BRIGHTON, ENGLAND – Very obese patients with early rheumatoid arthritis appear to have higher disease activity at presentation, according to recent data.
In a study of 216 individuals with early, clinically diagnosed rheumatoid arthritis (RA), those with a body mass index (BMI) of 35 kg/m
As a result, by using the DAS28 to guide their clinical decision making, physicians may give disease-modifying antirheumatic drug (DMARD) therapy too early in the course of the disease, suggested Stephanie Ling, who presented the findings.
Ms. Ling, a fifth-year medical student at the University of Liverpool, England, noted that earlier, more aggressive treatment of obese RA patients might explain why some studies have suggested that obesity, somewhat paradoxically, is actually beneficial in some patients with RA.
Indeed, studies have linked obesity with reduced mortality (Arch. Intern. Med. 2005; 165:1624–9; Ann. Rheum. Dis. 2010;69:i61–4) and protection against radiographic joint damage (Ann. Rheum. Dis. 2008;67:769–74), although high levels of adiponectin – secreted from the fat tissue – are associated with increased joint inflammation (Arthritis Rheum. 2009;61:1248–56).
“Physiologically, obesity is characterized by the expansion of white adipose tissue, which is not a benign tissue,” Ms. Ling explained.
White adipose tissue secretes fatty acids, and its constituent cells, the adipocytes, also secrete proinflammatory proteins, or adipokines.
“Obesity can be thought of as a chronic inflammatory state,” said Ms. Ling, adding that studies also indicate that “obesity could have adverse effect on RA disease activity.”
In the current study, patients' baseline disease characteristics, including DAS28 scores, rheumatoid factor status, and anti-cyclic citrullinated protein antibody status, were assessed according to BMI at presentation. All patients had early RA diagnosed by a consultant rheumatologist and had symptoms lasting for less than 1 year. The mean age of participants was 57 years and 57% of the cohort was female.
Patients were grouped according to their BMI category, as defined by World Health Organization (WHO) criteria. One-third fulfilled criteria for obesity, with approximately 22% in the obese I category (BMI more than 30 kg/m
Results showed that obese II–III patients were more likely to present with elevated (5.1 or higher) DAS28 scores than their lighter counterparts. Odds ratios (OR) adjusted for age, gender, and smoking status were 4.1 for DAS28 and 3.67 for ESR when comparing the very obese patients with the other BMI groups.
Considering each component of the DAS28 separately, Ms. Ling said, a high ESR (32 mm/h or more) was the main factor that appeared to be significantly higher as body weight increased. There was no association with tender or swollen joint counts, global visual analog scale, symptom duration, or rheumatoid factor/anti-cyclic citrullinated protein antibody status, she said.
“There is a need for well-designed longitudinal studies to examine the effect of obesity on the extent of RA disease progression,” she suggested.
Ms. Ling reported no conflicts of interest.
Because obesity increases the ESR, overweight RA patients may have a higher DAS28 score than their disease merits.
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