Obesity negatively predicts minimal disease activity achievement in patients with PSA

According to a study presented today at EULAR 2012, the Annual Congress of the European League Against Rheumatism, patients with psoriatic arthritis (PsA) who are starting anti-tumour necrosis factor (anti-TNF) treatment and adhere to a hypocaloric diet have a significantly greater chance of achieving minimal disease activity (MDA, an important measure of disease activity) at six months compared to those on a standard diet.

The results of an Italian study of 138 obese PsA patients demonstrated that those who achieved a ≥10% weight loss following a calorie restricted diet, were more likely to achieve MDA, compared to patients on a standard diet (p=0.001). These patients also had significantly higher changes in erythrocyte sedimentation rate (ESR, a test that indirectly measures the amount of inflammation in the body), and c-reactive protein (CRP, a marker of systemic inflammation, a recently identified predictor of structural damage progression) compared to patients on a standard diet.

"A study presented at the 2009 meeting of the Society for Investigative Dermatology, alerted us to the fact that patients with psoriatic arthritis have an increased prevalence of obesity, however our study has gone beyond that, assessing whether diet is able to improve the achievement of minimal disease activity in obese patients treated with anti-TNFs" said Dr. Dario Di Minno from the University of Naples Federico II, Italy and lead author of the study. "The results of our study suggest that obese patients with psoriatic arthritis who stick to a hypocaloric diet have a greater chance of achieving treatment goals."

The study demonstrated that a hypocaloric diet is a predictor of MDA achievement (hazard ratio [HR]: 4.79; p=0.002) after six months of treatment with anti-TNFs in patients as compared to those on a standard diet. Of the 138 obese subjects with PsA, 69 received a hypocaloric diet and 69 a self-managed diet. At baseline and at six months follow-up, patients underwent a complete clinical rheumatologic and laboratory evaluation.

In a separate PsA study by the same authors, 135 obese and 135 matched normal-weighted patients (controls) with active disease starting treatment with anti-TNFs were followed for 24 months to evaluate whether the presence of obesity impacts the achievement of MDA. Of the 270 subjects, 36.3% achieved MDA and the prevalence of obesity was higher in those not achieving MDA than in those achieving it (64.0% versus 25.5%, p<0.001). After adjusting for all the other variables, obesity was associated with a higher risk of not achieving MDA (HR: 4.90, 95%, CI: 3.04-7.87, p<0.001). Among the 98 subjects that had achieved MDA at the 12 month follow-up, the presence of obesity was associated with a poor probability of maintaining MDA at 24 month follow-up (HR:2.04, 95% CI:1.015-3.61, p=0.014).