BRIGHTON, ENGLAND – Very obese patients with early rheumatoid arthritis appear to have higher disease activity at presentation, according to recent data presented at the annual meeting of the British Society for Rheumatology.
In a study of 216 individuals with early, clinically diagnosed rheumatoid arthritis (RA), those with a body mass index (BMI) of 35 kg/m2 or higher were more likely than those with lower BMIs to have higher 28-joint count disease activity scores (DAS28), mainly because of higher erythrocyte sedimentation rates (ESRs).
Photo credit: ©geronimo/Fotolia.com
Photo credit: ©geronimo/Fotolia.comEarly rheumatoid arthritis patients who are very obese appear to present with higher 28-joint count disease activity scores.
As a result, use of the DAS28 to guide clinical decision-making could result in disease-modifying antirheumatic drug (DMARD) therapy being given early on, 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/m2 but less than 35 kg/m2) and just over 11% in the obese II–III category (BMI of more than 35 kg/m2). One-third of patients were overweight and the remaining third were either normal weight or underweight.
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, 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, Ms. Ling 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.