Overweight patients with RA exhibit less joint space narrowing progression
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Patients with rheumatoid arthritis, particularly older women, who are overweight demonstrate less joint space narrowing progression, independent of smoking status, according to data published in Arthritis Research & Therapy.
“In patients with rheumatoid arthritis (RA), detection of early joint damage by radiography is prognostic and has been previously shown to identify patients more prone to further damage progression,” Emil Rydell, MD, of Lund University, in Malmö, Sweden, and colleagues wrote. “There are conflicting data on the impact of patient age and sex, while for cigarette smoking and body constitution there is mounting evidence suggesting important associations with radiographic progression.”
“RA-related joint damage includes erosions and cartilage destruction, with the latter causing joint space narrowing (JSN),” they added. “Despite that separate scores of these are included in the commonly used radiographic scoring methods, most previous studies have evaluated only combined total scores of the radiographic damage. Whether the development and progression of erosions and JSN represent separate underlying mechanisms in the process of destructive arthritis in RA is unclear.”
To determine how patient characteristics, smoking status, disease activity, anthropometrics and body composition impact erosion and joint space narrowing progression among those with early RA, Rydell and colleagues studied an inception cohort of 233 consecutive patients at the rheumatology outpatient clinic of Skåne University Hospital Malmö, as well as from four private-practice rheumatologists in the area. Recruitment was completed from 1995 to 2005.
Trained readers scored radiographs of patients’ hands and feet according to the modified Sharp-van der Heijde score. Meanwhile, fat mass and lean mass distribution were measured at baseline via dual energy X-ray absorptiometry. The researchers then examined potential predictors of erosion and joint space narrowing progression from enrollment to 5-year follow-up. In all, radiographs at baseline and 5years were available for 162 participants.
According to the researchers, the median, interquartile progression of erosion and joint space narrowing scores were 4 and 8, respectively. Rheumatoid factor was a significant predictor of both erosion and joint space narrowing score progression and, in adjusted analyses, anti-CCP antibodies predicted erosions while the erythrocyte sedimentation rate was predictive of both. Smoking and high baseline disease activity — defined as a DAS28of more than5.1 — predicted erosion progression.
Baseline erosion score was associated with progression of both erosion and joint space narrowing progression. Meanwhile, the baseline joint space narrowing score predicted the progression of joint space narrowing only.
Being overweight or obese — defined as a BMI of at least 25kg/m2 — was a significant negative predictor of joint space narrowing score progression (=–0.14; P=0.018, adjusted for rheumatoid factor, age and baseline joint space narrowing score). This was also the case when additionally adjusting for current or past smoking (P=.041). Among women, this effect was observed in those of estimated post-menopausal age — older than51years — but not in younger women. In addition, the truncal to peripheral fat ratio was associated with less joint space narrowing score progression in women, but not in men.
“Overweight RA patients had less JSN progression, independent of smoking status,” Rydell and colleagues wrote. “This effect was seen in particular among older women (mainly post-menopausal), but not younger. Truncal fat was associated with less JSN progression in female patients. Smoking predicted erosion progression, and erosions may precede JSN. BMI and fat distribution may influence cartilage damage in early RA and might be related to hormonal factors.”
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