Marine n-3 Polyunsaturated Fatty Acids in Psoriatic Arthritis – Inflammation and Cardiac Autonomic and Hemodynamic Function

This thesis is based on three studies of patients with established psoriatic arthritis (PsA) aiming at investigating the effect of marine n-3 polyunsaturated fatty acids (PUFA) on clinical symptoms and selected measures of inflammation, cardiac autonomic and hemodynamic function in these patients.

Study I aimed to investigate whether training in standardised assessment of enthesitis in PsA is able to improve interobserver variation. Furthermore, ultrasonography (US) and clinical assessment of enthesitis were compared in detecting abnormalities. The results of this study showed significant reduction in interobserver variation with training in standardised enthesitis scoring systems, suggesting training sessions of clinicians before assessment of enthesitis in daily practice. US revealed more advanced stages of enthesitis, such as enthesophytes and erosions, which were not detected by clinical examination.

To investigate effects of marine n-3 PUFA on clinical outcomes, important biochemical markers and cardiovascular risk in patients with PsA a randomized placebo-controlled trial was undertaken (Study II and III). One-hundred and forty-five patients were enrolled and randomized to a supplement with either 3 g of marine n-3 PUFA (6 capsules of fish oil) or 3 g of olive oil daily for 24 weeks. A total of 133 patients (92%) completed the study. The difference in the outcomes between baseline and 24 weeks was analysed within and between the two supplemented groups.
In Study II, the effects of n-3 PUFA supplementation on outcome measures for disease activity, NSAID and paracetamol consumption and inflammation quantified as leukotriene formation from stimulated granulocytes was examined. The n-3 PUFA supplemented group showed improvement in outcome measures for disease activity, though without reaching a significant difference between the groups. However, use of NSAID and paracetamol was significantly reduced from baseline to week 24 in the n-3 PUFA group; also when compared with the control group. Furthermore, there was a significant decrease in leukotriene B4 (LTB4) formation from activated granulocytes in the n-3 PUFA group compared with controls. The results indicate a beneficial effect of n-3 PUFA on joint inflammation and pain.
In Study III, the aim was to investigate the effect of marine n-3 PUFA on cardiac autonomic function assessed by heart rate variability (HRV), blood pressure (BP), pulse wave velocity (PWV) and central BP. After 24 weeks of supplementation, there was a trend towards increase in HRV in the intention to treat analysis and a significant increase in HRV in the compliant patients. This finding may suggest a protective effect of n-3 PUFA against cardiovascular disease in this population. There were, however, no changes in BP, PWV or central BP between supplements.