E-Poster Presentation 30th Australian and New Zealand Bone and Mineral Society Annual Scientific Meeting 2020

Burden of end-stage osteoarthritis in Australia: A population-based study on the incidence of total knee replacement attributable to overweight/obesity (#90)

Lianzhi Chen 1 , Monica Zheng 2 , Ziming Chen 1 , Michelle Lorimer 3 , Christopher Jones 4 5 , Stephen Graves 6 , Peilin Chen 1 , Richard Carey-Smith 7 , Toby Leys 7 , John Papadimitriou 1 8 , Christopher Mitchell 1 , Yi-Gang Huang 9 , David Wood 1 , Max Bulsara 2 , Ming-Hao Zheng 1 10
  1. Centre for Orthopaedic Research, University of Western Australia, Perth, Western Australia, Australia
  2. Institute for Health Research, University of Notre Dame, Fremantle, Western Australia, Australia
  3. South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia
  4. Medical School, Curtin University, Perth, Western Australia, Australia
  5. Department of Orthopaedic Surgery, Fiona Stanley Hospital Group, Perth, Western Australia, Australia
  6. Australian Orthopaedic Association National Joint Replacement Registry , Adelaide, South Australia, Australia
  7. Department of Orthopaedic Surgery, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
  8. Pathwest Laboratories, Perth, Western Australia, Australia
  9. Department of Orthopaedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China
  10. Perron Institute for Neurological and Translational Science, Perth, Western Australia, Australia

Increasing global obesity has been attributable to the increased prevalence of osteoarthritis (OA) but its risk on end-stage OA is still not clear. This population-based study aimed to define population attributable risk of total knee replacement (TKR) associated with obesity in Australia. A total of 191,723 TKRs for primary OA from 2015-2018 and estimated populations with BMI distribution were collected from the Australian Orthopaedic Association National Joint Registry and Australia Bureau of Statistics, respectively. Age- and gender-specific incidence rate (IR) and incidence rate ratio (IR) were calculated for each BMI category. We investigated the time-trend change in incidence of TKR in each BMI category and assessed the influence of obesity on the incidence of TKR in different age and gender groups. Population attributable fraction (PAF) was calculated to infer the effect of obesity on TKR incidence. In total, the number of TKR for primary OA increased 28.33% from 40954 cases in 2015 to 52555 cases in 2018. The greatest increase in number of TKRs performed occurred in individuals with BMI greater than 40.00. Obesity has resulted in the greatest risk of TKR at young population (aged 18-54). There are 3.722-, 13.704- and 18.463-times higher risk in patients with overweight, obesity class I & II and obesity class III than patients with normal weight, respectively. A greater risk of TKR was observed in the female population in obesity class III, at approximately 1.7-time higher than male population. The PAFs of TKR associated with obesity were 34.98% in 2015 and increased by 2% in 2018, with 12156 cases of TKR being attributable to obesity in 2018. In conclusion, obesity contributed to the largest proportion of TKR in young (less than 54) and female patients. Weight loss strategies can be implemented in these populations to reduce or delay the need for TKR.