title: Patients with knee osteoarthritis undergoing total knee arthroplasty have a lower risk of subsequent severe cardiovascular events: propensity score and instrumental variable analysis.
abstract: OBJECTIVE
  This population-based study investigated the subsequent cardiovascular risk of patients with knee osteoarthritis underwent total knee arthroplasty in Taiwan.
  
  
  METHODS
  This was a population-based follow-up study of 22931 patients diagnosed with knee osteoarthritis between 2008 and 2011. Each patient was followed for 3 years or until death. Treatment was dichotomized into conservative treatment and TKA. The association between TKA and cardiovascular disease (CVD) events was analyzed using propensity score analysis and instrumental variable analysis and two-stage least-squares regression model.
  
  
  RESULTS
  Patients with knee osteoarthritis who underwent TKA had a lower 3-year cumulative risk of stroke and acute myocardial infarction (AMI). After adjusting for measured risk and confounding factors, propensity score showed a 0.56 fold (adjusted OR = 0.56; 95% CI, 0.51-0.61; p<0.001) risk for CVD in those with TKA. Use of instrumental variable analysis for adjusting measured and unmeasured factors and two-stage least squares regression model revealed that the average treatment effect of TKA was statistically associated with a decreased 7% risk of CVD events (95% CI, 0.2%-13.6%).
  
  
  CONCLUSIONS
  Our study revealed that patients with knee osteoarthritis who underwent TKA had a lower risk of suffering from a future severe cardiovascular event. This benefit may be attributed to an improvement in physical activity, reduction of psychosocial stress, and/or a decreased use of NSAIDs as a result of having undergone TKA.
authors.affiliation: Department of Orthopedics, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan.
authors.forename: Wen-Yan
authors.initials: WY
authors.lastname: Lin
authors.affiliation: Department of Otolaryngology, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan; Department of Education, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan; School of Medicine, Tzu Chi University, Hualian, Taiwan; Center for Clinical Epidemiology and Biostatistics, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan.
authors.forename: Ching-Chih
authors.initials: CC
authors.lastname: Lee
authors.affiliation: Department of Medical Research, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chia-Yi, Taiwan.
authors.forename: Chia-Wen
authors.initials: CW
authors.lastname: Hsu
authors.affiliation: School of Medicine, Tzu Chi University, Hualian, Taiwan; Division of Allergy, Immunology, and Rheumatology, Department of Internal Medicine, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan; Department of Life Science and Institute of Molecular Biology, National Chung Cheung University, Chiayi, Taiwan.
authors.forename: Kuang-Yung
authors.initials: KY
authors.lastname: Huang
authors.affiliation: Department of Education, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan; School of Medicine, Tzu Chi University, Hualian, Taiwan; Joint Center, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan.
authors.forename: Shaw-Ruey
authors.initials: SR
authors.lastname: Lyu
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods; D002318:Cardiovascular Diseases / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D020370:Osteoarthritis, Knee / Q000601:surgery*; D057216:Propensity Score; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology