Relationship between low range body mass index and total knee replacement, the Singapore Chinese Health Study

Abstract

s / Osteoarthritis and Cartilage 22 (2014) S57–S489 S217 2010 to 2075. Albeit the expected costs are mainly driven by female patients, the relative increase in TKA associated costs are greater in men than inwomen due to population shifts. In those aged 80þ, the costs for TKR will increase by 106% and in those aged 90þ by 624%, indicating that perioperative costs in these decades will additionally increase the TKR-associated costs due to co-morbidity, perioperative complications and prolonged postoperative rehabilitation. As the assumptions in this analysis are conservatively taken, the future socio-economic burden to Austrian society might be greater as projected in this study. Fig. 1. Projected numbers of TKR implants in Austria for individuals in their 5th, 6th, 7th, 8th and 9thþ decade with stratification for gender between 2010–2075. Low (ageing), main (most likely) and upper (growth) scenarios are based on population projections of STATISTICS Austria and Austrian prosthesis register. 381 RELATIONSHIP BETWEEN LOW RANGE BODY MASS INDEX AND TOTAL KNEE REPLACEMENT, THE SINGAPORE CHINESE HEALTH STUDY Y.Y. Leung yz, M. Noviani z, J.C. Allen z, L-W. Ang x, R-W. Wang k{, J-M. Yuan k{, W-P. Koh#yy. yDept. of Rheumatology & Immunology, Singapore Gen. Hosp., Singapore, Singapore; zDuke NUS Graduate Med. Sch., Singapore, Singapore, Singapore; x Epidemiology & Disease Control Div., Ministry of Hlth., Singapore, Singapore; kDiv. of Cancer Control and Population Sci., Univ. of Pittsburgh Cancer Inst., Pittsburgh, PA, USA; {Dept. of Epidemiology, Graduate Sch. of Publ. Hlth., Univ. of Pittsburgh, Pittsburgh, PA, USA; Duke NUS Graduate Med. Sch. Singapore, Singapore, Singapore, USA; yy Saw Swee Hock Sch. of Publ. Hlth., Natl. Univ. of Singapore, Singapore, Singapore Purpose: Data on the association between low body mass index (BMI) ranges and risk of knee OA are sparse. We evaluated the association of BMI and total knee replacement (TKR) due to severe knee OA amongst elderly Chinese in Singapore who had low BMI. Methods: We used data from the Singapore Chinese Health Study, a population based prospective cohort of 63,257 Chinese men and women, aged 45 to 74 years old during enrollment in 1993–1998. Detailed information on height, weight, demographic characters, smoking, current diet and lifestyle factors were obtained through inperson interviews. TKR cases indicated for severe knee OA were identified via linkage with nationwide hospital discharge database up to 31 December 2011. We used Cox regression methods to analyze BMI in relation to TKR risk with adjustment for age, gender, education, smoking status, comorbidities and physical activity level. Results: From 52,780 subjects with known BMI data, 1,649 subjects with incident TKR due to severe knee OAwere identified. Themean BMI was 23.1 ( 3.6) kg/m2 and 75% of subjects had BMI <25 kg/m2. There was a strong dose-response relationship between BMI and risk of TKR across all ranges of BMI and both genders after adjusted for other confounding factors. Comparison of the highest BMI decile (median 17.6) with the lowest (median 29.2) showed a significant association with incident TKR [HR 1⁄4 9.86, 95% confident interval (CI) 1⁄4 7.10–13.71]. There was a linear relationship between BMI and risk of TKR (adjusted R-Square 1⁄4 0.973). For each 1 kg/m2 increase in BMI, there was a 12.7% (95% CI of HR 1⁄4 1.1181.136) increased risk of TKR. There was no difference in magnitude of risk with gender. Conclusion: Our findings strongly implicate BMI as a risk factor for TKR indicated for severe knee OA, from low to high BMI ranges in both genders. This supports the link between body weight and biomechanics in causing knee OA. Fig. 1. Fit plot of Ln Relative risk (RR) for knee replacement surgery (TKR) and body mass index for both men and women. 382 THE SUBSTANTIAL PERSONAL BURDEN OF HIP AND KNEE OSTEOARTHRITIS AMONG YOUNGER PEOPLE I.N. Ackerman y, A. Bucknill z, B. Cavka y, R. Page x, P. Schoch x, N. Broughton k, C. Roberts z, C. Brand z. y The Univ. of Melbourne, Melbourne, Australia; zMelbourne Hlth., Melbourne, Australia; xBarwon Hlth., Geelong, Australia; k Peninsula Hlth., Frankston, Australia Purpose: Osteoarthritis (OA) has traditionally been considered a condition of older age. However, younger people are also affected by hip and knee OA, often as a result of sporting, transport and work-related injuries. As studies have generally focused on older individuals, little is known about the experience of younger adults with hip or knee OAwho can face a unique set of pressures including work responsibilities and parenting roles. This study aimed to compare the Health-Related Quality of Life (HRQoL) of younger people with hip or knee OA to ageand sex-matched pop-