Fatty acid intake and polyunsaturated fatty acid biomarkers and risk of total knee or hip arthroplasty among older women in the Women's Health Initiative.

OBJECTIVE: The objective was to determine whether baseline fatty acid intake and erythrocyte omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) can predict risk for total hip arthroplasty (THA) and total knee arthroplasty (TKA) in older women.

METHODS: This was a prospective analysis of 34,990 women in the Women's Health Initiative (WHI). Dietary fatty acids were estimated from food frequency questionnaires. Imputed erythrocyte PUFAs were available in a sub-cohort of 3428 women. Arthroplasty (THA and TKA), used as a surrogate of severe osteoarthritis, was identified via linked Medicare data. Cox proportional hazards models were constructed to estimate risk of arthroplasty.

RESULTS: Risk of THA was associated with higher intake of arachidonic acid, [multivariable hazard ratio (HR) quartile (Q)4 vs Q1: 1.16; 95% CI: 1.01, 1.34; p for linear trend = 0.03] and higher intake of eicosapentaenoic acid + docosahexaenoic acid [(EPA+DHA), HR Q4 vs Q1: 1.20; 95% CI:1.05, 1.39; p for linear trend=0.003]. There was a linear trend (p=0.04) for higher risk of THA with higher erythrocyte EPA+DHA in BMI-adjusted models; however, there was no significant difference in THA by quartiles of erythrocyte EPA+DHA (p=0.10). Dietary fatty acids and erythrocyte PUFAs were not significantly associated with risk of TKA.

CONCLUSIONS: Higher baseline intakes of arachidonic acid and EPA+DHA were associated with a modestly higher risk of THA. No association was found between fatty acids and TKA. Further research in populations with direct measures of osteoarthritis severity is needed to better understand the importance of PUFAs in modulating osteoarthritis and arthroplasty risk.