The Effect of n-3 Polyunsaturated Fatty Acids on Risk Markers for Cardiovascular Disease and Inflammation in Patients With Psoriatic Arthritis

Method Study design: The study was designed as a randomized, double-blind, placebo-controlled, multicenter trial. The patients were randomly assigned in blocks of five by a computer-generated block sequence. For 24 weeks patients were assigned to daily intake of 6 capsules containing either 3 g of n-3 PUFA (50% EPA and 50% DHA) from fish oil capsules or 3 g of olive oil (approximately 80% of oleic acid and 20% linoleic acid). All the investigators, patients and research staff were blinded to the supplementation codes. Patients were asked to maintain their usual diet during the whole study. The study was conducted in accordance with the Declaration of Helsinki and Good clinical practice (GCP).

Subjects: Patients with PsA defined by Classification criteria for psoriatic arthritis (CASPAR) (25) were enrolled from the Departments of Rheumatology, Aalborg University Hospital and Department of Rheumatology, Vendsyssel Hospital, in Denmark. The inclusion criteria were PsA in adult above 18 years of age with any disease activity while exclusion criteria were documented cardiac arrhythmias, treatment with biological drugs or treatment with oral corticosteroids.

Compliance was assessed by counting capsules during the last visit. Patients were defined as non-compliant if >150 capsules were returned and those were not included in the per-protocol analysis.

All participants gave their written informed consent and the regional ethics committee of Northern Region Denmark, approved the study.

Clinical assessment: Patients were assessed at baseline, after 12 weeks of supplement and after 24 weeks. At baseline, duration of disease, medical history, smoking habits and diet were obtained Medical history of diabetes mellitus, hypertension and dyslipidemia were assessed and was defined as present if the patient received dietary or medical therapy for the condition. A food questionnaire was used to assess patients' fish consumption at lunch and dinner. A score for fish intake was given according to the following: never eat fish = 1; eat fish once a month =2; eat fish two to three times a month = 3; eat fish once a week = 4; eat fish two to three times a week = 5; and eat fish at least once daily = 6.