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21-07-2011 | Immunology | Article

Obesity increases SLE burden of disability


Free abstract

MedWire News: Tackling obesity may be key to managing disability in women with systemic lupus erythematosus (SLE), suggests research published in the journal Arthritis Care and Research.

The study showed that obesity was significantly associated with poorer physical function and greater disability in SLE both cross-sectionally and prospectively, even among patients with a body mass index (BMI) that was lower than the usual clinical marker for obesity.

Patricia Katz (University of California, San Francisco) and co-workers examined BMI information for 716 women with SLE who were interviewed twice with a 4-year interval regarding physical function and disability. In particular, the patients were assessed using employment status, the Short Form (SF)-36 Physical Function (PF) subscale and the Valued Life Activities (VLA) Disability questionnaire.

Using a BMI of 30 kg/m2 or higher, 27.8% of the women were defined as obese, rising to 40.6% when the BMI cutoff was lowered to 26.8 kg/m2 or above.

Regardless of which BMI obesity definition was applied, obese woman had significantly poorer function at baseline than those with a healthy BMI, with a deficit of 20-33% found depending on which BMI cutoff and functional assessment was applied.

Specifically, at baseline women with a BMI of 26.8 kg/m2 or above had a significant 4.3 point deficit on the SF-36 PF and a VLA difficulty of 0.09 points higher than non-obese patients, after adjusting for demographic factors, glucocorticoid use, SLE activity and duration, and depression and other comorbidities. For women with a BMI of 30.0 kg/m2 or above, the changes were 4.2 points and 0.08 points, respectively.

Patients with an elevated BMI were also more likely to be unemployed than non-obese women but this did not reach statistical significance.

Further, 4 years later, women who were obese had experienced greater functional decline than their non-obese counterparts.

Compared with non-obese patients, those with a BMI of 26.8 or 30.0 kg/m2 or above had a significant 6% and 4% greater increase in SF-35 PF scores, denoting greater disability, and were a significant 40% and 50% less likely to be employed, respectively. There was a significant 13% increase in VLA score for women with a BMI of 30 kg/m2 or above compared with non-obese patients. However, the 5% increase of VLA in women with a BMI of 26.8 kg/m2 was not significant.

Noting that the negative impact of obesity occurred at a lower BMI than usually considered problematic clinically or in the general population, Katz et al suggest that using the lower BMI cut-off point for obesity could help identity women at increased risk for poor outcome and disability.

"Because of the high rates of disability in SLE, identifying preventable risk factors, such as overweight and obesity, has the potential to decrease the negative impact of the disease on functioning," they comment.

MedWire ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Lynda Williams

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