Fish oil in knee osteoarthritis: a randomised clinical trial of low dose versus high dose.
OBJECTIVE
To determine whether high-dose fish oil is superior to low-dose supplementation for symptomatic and structural outcomes in knee osteoarthritis (OA).


METHODS
A randomised, double-blind, multicentre trial enrolled 202 patients with knee OA and regular knee pain. They were randomised 1:1 to high-dose fish oil (4.5 g omega-3 fatty acids) 15 mL/day or (2) low-dose fish oil (blend of fish oil and sunola oil; ratio of 1:9, 0.45 g omega-3 fatty acids) 15 mL/day. The primary endpoints were Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain score at 3, 6, 12 and 24 months, and change in cartilage volume at 24 months. Secondary outcomes included WOMAC function, quality of life, analgesic and non-steroidal anti-inflammatory drug use and bone marrow lesion score.


RESULTS
Although there was improvement in both groups, the low-dose fish oil group had greater improvement in WOMAC pain and function scores at 2 years compared with the high-dose group, whereas between-group differences at 1 year did not reach statistical significance. There was no difference between the two groups in cartilage volume loss at 2 years. For other secondary endpoints, there was no difference between the two groups at 2 years.


CONCLUSIONS
In people with symptomatic knee OA, there was no additional benefit of a high-dose fish oil compared with low-dose fish oil. The combination comparator oil appeared to have better efficacy in reducing pain at 2 years, suggesting that this requires further investigation.


BACKGROUND
Australian New Zealand Clinical Trials Registry (ACTRN 12607000415404).
Rheumatology Unit, The Queen Elizabeth Hospital, Woodville, South Australia University of Adelaide, The Health Observatory, Adelaide, South Australia.
Catherine L
CL
Hill
Royal North Shore Hospital, Institute of Bone and Joint Research, St Leonards, New South Wales, Australia.
Lynette M
LM
March
Menzies Research Institute, Hobart, Tasmania, Australia.
Dawn
D
Aitken
Rheumatology Unit, The Queen Elizabeth Hospital, Woodville, South Australia.
Susan E
SE
Lester
Rheumatology Unit, The Queen Elizabeth Hospital, Woodville, South Australia.
Ruth
R
Battersby
Menzies Research Institute, Hobart, Tasmania, Australia.
Kristen
K
Hynes
Royal North Shore Hospital, Institute of Bone and Joint Research, St Leonards, New South Wales, Australia.
Tanya
T
Fedorova
Rheumatology Unit, Royal Adelaide Hospital, Adelaide, South Australia.
Susanna M
SM
Proudman
Rheumatology Unit, Royal Adelaide Hospital, Adelaide, South Australia.
Michael
M
James
Rheumatology Unit, Royal Adelaide Hospital, Adelaide, South Australia.
Leslie G
LG
Cleland
Menzies Research Institute, Hobart, Tasmania, Australia.
Graeme
G
Jones
D000082:Acetaminophen / Q000627:therapeutic use; D000368:Aged; D000700:Analgesics / Q000627:therapeutic use; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D018771:Arthralgia / Q000188:drug therapy*; D002358:Cartilage, Articular / Q000473:pathology*; D019587:Dietary Supplements; D004311:Double-Blind Method; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D059352:Musculoskeletal Pain / Q000188:drug therapy*; D009929:Organ Size; D020370:Osteoarthritis, Knee / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D010147:Pain Measurement; D011788:Quality of Life
D000700:Analgesics; D000894:Anti-Inflammatory Agents, Non-Steroidal; D015525:Fatty Acids, Omega-3; D000082:Acetaminophen
Epidemiology; Knee Osteoarthritis; Treatment