Predicting the Long-Term Gains in Health-Related Quality of Life After Total Knee Arthroplasty.
We investigated the predictors of long-term gains in quality-adjusted life years (QALYs) from total knee arthroplasty (TKA) and the patient attributes that predicted cost-effective TKA.



Data on TKA patients (n = 570) from 2006 to 2007 were extracted from a single-institution registry. QALY gains over 7 years post surgery were calculated from health-related quality of life (HrQoL) scores measured preoperatively and annually postoperatively using the short-form health survey (SF-12) instrument. Multivariate linear regression analysis investigated the predictors of QALY gain from TKA from a broad range of preoperative patient characteristics and was used to predict QALY gains for each individual. Patients were grouped into deciles according to their predicted QALY gain, and the cost-effectiveness of each decile was plotted on the cost-effectiveness plane. Patient attribute differences between deciles were decomposed.



After exclusions and dropout, data were available for 488 patients. The average estimated QALY gain over 7 years was 0.77 (95% confidence interval [CI] 0.70-0.83). Predictors significantly associated with smaller QALY gains were comorbidities (Charlson comorbidity index 3+ coefficient -0.54 CI -0.15 to -0.92), the absence of severe osteoarthritis in the ipsilateral knee (-0.51 CI -0.16 to -0.85), preoperative HrQoL (standardized coefficient -0.34 CI -0.26 to -0.43), the requirement for an interpreter (-0.24 CI -0.05 to -0.44), and age (-0.01 CI -0.01 to -0.02). The largest difference between cost-effective and non-cost-effective deciles was relatively high preoperative HrQoL in the non-cost-effective decile.



TKA is likely to be cost-effective for most patients except those with unusually high preoperative HrQoL or a lack of severe osteoarthritis. The poorer outcomes for those requiring an interpreter requires further research.
Centre for Health Policy, School of Population and Global Health, The University of Melbourne, Melbourne, Victoria; Department of Surgery, The University of Melbourne, St Vincent's Hospital, Melbourne, Victoria.
Chris G
CG
Schilling
Department of Surgery, The University of Melbourne, St Vincent's Hospital, Melbourne, Victoria; Department of Orthopaedics, St Vincent's Hospital Melbourne, Melbourne, Victoria.
Michelle M
MM
Dowsey
Centre for Health Policy, School of Population and Global Health, The University of Melbourne, Melbourne, Victoria.
Dennis J
DJ
Petrie
Centre for Health Policy, School of Population and Global Health, The University of Melbourne, Melbourne, Victoria.
Philip M
PM
Clarke
Department of Surgery, The University of Melbourne, St Vincent's Hospital, Melbourne, Victoria; Department of Orthopaedics, St Vincent's Hospital Melbourne, Melbourne, Victoria.
Peter F
PF
Choong
D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001315:Australia; D015897:Comorbidity; D003362:Cost-Benefit Analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010003:Osteoarthritis / Q000601:surgery; D011788:Quality of Life; D019057:Quality-Adjusted Life Years; D012042:Registries; D011795:Surveys and Questionnaires
QALYs; cost-effectiveness; health-related quality of life; prediction; total knee arthroplasty