Background/Purpose:
Adipose
tissue and adipokines are linked to inflammation. The relationship of obesity
to rheumatologic disease activity is complex and recent studies demonstrate a connection
(1-3). Our objective was to assess association of disease activity with obesity
in rheumatoid arthritis (RA), ankylosing spondylitis (AS) and psoriatic
arthritis (PsA) in a single center biological registry.

Methods:
Hacettepe University Rheumatology Biological database is a single center
registry, including 1015 RA, 814 AS and 203 PsA patients on biologics. Collected
data include demographics, 28 tender/swollen joint counts, 100mm visual analog
scale (VAS) for patient global assessment (PtGA), fatigue, pain, ESR, CRP,
health assessment questionnaire (HAQ), Bath Ankylosing Spondylitis Disease
Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI),
PsAID-12 and DAS-28.  BMI was recorded before anti-TNF treatments. BMI≥30
was defined as obesity. We used the following cut-offs to dichotomize groups:  DAS28>3.2,
BASDAI>4, BASFI>4, PSAID>4, HAQ>0.5, SJC≥1, TJC≥1, for PtGA/BASDAI/BASFI/Fatigue/Pain>40
mm, ESR and CRP>ULN.

Results:
There were 655 RA (79.1%F), 624 AS (33.5% F) and 161 PsA (65.8%F), patients. Mean(SD)
age was 52.8 (12.5) 41.8 (11.4) and 44.8 (11.8) years. Mean(SD) disease
duration was 11.5 (8.0), 10.1(7.5) and 10.3(7.3) years. In RA, AS and PsA mean(SD)
 BMI was 29.1 (5.9), 27.2 (5.4), 28.7 (6.1); and %BMI>30 were 40.2, 24.5 and
37.3.  Disease activity groups by BMI categories are shown in Table.

Conclusion:
In
these cross sectional view, obese RA (DAS-28, all PROs, acute phase reactants)
and PsA (BASDAI, PsAID, pain) patients had more active state, however obesity
did not influence on activity of AS patients. Functional impairment of obese
patients may be related mechanical effect of weight rather than disease
activity. For each disease, different influence of BMI on disease activities
need to assess at other biological registries.   

References:

1.   
Sandberg
ME et al. Ann Rheum Dis. 2014;73:2029-33.

2.   
Durcan
L et al. J Rheumatol. 2012;39:2310-4.

3.   
Eder
L et al. Ann Rheum Dis. 2015;74:813-7.

Table. Disease activity and
patient reported measures by BMI categories