Enthesitis Index
*10 units increase in MASEI
**Each model was adjusted for age, sex, PsA duration, BMI, smoking, current use of DMARDs and biologics

Table 4. The association between MASEI and mSASSS – negative binomial regression
Variable*	Univariate model			Multivariable model**
Variable*	estimate (SE)	exp^(Estimate) (95% CI)	P value	estimate (SE)	exp^(Estimate) (95% CI)	P value
MASEI – total	0.65 (0.25)	1.92 (1.17, 3.09)	0.009	0.78 (0.32)	2.18 (1.16, 4.09)	0.02
MASEI – bone score	1.23 (0.42)	3.42 (1.52, 7.69)	0.003	1.51 (0.51)	4.52 (1.68, 12.18)	0.003
MASEI – soft tissue score	1.04 (0.50)	2.89 (1.06, 7.61)	0.04	0.70 (0.69)	2.01 (0.52, 7.77)	0.31

MASEI MAdrid Sonography Enthesitis Index
*10 units increase in MASEI
**Each model was adjusted for age, sex, PsA duration, BMI, smoking, current use of DMARDs and Biologics

Authors and Disclosures

Ari Polachek¹, Richard Cook², Vinod Chandran^3,4,5, Dafna D. Gladman⁶ and Lihi Eder^7*

¹Centre for Prognostic Studies in the Rheumatic Diseases, Toronto Western Hospital, University of Toronto, 1–412, 399 Bathurst Street, Toronto, ON M5T 2S8, Canada. ²Department of Statistics and Actuarial Science, University of Waterloo, Waterloo, ON, Canada. ³Department of Medicine and Laboratory Medicine, Institute of Medical Science, University of Toronto, Toronto, ON, Canada. ⁴Department of Pathobiology, Institute of Medical Science, University of Toronto, Toronto, ON, Canada. ⁵Centre for Prognosis Studies in the Rheumatic Diseases, Krembil Research Institute, Toronto Western Hospital, Toronto, ON, Canada. ⁶Center for Prognostic Studies in the Rheumatic Diseases, Toronto Western Hospital, University of Toronto, Toronto, ON, Canada. ⁷Department of Medicine, University of Toronto, Women's College Research Institute, Women's College Hospital, Room 6326, 76 Grenville Street, Toronto, ON M5S 1B2, Canada.

*Correspondence
lihi.eder@wchospital.ca

Authors' contributions
AP contributed to study conception and design, analysis and interpretation of the data and preparation of the manuscript. RC contributed to analysis and interpretation of the data and preparation of the manuscript. VC contributed to study conception and design, analysis and interpretation of the data and preparation of the manuscript. DDG contributed to study conception and design, analysis and interpretation of the data and preparation of the manuscript. LE contributed to study conception and design, analysis and interpretation of the data and preparation of the manuscript. All authors read and approved the final manuscript.

Competing interests
The authors declare that they have no competing interests.

Disclosures
The University of Toronto Psoriatic Arthritis Program is supported by a grant from the Krembil Foundation. Ari Polachek was supported by an educational grant from Janssen Canada. Lihi Eder is supported by a New Investigator Salary Grant from the Arthritis Society and the Canadian Association of Psoriasis Patients. The authors declare that they do not have any potential conflicts of interests