BERLIN – Obese patients with psoriatic arthritis demonstrate a worse response when starting anti–tumor necrosis factor therapy than do normal weight patients, but achievement of minimal disease activity can be improved by weight loss, based on two studies by Dr. Giovanni Di Minno, lead investigator on both.
The first study investigated the influence of obesity and the second, the influence of weight loss on response to starting anti–tumor necrosis factor (TNF) therapy.
The study on the effect of obesity on response to anti-TNF therapy in psoriatic arthritis (PsA) involved 135 psoriatic arthritis patients with a body mass index (BMI) over 30 kg/m2and 135 normal weight controls. Dr. Di Minno and his coinvestigators found that the two groups did not differ significantly in terms of disease activity and vascular risk factors including swollen and tender joint counts, levels of C-reactive protein, erythrocyte sedimentation rates, and psoriasis area severity index scores. They found that patients with a BMI over 30 had a higher prevalence of hypercholesterolemia and hypertriglyceridemia.
"Controlling weight is very important for these patients in the long term."
Dr. Di Minno and his associates in the department of clinical and experimental medicine, Federico II University, Naples, Italy, found that at 12 months’ follow-up, 98 of the 270 patients (36.3%) had achieved minimal disease activity (MDA). The prevalence of obesity was higher in those not achieving MDA than in those achieving it (64% vs. 25.5%, P less than .001).
"A BMI of over 30 was shown to be a strong predictor [of not achieving MDA] with a hazard ratio of 4.90 (95%CI: 3.04-7.87; P less than .001)," according to Cox regression analysis findings, reported Dr. Di Minno.
At 24 months, 17.3% of those who achieved MDA a year earlier relapsed, and 82.7% maintained their MDA. "A BMI greater than 30 was associated with a higher risk of disease relapse, with a hazard ratio of 2.04 [95% CI: 1.02-3.61; P = .014]," he said at the annual European Congress of Rheumatology.
Dr. Di Minno also noted that there was no difference found between the three anti-TNF blockers (infliximab, etanercept, and adalimumab) used in the study.
Session moderator Dr. Laura Coates said that the study was valuable because patients with PsA were prone to being overweight, and there was an established link between excess weight, metabolic syndrome, and psoriasis. "Until this study, there were no data to support the concept that weight loss could alter people’s outcome in terms of their arthritis response.
"This provides evidence of an immediate improvement to people’s health with weight loss, in terms of a better response to the anti-TNF therapies," said Dr. Coates of the division of rheumatic and musculoskeletal disease at Chapel Allerton Hospital in Leeds, England.
Furthermore, Dr. Coates noted that there was also a known association between psoriasis/PsA and cardiovascular morbidity related to the metabolic syndrome. "Controlling weight is very important for these patients in the long term as well," she said.
Introducing his second study, which investigated the effect of weight loss in obese patients, Dr Di Minno noted that prior studies had shown that restricting calorie intake reduced obesity-related inflammation.
The study specifically investigated the impact of changes in body weight on the achievement of MDA in PsA patients starting treatment on anti-TNF therapy.
A total of 126 obese (BMI greater than 30) patients with active PsA, who had not responded to traditional disease-modifying antirheumaic drugs were randomized to either a diet of 1,300 calories per day (n = 63), or an unrestricted diet (n = 63), with the advice to eat more vegetables, fish, and fresh fruits and no more than 2 tablespoons of olive oil per day. All patients were encouraged to exercise five times a week, and all started on anti-TNF therapy immediately.
"The intervention diet was the traditional Mediterranean diet rich in fibers, with a careful balance of sugar, proteins, and lipids, similar to the diet used by diabetics," explained Dr. Di Minno. The Mediterranean diet has been shown to lessen inflammation because it is rich in mono- and polyunsaturated fatty acids, antioxidants, dietary fiber, and phytochemicals.
At the 6-month follow-up, the researchers found a 5%-10% weight loss was achieved by 47.6% of patients on the hypocaloric diet versus 28.6% on the unrestricted diet. Only 41.3% of patients on the hypocaloric diet lost more than 10% of their body weight.
Furthermore, patients on the hypocaloric diet had more significant reductions in triglycerides and cholesterol compared with those on the unrestricted diet (29.1% vs. 10% for triglycerides. and 23.7% vs. 8.1% for cholesterol, for hypocaloric and unrestricted diets, respectively).