Weight loss and treatment may work together to improve disease symptoms in overweight people with psoriatic arthritis.
A recent study, published in June in Annals of the Rheumatic Diseases, found that patients who took a certain kind of biologic medication while losing weight improved more than patients who just took the medication.
The study involved 138 patients with psoriatic arthritis starting treatment with biologics that target tumor necrosis factor-alpha (TNF-alpha), which is a cytokine, or protein, that promotes inflammation.
People with psoriatic disease who are also overweight may experience a double dose of inflammation, according to the researchers. Previous studies have found that losing weight can reduce psoriasis severity.
As the research team noted in an article published last year in Rheumatology, fat cells secrete many of the same cytokines involved in psoriatic disease, such as TNF-alpha. Even if an overweight patient takes a TNF-alpha blocker, the researchers hypothesized, their body weight may prevent the medication from working.
This study sought to determine whether coupling TNF-alpha treatment with weight loss could improve outcomes for obese patients.
The biologics used in the study were Enbrel (etanercept), Humira (adalimumab) and Remicade (infliximab). All of the participants were overweight or obese, with a body mass index of 25 or more. Half of the patients were placed on a low-calorie diet, restricted to less than 1,500 calories a day, while the other half were simply given nutritional guidelines. Of the original patient group, 126 participants completed the study.
Patients were evaluated once a month, with a final assessment at the end of the six-month study. Researchers employed many different methods of measuring disease improvement, such as the number of swollen or tender joints, the degree of pain the patient experienced and the severity of skin symptoms. These measurements were combined to determine which patients achieved Minimal Disease Activity (MDA), which the researchers defined as a successful treatment outcome.
At the end of the study, almost 43 percent of patients on the diet achieved MDA, along with almost 35 percent of patients in the non-diet group. This number included patients from each biologic group.
The diet had less of an impact on treatment outcome than whether or not the patients lost weight. Researchers found that almost 45 percent of the patients who lost between 5-10 percent of their body weight—and almost 60 percent of the patients who lost more than 10 percent—achieved MDA. This group included both patients who followed the diet and those who did not.
According to the researchers, this suggests that regardless of what a patient eats, losing weight may play a major role in determining treatment outcomes for obese patients who take TNF-alpha blockers.