Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Association of BMI and Psoriatic Arthritis Disease Activity.

Eberle2,  Elena, Knight2,  Eric, Raddatz2,  Donald A., Messing5,  Susan, Reed4,  George, Greenberg1,  Jeffrey D., Kremer3,  Joel M.

Millburn, NJ
Bassett Healthcare, Cooperstown, NY
The Center for Rheumatology, Albany, NY
University of Massachusetts, Worchester, MA
University of Rochester, Rochester, NY

Background:

Obesity may induce a low-grade chronic inflammatory state. Adipocytes are involved in the recruitment and activation of macrophages, which produce TNF-alpha, IL-6, and IL-12. Studies have also shown an association between body mass index (BMI) and gouty arthritis and osteoarthritis of the hand joints. Psoriatic arthritis (PsA) patients have a significantly higher mean BMI and prevalence of obesity compared to population-based means. Therefore, we hypothesized that there may be an association between BMI and PsA disease activity.

Methods:

We selected patients with PsA from the CORRONA database for a cross-sectional study. BMI was presented as a categorical and continuous variable. Patients were categorized into quartiles by weight including "Normal Weight" (BMI>=18.5, <25), "Overweight" (BMI>=25, <30), "Obese" (BMI>=30, <40), and "Morbidly Obese" (BMI>=40). Our primary outcomes were 28 tender joint count (TJC) and 28 swollen joint count (SJC). The secondary outcomes were physician global assessment of disease activity (PGDA), physician global assessment of skin involvement (PGSI), mHAQ, ESR, and CRP. We used Poisson regression models to investigate associations as relative risks between BMI categories and tender and swollen joint counts. Generalized estimating equations, employing a robust sandwich estimator for the variance of the beta weights, were used to assess the associations expressed as beta weights for secondary outcomes of interest.

Results:

1980 patients with PsA were identified from the CORRONA registry. 781 participants had ESR values and 593 individuals had CRP values. The majority of the patients had between 1 and 5 tender joints (80%) and between 1 and 5 swollen joints (82%). ESR in the obese quartile was 6 mm/h higher than the normal weight quartile and almost 10 mm/h higher in the morbidly obese quartile.

Conclusion:

BMI>=30 was strongly associated with a higher disease activity in patients with PsA. This association may be the result of the induction of inflammation by adipose tissue as we found a positive relationship between ESR and obesity. There is presently limited recognition of this relationship amongst clinicians. Expanded investigations of the biologic factors associated with obesity and disease activity are needed in patients with Psoriatic arthritis.

Table 1. Association between weight quartiles and tender joint count (TJC) and swollen joint count (SJC). Data are presented as relative risk (RR) per 1 joint increase with 95% confidence interval (CI). Normal Weight quartile (n = 344) serves as the reference group.

Primary OutcomesOverweight (n = 636)Obese (n = 702)Morbidly Obese (n = 298)
TJC1.00 (CI 0.81–1.24)1.35 (CI 1.10–1.65)1.53 (CI 1.22–1.93)
SJC1.01 (CI 0.82–1.26)1.30 (CI 1.06–1.60)1.59 (CI 1.26–2.00)

Table 2. Association between weight quartiles and physician global assessment of disease activity (PGDA), physician global assessment of skin involvement (PGSI), mHAQ, ESR, and CRP. Normal Weight quartile (n = 344) serves as the reference group.*

Secondary OutcomesOverweight (n = 636)Obese (n = 702)Morbidly Obese (n = 298)
PGDA2.1339 (SE 1.2690) p = 0.094.2249 (SE 1.2570) p = 0.00085.9451 (SE 1.5377) p = 0.0001
PGSI0.1544 (SE 0.0632) p = 0.01470.3077 (SE 0.0638) p < 0.00010.3103 (SE 0.0778) p < 0.0001
mHAQ0.0218 (SE 0.0235) p = 0.350.1230 (SE 0.0244) p < 0.00010.2020 (SE 0.0327) p < 0.0001
ESR0.2730 (SE 1.6003) p = 0.866.0946 (SE 1.7701) p = 0.00069.6867 (SE 2.1573) p < 0.0001
CRP0.8044 (SE 1.0156) p = 0.420.7853 (SE 0.7853) p = 0.392.1585 (SE 1.5958) p = 0.17
*The beta weight expresses the rate of change in the outcome for the column BMI quartile vs. the Normal Weight quartile.

To cite this abstract, please use the following information:
Eberle, Elena, Knight, Eric, Raddatz, Donald A., Messing, Susan, Reed, George, Greenberg, Jeffrey D., et al; Association of BMI and Psoriatic Arthritis Disease Activity. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :515
DOI: 10.1002/art.28284

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