Association between dairy product consumption and incidence of total hip arthroplasty for osteoarthritis

Objective. The aim of this prospective cohort study was to determine whether dairy product consumption was associated with the incidence of total hip arthroplasty for osteoarthritis (OA). Methods. There were 38,924 participants from the Melbourne Collaborative Cohort Study who had dairy product consumption recorded in 1990-1994. The incidence of total hip arthroplasty for OA during 2001-2013 was determined by linking cohort records to the Australian Orthopaedic Association National Joint Replacement Registry. Results. Over an average of 11.8 years of followup, 1505 total hip arthroplasties for OA were identified (524 in men, 981 in women). In men, a 1 SD increase in dairy product consumption was associated with a 21% increased incidence of total hip arthroplasty for OA (HR 1.21, 95% CI 1.10-1.33), with a dose-response relationship observed for quartiles of dairy product consumption (p for trend = 0.001). These results were independent of age, body mass index, country of birth, education, smoking status, vigorous physical activity, calcium supplementation, energy consumption, circulating 25-hydroxy vitamin D, hypertension, and diabetes. No significant association was observed for women (HR 1.02, 95% CI 0.95-1.09). Conclusion. Increasing dairy product consumption was associated with an increased risk of total hip arthroplasty for men with OA, with no significant association observed for women. Understanding the mechanisms may help identify strategies to prevent hip OA, particularly for men.